Bot. J. Linn. SOC., 71: 67-88. With 8 figures
September 1975
The distribution of Australian relict plants and
its bearing on angiosperm evolution
R. MELVILLE
The Herbarium, Royal Botanic Gardens, Kew
Accepted for publication April I975
The distribution of relict plants in the Australian flora shows a bimodal distribution of genera
with relict vegetative characters and a unimodal distribution centred on N.E. Queensland for
floral characters. Archaic features of the vegetative group link them with the Glossopteridae ot
Permian age. The geophysical history of the continent is reviewed and indicates only minor
climatic changes since the Permian, which would permit the survival of primitive vegetative
features. The bimodal distribution of this group is accounted for by the Cretaceous marine
invasion of the continent and the unimodal distribution of the floral relicts by a preponderance
of genera of Indo-Malaysian affinity, which could not have entered Australia until contact was
made with New Guinea about 45 m.y. B.P. Two different cycles of evolutionary diversification
are responsible for the two elements. Vegetative features of the Proreaceae relate to the
Glossopteridae and are supported by Permian fossils scarcely distinguishable from modern
leaves of Epacridaceae. If recent discoveries of Glossopteris fructifications are accepted as
pro-angiosperms, it is shown that some anomalies in the vascular supply to the androecium in
the Proteaceae can be accounted for.
CONTENTS
Introduction
. . . . . . . . . . . .
Distribution patterns of relicts . . . . . .
. . . . .
Geophysical history of Australia
Origin of relict plants
. . . . . . . .
Relict Epacridaceae
. . . . . . . . . .
Leaf evolution in Proteaceae
. . . . . .
Evolution of the androecium in Proreaceae
. .
Evolution of the gynoecium in Proreaceae
. .
Proto-Proteaceae defined
. . . . . . .
Discussion
. . . . . . . . . . . .
Acknowledgement
.
References
. . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .
67
68
72
74
75
77
82
84
84
85
87
87
INTRODUCTION
In his last paper, the eminent palaeobotanist H. Hamshaw Thomas (1961),
after discussing various lines of evidence concerning the evolution of the
flowering plants, drew attention to the “need to scrutinize the whole of our
Angiosperm morphology” and he continued with the words “for much of it is
based merely on traditional teaching and not on objective evidence”. At that
time I had already some evidence from floral anatomy that the Glossopteridae
6
67
68
R. MELVILLE
might be the group from which the Angiosperms had evolved, and I was
embarking on a worldwide survey of leaf architecture t o determine whether
any evidence had survived in the leaves of living angiosperms that could support
such an origin. The search was rewarded by the discovery in a number of
families of evidence for the evolution of foliage leaves from the three principal
form genera of the Glossopteridae, Gangamopteris, Glossopteris and
Taeniopteris, which existed together in the Permian. Some of the preliminary
observations in this field have already been published (Melville, 1969, 1971).
The highest concentrations of plants exhibiting these features occur in
Australia and South Africa. As with relict species in general, many of the
species involved are rare, and the desirability of ensuring their survival by
suitable conservation measures to enable full scientific studies to be made was
urged at the 12th Pacific Science Congress (Melville, 1973). The matter was
then discussed at meetings of the Terrestrial Conservation section of the
International Biological Programme at Canberra, the outcome of which was the
addition of a chapter on ‘Primitive seed plants in the Australian flora’ to the
report of the Committee (Specht, Roe & Boughton, 1974).
DISTRIBUTION PATTERNS OF RELICTS
The sector in the above report relating to relict plants retaining primitive
vegetative features was based on my own recent studies, whilst that concerned
with floral characters was prepared by a team of Australian botanists. The
distributions of the two groups of plants were mapped separately and they
show some striking discrepancies in distribution pattern. The concentration of
plants with primitive floral characters is highest in the Cape York Peninsula and
it decreases gradually in passing southwards along the Dividing Range into
Victoria. The plants having primitive vegetative characters have two areas of high
concentration, one in southern Queensland and central New South Wales and
the other in the south-western province of Western Australia. The two
distribution types appeared not to be closely related and the discrepancies to
be worthy of closer investigation. The published figures were not strictly
comparable, for the floral group referred to genera and included gymnosperms,
whereas the vegetative group contained only Angiosperms and the figures were
for species. It appears that a comparison made at generic level would be most
appropriate, especially as species that were more advanced on account of
reduction were omitted from the lists for some of the genera. The figures for
the two groups of plants have therefore been recalculated on a generic basis and
the comparison confined to angiosperms (Table 1).
The general distributional picture was not altered by this operation. The
highest concentration of genera with primitive floral characters remains in N .E.
Queensland (with 76) and the number declines gradually around the eastern
seaboard down to 1 5 in E. Victoria and 16 in Tasmania (Fig. 1). The bimodal
distribution of plants with primitive vegetative characters in the east and the
south-west of the continent was again evident (Table 1). The maximum number
of genera (20) occurs in the Stirling province, with 18 and 17 respectively in
the adjacent Darling and Eyre provinces of the south-west. The nearest
approach to these figures in the east is in S.E. Queensland and the central
AUSTRALIAN RELICT PLANTS
69
Table 1. Regional distribution of Australian relict genera of Angiosperms
Province
(after Specht
e t a l . , 1974)
Vegetative characters
Epacridaceae
Others
Province
(after Burbidge,
1960)
Floral Characters
All taxa
western Australia
Eyre
Stirling
Warren
Avo n
Darling
Irwin
Coolgardie
Austin
Ashburton
Carnegie
Fortescue
Dampier
Fitzroy
Ord
Hann
8
9
5
4
7
4
4
1
-
-
9
South West
13
11
9
12
11
8
7
4
3
2
1
South Eremean
North Eremean
North
3
6
4
6
N e w South Wales
Far W. Plains
Western Plains
North W. Slopes
Central W. Slopes
South W. Slopes
N. Tablelands
N. Coast
Central Tablelands
Central Coast
S. Tablelands
S. Coast
-
1
1
3
-
1
-
3
8
9
12
-
11
8
8
5
2
3
3
3
Western Plains
4
Central
5
North East
39
North Coast
36
Eastern
25
North East
North
East
West
South West
South Central
South East
76
14
43
2
2
2
43
Eastern
North East
15
10
Southern
11
4
Queensland
North East
North
East
West
South West
South Central
South East
Victoria
E. Coast Plains
E. Highlands
W. Highlands
W. Coast Plains
Wilson’s Prom.
Little Desert
Mallee
1
1
5
-
5
3
3
1
-
-
10
6
8
10
8
-
-
3
10
7
6
1
3
2
3
5
3
Western
North West
7
5
12
5
3
Main Island
16
-
Temperate
9
Tasmania
Main Island
Bass Strait Islands
South Australia
South East
Murray
South
Kangaroo Island
Yorke Peninsula
Flinders
Eyre
8
6
7
8
3
2
5
4
2
4
4
2
3
R . MELVILLE
70
Table l-cont.
Province
(after Specht
e t a l . , 1974)
South A ustralia-con t.
Nullarbor
North East
Far North East
Far North West
Northern Territory
Northern
Semi-arid
Arid
Vegetative characters
Epacridaceae
Others
Province
(after Burbidge,
1960)
Floral Characters
All taxa
1
1
I
1
Eremean
5
-
6
1
Tropical
Eremean
19
3
-
3
-
-
coastal province of N.S.W., both with 16 genera. North-east Queensland and
other parts of northern Australia have only 6 of these genera.
The Epacridaceae, mapped separately in Fig. 2, were the main contributor t o
these totals, the highest numbers of genera 9 and 8 occurring in the adjacent
provinces Stirling and Eyre in the South West and 11 and 12 in the Central
South Coast and Central Tablelands regions of New South Wales. The
Proteaceae came next in point of numbers, with the highest concentration
confined to the damper south-west corner of Western Australia, the number of
genera for the separate provinces being Irwin 4, Avon 6, Darling 5, Warren 5 ,
Stirling 7 and Eyre 5. Elsewhere the number of genera drops to 1 or 2, with 3
in the Central Tablelands area of New South Wales. The bimodal distribution in
the Proteaceae is scarcely discernible.
From a preliminary comparison of the two groups it appeared that the
vegetative group contained a large proportion of genera that were confined to
or which had their main diversification in Australia. The floral group, although
it contained many endemic genera, also included a number of families with a
wide extra-Australian distribution. I t therefore appeared worthwhile to enquire
further into the relationships of the two groups.
Taking first the floral primitives of the Annonaceae, there are three
monotypic genera in Queensland and representatives of nine other genera with
wide distributions in south-east Asia and Malaysia, some of them extending to
Africa. The situation in the Menispermaceae is much the same, with five
monotypic genera in Queensland and N.S.W., three genera ranging from Africa
to Malaya and five others with a general distribution beyond the bounds of
Australia in Indo-Malaya and New Guinea. All the genera of Lauraceae listed
have a wide distribution outside of Australia in south-east Asia and beyond.
The genera of Cunoniaceae and Monimiaceae, each with five endemic in
Australia, otherwise have their relationships in the south Pacific and New
Guinea. These five families account for 57 genera which may have invaded
the continent from the north or have evolved from invaders that have not
survived. To this group we can add the representatives of the Ceratophyllaceae,
Aristolochiaceae, Hamamelidaceae, Hernandiaceae, Myristicaceae, Nymphaeaceae, Phytolaccaceae, Piperaceae, Ranunculaceae, Alismaceae and Pandanaceae. This accounts for 81 genera of the floral primitives or 74% of the total.
AUSTRALIAN RELICT PLANTS
71
Figure 1 . Distribution in Australia of relict Angiosperm genera based on florai characters.
Numerals give number of genera in each province.
The largest contributors t o the remainder are the Gyrostemonaceae and the
Proteaceae. The Gyrostemonaceae, with five genera, is endemic to Australia but
closely related to the widespread Phytolaccaceae. The Proteaceae is a special
case, for it is well represented in both groups with 1 1 genera classified as relicts
on floral characters and 8 on vegetative characters. All the genera in the floral
group have only one or two species each, except for Persoonia, which is the
only genus also included in the vegetative group. Six genera confined t o
northeast Queensland are rain forest trees with simple pinnate leaves of the
brochidodromous type. With these characters and their relatively unspecialized
flowers, they come very close to Johnson & Briggs’ (1963, 1975) concept of
their proto-Proteaceae. These authors believe that the Proteaceae originated
under rain forest conditions, a point of view which fits in with the existence of
the other families of rain forest affinity included among the floral group of
relicts. For this to be true, rain forest ecosystems must have had a very long
period of existence in Australia. By contrast, the members of the vegetative
group of relicts are predominantly xeromorphic and for the greater part belong
t o ecosystems of arid or semi-arid conditions.
72
R . MELVILLE
Figure 2 . Distribution in Australia of relict genera of Epacridaceae based on vegetative
characters. Numerals give number of genera in each province.
GEOPHYSICAL HISTORY OF AUSTRALIA
The differing ecological requirements of the two groups of relict plants
appear to conflict and prompted a search €or any evidence that might reconcile
the discrepancy. It is generally accepted that a long period of time was required
for the evolution of the Angiosperms, and several authors (White, 1963;
Hamshaw Thomas, 1958; Alexrod, 1952; Croizat, 1966) have put back the
period of their origin to the Permian. I t is appropriate accordingly to enquire
into the geophysical history of the Australian continent and the climatic and
physical changes brought about by continental drift.
Palaeobotanical and geological evidence indicates that in the Permian
Australia was part of the great southern continent of Gondwanaland, and a
large part of its southern- half was subjected to the Permo-Carboniferous
glaciation in common with parts of South America, Africa, India and
Antarctica. The climate of the continent during the Permian must have varied
over different parts of its surface from temperate to periglacial or glacial. When
the continent of Gondwanaland is reconstructed for Permo-Carboniferous time
AUSTRALIAN RELICT PLANTS
73
using palaeomagnetic data, the south poles for South America, Africa, India and
Australia are closely clustered (Creer, 1970). In the Triassic the poles for South
America, Africa and India remain closely clustered, but that for Australia has
moved away a5out 20", indicating that drift had occurred in the interval.
Unfortunately no palaeomagnetic data for the Triassic of Antarctica are
available, but evidence from sea-floor spreading indicates that Australia began
to separate from Antarctica about 50 million years (m.y) ago, early in the
Eocene (Weissel & Hayes, 1971). It is reasonable to assume, therefore, that
Australia and Antarctica drifted in unison in the Triassic. There may then have
been a pause until the eastward drift of Australia was resumed in the Jurassic
(Creer, 1970). As a result of deep-sea drilling, the age of the sea floor off the
Exmouth Plateau to the west of Australia indicates that the resumption of
movement began about 140 m.y. ago. (Heirtzler et al., 1973; McElhinny, 1973)
and continued into the Cretaceous at least to 100 m.y. ago.
During the period from the Triassic, through the Jurassic and Cretaceous
until northward drift began in the Eocene, Australia was situated about 15"
south of its present latitude (Jones, 1971). Climatic changes over this period of
about 150 m.y. must have been minimal and would have given little stimulus to
change in the vegetative organs of plants already adapted to the ambient
conditions. Such relatively stable conditions would have been conducive to the
survival of primitive structures. The separation of Australia from Antarctica,
starting about 50 m.y. ago, was well under way by the late Eocene, as dating of
the ocean floor has demonstrated (Jones, 1971; McElhinny, 1973), and it was
not until this period that any severe climatic stress was imposed upon the flora.
Australia drifted north for about 1487 km according to Weissel & Hayes
(1971). If the movement was at the rate of 10 cm per annum, the journey
would have taken abour 15 m.y. and contact should have been made with the
island arcs to the north of the continent towards the end of the Oligocene,
about 35-30m.y. ago. The Miocene folding of the island arcs, which was
presumably a consequence of the collision between the two tectonic plates, fits
in very well with this chronology.
The break up of the Gondwana continent was episodal. In the first episode
Australia and Antarctica were separated from South America, Africa & India in
the Triassic. After a pause the second episode began in the Jurassic with the
northward drift of India (Creer, 1970) and the resumption of the eastward drift
of Australia. The third episode was the separation of Africa and South America
in the Cretaceous (Creer, 1970; Larson & Ladd, 1973; Reyment, 1969). After
another pause, the fourth episode was the northward drift of Australia starting
in the Eocene. The interpretation of these episodes is closely linked with the
reconstruction of the Gondwana continent. A critical factor in these
reconstructions is the position^ of Madagascar, which materially effects the
positions of India and Australia. Two sites have been proposed, one at the
mouth of the Zambesi and the other off the coast of Kenya. Du Toit (1937)
chose the northern site, being influenced by a lack of evidence for Karroo beds
on Madagascar at the time he wrote (Wellington, 1955). This was unfortunate,
as the missing evidence has since been found (Bessairie, 1946), but in the
interval most authors have followed Du Toit's lead. Additional evidence for the
southern position of Madagascar has recently been published (Tarling, 1972:
King, 1973) and, on the whole, the scatter of palaeomagnetic poles is reduced
74
R. MELVILLE
in the resulting reconstruction. In accepting the southern position for
Madagascar it is necessary to reject most of the reconstructions of Gondwanaland thzt have figured in recent biological literature (e.g. Smit!i, Briden &
Drewry, 1973; Smith & Hallam, 1970).
Returning now to Australia, the evidence indicates that the continent was
separated from Africa and India by a considerable marine gap in the first
episode of drift and was distant from any other tropical land mass from the
Triassic until late in the Oligocene, when contact was made with the northern
island arcs through New Guinea. Thus it was not until about 35-30 m.y. ago
that a path opened for the southward migration into Queensland of those
genera and families with affinities in S.E. Asia, Malaysia and India, which
constitute such a large proportion of the floral relicts of Queensland (Table 1,
Fig. 1). The extent to which they could spread would depend upon the
existence of suitable conditions for the development of rain forest. Did such
conditions exist?
The lack of suitable rain forest habitats would have slowed down the
invasion from the north of the Malaysian element in the Australian flora. It also
has a bearing on the evolution of purely Australian elements, for Johnson &
Briggs (1975) regard the rain forest genera of northern Queensland, Cardwellia,
Darlingia, Hollandea, Musgravea and Placospermum, as the most primitive
members of the Proteaceae. Based to some extent on these genera, their
ancestral “Proto-Proteaceae” are evergreen rain forest trees with simple
pinnate-reticulate leaves of the brochidodromous* type, flowers with a perianth
of a single whorl of four members, and stamens with two traces. The basic
chromosome number n = 7 is also regarded as primitive and probably rightly so,
but of the genera mentioned, only the monotypic Placospermum has this
number. The evidence in favour of a rain-forest origin of the Proteaceae seems
to be extremely slender. Against this must be placed the fact that the basic
chromosome number n = 7 is found only in the PersooBieae, to which
Placospermum belongs, but which also contains Persoonia, which in the wide
sense embraces over 70 species, of which only one-P. toru A. Cunn. of New
Zealand-is a tetraploid. Persoonia also has many species with leaves that on
other grounds are relatively primitive and can be linked with the fossil record.
This point is considered further below.
ORIGIN OF RELICT PLANTS
On the basis of the geophysical evidence, subtropical to warm temperate rain
forest must have developed relatively late in the history of Australia. The bulk
(74%) of the present rain forest relicts appear to be adventive from the north.
Among the remaining floral relicts the Gyrostemonaceae, Emblingiaceae and
Proteaceae appear to be ancient autochthonous survivals. Contrast this with the
vegetative groups of relicts, of which all appear to be autochthonous, with
perhaps the ‘exception of Euphrasia, which may have arrived by an antarctic
route during the Tertiary. Consistently with its adventive origin, the floral
group has a unimodal distribution declining southwards along the Dividing
Range. The vegetative group has a bimodal distribution with the nodes centred
A term introduced by von Ettingshausen (1861) for pinnate leaves with a well developed
inframarginal vein formed by looping together of the principal lateral veins.
AUSTRALIAN RELICT PLANTS
75
in the south west and in south Queensland and central New South Wales. This
bimodal distribution is probably the result of the marine invasion, which
occurred in the late Cretaceous and extended into the Eocene, almost cutting
the continent into two islands (Andrews, 1916). After the regression of the sea,
dry conditions in the centre may have prevented the restoration of the uniform
distribution which had existed previously over the continent.
The other remarkable feature of the vegetative group is the retention of
features, in but slightly modified form, which were characteristic of the flora of
the Permian or earlier. How could this possibly happen? The answer must lie in
the geophysical history of the continent. Plants that had become fully adapted
in their vegetative organs to a temperate climate remained under similar
climatic conditions, with only minor fluctuations, from the Permian, through
the period of the eastward drift of the continent until northward drift began
about 55 m.y. ago. The northward drift was then about equal to the breadth of
the continent. Plants in the south of the continent would have to adapt to the
increasing warmth of the climate or die out if unable to do so. Plants of the
north, however, were able to migrate southwards by their normal dispersal
mechanisms, thereby keeping pace with the climatic change and remaining in
their accustomed zone. Under these conditions the mutation pressure for
readaptation to the ambient conditions would be at a minimum and there need
be little change in the vegetative organs. Such conditions must have been of
rare occurrence in the history of the planet, at least during the Phanerozoic
period. Only one other region, southern Africa, was subjected to comparable
conditions by continental drift. Africa began to drift t o the north early in the
Triassic (Creer, 1964, 1970) and, as in Australia, plants were able to migrate to
the south in unison with the drift movement. The result has been the survival
of numerous species in the Cape flora, which have retained similar archaic
characters to those of southern Western Australia. This applies especially to the
Proteaceae.
RELICT EPACRIDACEAE
Among the vegetative relicts, some of the most primitive leaves occur in the
Epacridaceae, where entire flabellate leaves with an open dichotomous venation
lacking any anastomoses are found in some species of Epacris and in
Coleanthera (Fig. 3). This type of simple leaf is known first in the southern
hemisphere from the Devonian of South Africa, where it is represented by
Platyphyllum albanense (Plumstead, 1967). Later, in the Carboniferous, larger
leaves were developed with a more elaborate venation system, but still without
anastomoses. These are regarded by Plumstead ( 1 969) as proto-Glossopteridae
and they lead on in the Upper Carboniferous to primitive forms of
Gangamopteris with vein anastomoses of the simplest types. In Australia, fossil
leaves very closely resembling leaves of the Epacridaceue in size and general
aspect have been reported by Walkom from the Permian of New South Wales
(Walkom, 1921, 1928). Some of these leaves appear to be without
anastomoses, but in others a few simple cross connections link some of the
parallel veins (Fig. 3A). Walkom also illustrates two leafy shoot tips (Walkom,
1928: t. 36, figs 1, 2) which indicate a habit very similar to that of modem
epacrids. These leaves were evidently a puzzle to him, and he suggested that
they might be scale leaves of a Glossopteris as they were associated in the same
76
R. MELVILLE
Figure 3. A. Fossil leaf published originally (Walkom, 1928: t . 36, fig. 4) as a “scale leaf” of
Glossopteris. B . Leaf of Astroloma rectum R . B . C . Leaf o f Coleanthera myrtoides Stschegl. B
& C show complete venation systems.
deposit with Glossopteris leaves. For this to be true, one would expect some
evidence of a transition between the so-called scale leaves and the normal
foliage of Glossopteris. There does not appear to be any. On the other hand, by
courtesy of Dr E. P. Plumstead, I have examined the extensive collection of
‘scale leaves’ in the Bernard Price Institute in Johannesburg and found nothing
comparable with Walkom’s fossils. Scale leaves in the African collections could
be arranged in graded sequences to form a leaf spectrum with normal leaves of
either Gangamopteris or Glossopteris. Other Australian scale leaves could also
be fitted in but not those of Walkom’s shoots, which show only slight
variations in leaf shape similar to those observed in the shoots of living epacrids
and illustrated in ar, earlier paper (Melville, 1952). An attempt to match the
fossil leaves in other Angiosperm families met with little success. The closest in
appearance were Aspalathus cordata (L.) Dahlgr. and A . angustifolia (Lam.)
Dahlgr., South African members of the Leguminosae, but the match was much
poorer. However, it would be unwise on the present evidence to claim
Walkom’s fossils as Epacridaceae or proto-Epacridaceae. The leaf is of such a
primitive and simple type that it may have been an evolutionary stage in several
families. However, the possibility of a relationship should be borne in mind
since the fossils occur in an area where the highest concentration of extant
genera of Epacridaceae is also to be found. Whatever their true affinity, it is
evident that relatively small heath-like leaves had evolved by the mid-Permian.
AUSTRALIAN KELICT PI*ANTS
77
LEAF EVOLUTION IN PROTEACEAE
Another family in which many primitive leaf types have survived is the
Proteaceae. The venation pattern of the large inflorescence bracts of the Waratah
(Telopea speciosissima R.Br.) is scarcely altered from that of a typical early
Permian Gangamopteris (Fig. 4). The differences are due t o a failure of some of
the minor veins to link up with their neighbours in Telopea, so that areolae are
Figure 4. Inflorescence bract of Telopea speciosissima R.Br. showing gangamopteroid venation
parrern. A. Complete bract. €3. Portion enlarged, all veins shown.
78
R. MELVILLE
not completed and some of the veins are free-ended. Similar bracts occur in
Knightia deplanchei Vieill. and K. strobilina (Lab.) R.Br., and other genera
show stages in the reduction in size and complexity of the venation system.
No foliage leaves have survived in the Proteaceae with venation patterns as
primitive as that of the Telopea bract, but there are many in which the median
vein has been strengthened to form a midrib, often accompanied by two
stronger laterals, as in Adenanthos venosa Meissn. (Fig. 5 ) . Here, also, the
gangamopteroid areolae are incomplete though many features of the glossopterid syndrome remain (Melville, 1969). The absence of a marginal vein is
another feature of A . venosa, though the process of formation of a marginal
vein by the looping together of vein endings can be studied in A . ellipticu
George and in other Australian Proteaceae. I t is a repetition of a process which
was developed in the Permian and recorded in the leaves of Glossopteris
angustifolia (Feistmantel, 1881 ; Melville, 1969). Marginal veins have also been
observed by the writer in G. angustifolia and in at least one other Glossopteris
species, collected at Estcourt in Natal.
Stages in the transformation of the Adenanthos venosa type of leaf into
more definitely pinnate types can be followed in Persoonia. In a species such as
P. elliptica R.Br. (Fig. 6 ) many of the veins in the proximal half of the leaf are
Figure 5 . Perrophile rrifida R.Br. A . Leaf with a few minor veins omitted. B. Apical lobes with
complete venation system. C. Apex redrawn with lobes fused and veins of equal strength to
show similarities to Gangarnopteris, dotted lines complete areolae. D. Adenanthos venosa
Meissn. A11 veins shown. A gangamopteroid pattern with three veins enlarged and partial
breakdown of areolae.
AUSTRALIAN RELICT PLANTS
79
Figure 6. Persoonia elliptica R. Br. A. Complete leaf, smaller veins omitted. B. Leaf base.
C. Leaf apex. All veins shown in B & C.
flabellately parallel, but parts of some have been strengthened and have linked
up with oblique veins, also strengthened, and so have made connection with the
median vein (midrib). In the distal half, the pinnate pattern is more evident but
longitudinal veins can still be seen, sometimes crossing the stronger pinnate
veins and sometimes interrupted. There is a complete or almost complete
marginal vein and in addition a submarginal or inframarginal vein formed of a
series of loops connecting the distal ends of the pinnate veins. The loops appear
to have been formed by differential strengthening and modification of suitably
placed arms of minor bifurcations (Figs 6 and 7N). The result is a pattern
approaching the brochidodromous type, but with erratically spaced lateral
pinnate veins. The true brochidodromous type, which Johnson & Briggs (1975)
regard as primitive in the Proteaceae, is a later development. It is probably
brought about by the operation of a diffusion reaction early in the ontogeny of
80
R. MELVILLE
the leaf, which is responsible for the regular spacing of the lateral costae
(Melville, 197 l ) , coupled with a regularization of the interconnecting loops.
Later stages in the evolution of the brochidodromous leaf can be seen in the
genus Stenocarpus. The leaves of S. salignus R.Br. are at a stage between that of
Adenanthos venusa and Persoonia elliptica R.Br., with three or sometimes five
or more strengthened longitudinal veins, and they feature many characters of
the glossopterid syndrome. Some acutely pointed major areolae foreshadow the
development of the brochidodromous arch, which becomes fully developed in
S. reticulatus C. T. White. At the same time S. reticulatus has changed over to a
rather coarse angular reticulum, while still showing some features transitional
to S. salignus. S. sinuatus Endl. presents the most advanced stage in this genus,
with a brochidodromous pinnate leaf having the coarse reticulum almost
effaced and replaced by a fine, regular pentagonal to hexagonal mesh. The
appearance of this fine hexagonal reticulum may be due to the development of
another type of diffusion reaction at a rather late stage in the ontogeny of the
leaf (Melville, 1971), which marks the ultimate point of this line of evolution.
The physical forces responsible for the development of this hexagonal
venation pattern may operate at any point in an evolutionary sequence. In the
genera Ban ksia and Dryandra a fine approximately hexagonal reticulum
(Fig. 7L) is characteristic of the majority of species. This has replaced and
almost effaced a very primitive pinnate type of venation that had no
relationship at all to the brochidodromous type. Nor is there evidence for the
derivation of these genera or any other Proteaceae from a Glossopteris type of
leaf in which the midrib was primitively manystranded by the lateral
aggregation of many traces. The primitive Banksiinae probably had elongated
gangamopteroid leaves (Fig. 7F), which gave rise to simple midribs as in
Adenanthos venosa and Persoonia elliptica, along which short dichotomous
lateral veins were arranged. Dentation of the margin then gave rise t o a pattern
like that of Petrophile carduacea Meissn., and the hexagonal pattern was
overlaid on this or on pinnatifid or pinnatisect modifications of it in different
species (Fig. 7K, L). Note here the double-Y arrangement of veins at the base
of the sinus (Fig. 7J) which is the inevitable result of the extension of a sinus
into a dichotomous system. This feature appears repeatedly among the
relatively primitive leaves of the Proteaceae, when the margin is broken by
dentation or sinus formation. The double-Y pattern appears also in Stylidium
barleei under similar conditions.
The development of a fine regular approximately hexagonal reticulum, as in
Banksia and Dryandra, is an example of a process that may supervene at any
stage in the evolutionary sequence. Its effects are manifest in Glossopteris
elongata Dana and in the Proteaceae in the more advanced leaf types.
The dissection of a simple leaf by dentation to pinnatisection to the
compound pinnate condition is another process that may occur at any time in
the evolutionary sequence. The advancement of the venation pattern within the
lobes or leaflets may then continue at various rates in different taxa. The
combination of these processes within the Proteaceae has led to the
development of the widest range of leaf architecture of any Angiosperm family.
It is not proposed to digress further here on this aspect of leaf evolution, but it
is appropriate to give an example of dissection in one of the relict types. The
example chosen. Petrophile trifida R.Br. (Fig. 5 ) , is slightly less advanced in its
AUSTRALIAN RELICT PLANTS
81
K
Figure 7. Leaf evolution in the Proreaceae. A. Dichotomous photosynthetic branch system
(Psilophyte stage). B. Stirlingia spp., Isopogon spp. Isotomously dichotomous leaf with
segments containing fascicles of dichotomous veins. C. Isopogon villosus Meissn. Detail of
venation at a fork. D. Planated dichotomously veined leaf (Plaryphyllum stage). E. Gangamopreris. Dichotomous system with anastomoses b u t no midrib. F. Narrow-leaved
Gangamopreris. Veins aggregating in median line. G. Simple entire leaf with midrib b u t few or
no anastomoses. H. Proto-Banksiu or Proto-Dryandra. As G b u t margin dentate. J . Petrophile
carduacea Meissn. Same stage as H, all veins shown. K. Dryandra nobilis Lindl. Principal veins as
in H but overlaid b y a fine reticulum. L. D. nobilis. Detailed to show obscuring of principal
veins by fine reticulum. M. Adenanrhos elliprica George. Modification of the gangamopteroid
pattern by emphasis of a few veins and partial breakdown of the reticulum. N. Persoonia
elliptica R.Br., showing major veins, single midrib; further breakdown of the gangamopteroid
pattern and formation of irregular inframarginal loops. 0. Detail of formation of a
brochidodromous type of loop. P. Srenocarpus rericulams C. T. White, showing major veins and
brochidodromous loop system more uniformly developed.
general venation pattern than Persoonia elliptica (Fig. 6 ) , and if the lobes were
pressed together to eliminate the sinuses an oblanceolate leaf with a number of
sub-parallel veins would result. The enlargement of the leaf apex (Fig. 5B)
shows the complete venation system. The differential thickening of veins
emphasizes some of the longitudinal veins at the expense of others but does not
completely mask the similarity to the flabellate pattern of a Gangamopteris.
Similarly, differential thickening of oblique veins is evident in the veins
supplying the lobes and the sinuses, while other oblique veins remain
unthickened. Many of the minor veins have failed to link up and form complete
areolae, a feature which is common not only in the Proteaceae but in other
families, such as Cruciferae, Compositae and Umbelliferae, where there is
evidence for the breakdown of an earlier venation pattern in transition to a
later type. If the Petrophile leaf tip is redrawn as an entire structure and equal
emphasis is given to all veins, extending free ends to complete areolae (shown
dotted in Fig. 5C), then the similarity to a Gangamopteris is greatly enhanced.
Evidence of this kind, repeatable in other families, supports the view that the
82
R. MELVILLE
Glossopteridae were the progenitors of the Angiosperms. It is highly improbable that the similarity is fortuitous, especially as leaves with venation patterns
scarcely distinguishable from Glossopteris itself occur in other angiosperm
families, such as Linaceae, Thymeleaceae and Foetidiaceae.
EVOLUTION O F THE ANDROECIUM IN PROTEACEAE
From the foregoing it is evident that there is a considerable body of evidence
suggesting that the ancestors of the Proteaceae may have been Glossopteridae.
On the other hand, the flowers are advanced with gamopetalous corollas and
specialized adaptations for pollination by Hymenoptera and birds, two groups
that did not exist in the Permian, when the Glossopteridae were flourishing. To
resolve this anomaly we must look more closely at the flowers. Haber (1960)
has made an extensive and critical study of floral vascular systems in the
family, which revealed an anomalous situation in the androecium. Each tepal
bears a single stamen, which in some genera has a single vascular trace attached
to the median tepal bundle as in a number of other Angiosperm families. In
other genera, such as Persoonia, Hakea and Telopea, the stamen trace is double
at the base, but unites further up into a single trace which supplies the anther.
Franklandia is unique in having a double trace at the base, which fuses into one
as in Persoonia, and then at about the level of the fusion a third trace departs
from the median tepal trace to join the others and enter the anther as a single
trace. From this evidence it may be deduced that the androecium in the
Proteaceae consisted originally of one, two or three single stamens or of a
similar number of stamen fascicles attached to each tepal. Androecia of these
types are known in other families, but are there any fossils that would fit these
requirements? If credence can be given to the leaf evidence we should look
among glossopterid fructifications for the appropriate structures.
A number of new glossopterid fructifications described from Australia
(Holmes, 1974) and South Africa (Lacey et al., 1974) include male sporophylls
with two, three and possibly more dichotomous trusses of microsporangia.
Others from India, such as Eretmonia utkalensis Surange & Maheshwari
(Surange & Chandra, 1974), have only a single truss. All of these are assigned to
the form genus Eretmonia, in which the sporangial trusses may be attached to
various parts of the sporophyll-petiole, midrib or lateral veins-but are not
axillary. The South African specimens (E. natalensis Du Toit) vary in the
number of sporangial trusses from one specimen to another, and it appears that
the number of trusses was fluctuating, if not in a single species, then certainly
within one genus. Such a situation must have existed in the proto-Proteaceae to
account for the variations in the androecium in modern Proteaceae.
The transformation of an Eretmonia sporophyll into an androecial component of an Angiosperm flower would be a relatively simple process. In the first
stage the microsporangia would become adnate to one another in 2’s or 4’s to
form bithecate or tetrathecate anthers arranged in dichotomous trusses. The
Proteaceae have advanced far beyond this stage, but tepals with several
dichotomous stamina1 trusses survive in Ricinus, while a single truss is found in
Spathiostemon and there are many stages of reduction in other genera of
Euphorbiaceae down to a pair of stamens or a single stamen on one tepal. The
AUSTRALlAN RELICT PLANTS
83
course taken by the Proteuceue was different, and on the evidence of floral
vascular systems (Haber, 1960) the main evolutionary trends were towards
reduction of sporangial or anther number and adnation of stamina1 trusses of
stamens. Starting with three sporangial trusses, genera with simple stamen
traces are readily enough accounted for by reduction to a single median truss
and then to a median stamen attached to the median tepal trace near the base.
The only other change necessary was adnation of the filament to the tepal. The
Persooniu type of stamen could have originated by suppression of the median
stamen truss, leaving the two lateral trusses, followed by adnation of the anthers
into a single group and the reduction of anther number finally to one. During
this process the distal ends of the vascular supply of the two trusses fused into
a single trace and the compound filament became adnate to the tepal. The
situation in Frunklundiu could be an intermediate stage in the evolution of the
N
M
T
Figure 8 . Evolution of the androecium in the Proteaceae. A. Eretmonia utkalensis Surange &
Maheshwari, with one dichotomous microsporangial branch. B. C . Eretomonia naralensis stage,
with two or three dichotomous microsporangial branches. D. E. cooyalensis Holmes, with
microsporangia condensed into heads. E, F, G. Formation of dichotomous stamen trusses by
connation of microsporangia: E. Spathiostemon stage, G . Ricinus stage. H, J, K. Reduction of
stamen trusses to single stamens (H is a common Angiosperm type). L. Adnation of a single
Stamen to a tepal (as in most genera of Proteaceae). M . Fusion of two stamen traces and
adnation of filament t o tepal (as in Persoonia). N. Fusion of three stamen traces and adnation
of filament t o tepal (as in Franklandia). 0. Connation of stamens of three adjacent tepals and
sterilization of outer lateral anther lobes (as in Conospermum and Synaphaea). P. Projected
future evolution of 0 by reduction to one anther on fused stamen traces of three adjacent
tepals.
7
84
R. MELVILLE
Persoonia type, but not a derivative of it as Haber (1960) suggested. The
tendency to reduction and adnation in the androecium still continue in the
family, as exemplified by Synaphaea and Conospermum. In these genera three
tepals form one lip of the flower and their anthers are to some degree adnate.
The central stamen of the three is fully fertile but the outer lobes of the two
lateral stamens are sterile. Projecting the process into the future the final result
could be a single stamen perched on the stamina1 vascular supply of the three
tepals. The repetition of an evolutionary process, as here suggested, is not an
uncommon event, for it is manifested in the Compositae in simple and
compound capitulae and in the Grurnineae in simple and compound spikes and
panicles. The aggregation of microsporangia into clusters is shown in the
Australian Eretmonia cooyalensis Holmes (Holmes, 1974), which provides
some evidence for the early establishment of the trend towards aggregation
(Fig. 8D).
EVOLUTION OF THE GYNOECIUM IN PROTEACEAE
On account of the extreme reduction of the gynoecium in the Proteaceae, its
origin is less clear and its interpretation is bound up with the nature of the
nectary scales. Haber (1960) considers the nectaries to represent a second
corolline whorl alternating with the tepals. I t is difficult not to accept this
point of view for Franklandia, where these organs form an inner lining for the
tepaline tube with vestiges of a vascular system at the base. Usually the
nectaries are free and alternate with the sepals, as might be expected if the
perianth had originally consisted of two free fertile whorls. The four inner
bundles at the base of the flower, which Haber calls “carpellary” bundles,
probably were originally common traces to the petal + ovary complex. In order
to account for existing structures, the original petal-ovary complex must have
consisted of a leaf-like blade corresponding with a petal on which was borne a
smaller scale on which in turn was borne a dichotomous branch bearing
terminal ovules. The relationship of the ovuliferous branch and scale would be
similar t o that of Austroglossa walkomii Holmes (Holmes, 1974), but the whole
petal-ovary complex would be more akin to a Plzima sp. (Plumstead, 1958).
The follicle would be formed by folding of the scale around the fertile branch.
Reduction and sterilization of three of the four complexes must have followed,
leaving one complete follicle complex and three petals. The different
orientations of the ovary now observed within the family may depend upon
which member remained fertile. Finally, the single follicle in the course of its
ontogeny took over the whole of the residual meristem of the flower, with the
result that the ventral traces became attached to whichever floral traces
happened to be nearest during their development. Similar processes have
occurred in the Winteraceae (Tucker & Gifford, 1964) and the Leguminosae
(Newman, 1936; Moore, 1936) in establishing the apparently terminal position
of the ovary.
PROTO-PROTEACEAE DEFINED
From this examination of the evidence it is now possible to suggest what was
the general appearance of the pro-angiosperm ancestors of the Proteaceae. They
AUSTRALIAN RELICT PLANTS
85
were probably shrubs or small trees living in a temperate climate, bearing leaves
of the Gangamopteris type. Their reproductive structures terminated the
branch tips and were probably on short lateral branches. The reproductive unit
consisted of four free scales of the Eretmonia type, each having one to three
dichotomous trusses of microsporangia, followed by four gynoecial units also
free from one another. The gynoecial unit consisted of a gangamopteroid blade
probably with the venation pattern already somewhat reduced and giving rise
to a smaller scale bearing a dichotomous truss of ovules. This concept is based
upon the fossil record and on the vascular anatomy of the flowers, but it is very
different from that of Johnson &? Briggs (1975). Their proto-Proteaceae are
already Angiosperms and their supposedly primitive pinnately veined brochidodromous leaf is much more advanced than many other leaf types in the
family. The direction in which evolutionary sequences of leaf types within the
family must be read is settled unequivocally by the fossil record and indicates
the brochidodromous type as one of moderate advancement.
The claim of the Proteaceae to primitive or relict status rests primarily on leaf
and other vegetative characters which date back to the Permian. These features
are survivals from an early cycle of diversification belonging to the preAngiosperm glossopterid stage of evolution. The flowers are advanced by
reduction along the lines discussed above and by sympetally and adnation of
parts. These floral specializations belong to a later cycle of evolutionary
diversification appertaining to the Angiosperms alone and dating back to the
Cretaceous. They represent the re-adaptation of the reproductive structures for
pollination by Hymenoptera, Lepidoptera and birds, animal phyla that were
also expanding and diversifying in the Cretaceous. Similarly, the flowers of the
Epacridaceae are adapted for specialized pollinators, whereas the leaves of some
genera are scarcely distinguishable from Permian fossils. Surely these are relicts
more remarkable than the Echidna or Ornithorrhynchus, for they originated at
a much ea.rlier period.
DISCUSSION
When considering the evolution of the Australian flora it is impossible to
ignore the geophysical history of the continent. In this context the Proteaceae
are a test case. The archaic vegetative features observed in Australia are
repeated again in South Africa, but in the latter continent they are confined
mainly to the Proteoideae, while in Australia they are shared between the
Proteoideae and Grevilleoideae. Considerable parallel evolution must have
occurred in the two continents. A time limit is set by the nature of these
archaic features, for they link up with the Glossopteridae of Permian age and
palaeomagnetic evidence (Creer, 1964, 1970) indicates that Africa with South
America and India separated from the remainder of Gondwanaland early in the
Triassic. The great diversity of genera, within the two continents, with its
differing emphasis at subfamily level, is consistent with a very ancient
separation of the two floras. There is no evidence of present-day interchange of
species except by the intervention of man. Trans-oceanic dispersal does not
seem possible now and there is little likelihood of an interchange with any
warmer land mass after Australia resumed its drift 140 m.y. ago, whilst
evidence is lacking for a possible interchange with India before that date. To
86
R. MELVILLE
the north was an oceanic barrier which was not breached until the late
Oligocene contact with New Guinea, and to the south the adjacent part of
Antarctica must have had a temperate climate before separation in the final
episode of drift. Antarctica could not have formed a land bridge for any
tropical invaders, and it shared in the general Gondwana flora in the Permian
as shown by the fossil record. The conclusion must be reached that the
characteristic Australian flora-excluding the Indo-Malaysian element of
relatively recent origin-must have evolved in situ from ancestors of Permian
age.
Acceptance of this conclusion implies that evolutionary trends in many
families, such as Proteaceae, Restionaceae, Leguminosae and Compositae, must
have been initiated already in the Permian for the observed parallel evolution to
have taken place subsequently on separated Gondwanic fragments. The
Permian ancestors of these families were not yet Angiosperms, but their
gymnospermous reproductive structures must have been capable of condensation and conversion into the components of an Angiosperm flower. Recent
discoveries of glossopterid fructifications have shed much light on this problem
and it is possible to anticipate how the male fructifications of Eretmonia could
have been transformed into the androecium of the Proteaceae. Haber’s study of
the floral vascular anatomy of the family indicates three types of stamen with
one, two or three traces respectively. The interpretation she gives of the paired
stamen-traces of Persoonia, Hakea and Telopea as originating from the median
tepal trace is open to question. Her conclusions were based upon serial sections
of flowers, a technique which does not always elucidate the finer details of
vascular connections. By using the chloral hydrate clearing technique, I was
able to establish in Persoonia elliptica that the two traces are attached to the
lateral tepal traces and not to the median trace. This brings Persoonia into line
with Eretmonia species in which a similar method of attachment of the
sporangial trusses is observed (Fig. 8).
Further work is necessary on floral anatomy in the Proteaceae to make a
critical check on the exact mode of attachment of the stamen traces, since this
is evidently of critical importance in the interpretation of floral evolution in
the family. Despite the remarkable range of leaf form, hitherto little attention
has been paid to leaf architecture in the Proteaceae and much more study is
necessary before a comprehensive assessment of leaf evolution in the family can
be made. Two of the main trends have been illustrated in Fig. 7, but there is
much parallel evolution and a number of side lines must be integrated. One of
these has been included in the figure to correct an earlier statement (Melville,
1973) that the leaf segments of Stirlingia teretifolia Meissn. and its allies
enclosed a single vascular strand. In these Stirlingias and in Isopogon villosus
Meissn. (Fig. 7 ) , the leaf segments contain fascicles of dichotomous strands,
showing double-Y forks at the dichotomous sinuses. The reason for this
arrangement is the same as in Petrophile curduacea Meissn. (Fig. 7 ) referred to
above, but the Stirlingia type of leaf appears to be a direct derivative of the
photosynthetic dichotomous branch system of the Psilophytes. The alternative
of segmentation of a gangamopteroid leaf seems less likely, as I have found no
evidence that the Stirlingia type has been derived from a planated leaf. On
either interpretation these would be extremely primitive relicts.
The inter-relationships of the genera and higher taxa within the Proteaceue,
AUSTRALIAN RELICT PLANTS
a7
as worked out by Johnson & Briggs (1975) primarily on floral characters,
indicate a high degree of parallel evolution within the family. The evidence
from leaf evolution also indicates considerable parallelism. The two lines of
evidence do not conflict as Johnson & Briggs (1975) seem to fear, and trends in
leaf evolution follow along the lines of the taxonomic groupings shown in their
dendrograms. The two points that cannot be reconciled with the evidence are
mainly theoretical. These are their concept of the protoProteaceous ancestor
and their repudiation of some of Haber’s evidence on floral anatomy.
The quotation from Hamshaw Thomas with which this paper opened
advocated a re-examination of the whole of Angiosperm morphology. The
advice was timely for evolutionary studies had been concentrated mainly on
floral morphology and anatomy and scant attention had been paid to vegetative
organs. The integration of these two lines of evidence is leading to a deeper
understanding of evolution in the Angiosperms. The new discoveries of
Glossopterid fructifications have revealed some of the structures postulated as
basic elements of the flower as interpreted by the gonophyll theory (Melville,
1960, 1963). By correlating this palaeobotanical evidence with floral vascular
matomy in the Proteaceae, some puzzling features which had led to the
divergent interpretations of Haber and of Johnson & Briggs are seen to conform
to Haber’s views and elucidate some of the evolutionary trends in the family.
ACKNOWLEDGEMENT
I am much indebted to Dr J. W. Pickett of the Geological & Mining Museum,
Sydney, N.S.W., for providing photographs of Walkom’s fossils on which
Fig. 3A was based.
REFERENCES
ANDREWS, E. C., 1916. The geological history of the Australian flowering plants. A m . J. Sci., 4 2 :
171-2 32.
AXELROD, D. I., 1952. A theory of angiosperm evolution. Evolution, 6: 29-60.
BESSAIRIE, H., 1946. La g6ologie de Madagascar. Annlsgiol. Serv. Mines, Madagascar, 12.
BURBIDGE, N. T., 1960. The phytogeography of the Australian region. Aust. J. Bor., 8: 75-209.
CREER, K. M., 1964. A reconstruction of the continents for the Upper Palaeozoic from palaeomagnetic
data. Nature, 203: 11 15-20.
CREER, K. M., 1970. Review and interpretation of Palaeomagnetic data from the Gondwanic continents.
Proc. 2nd Gondwana Symposium, S. Africa: 55-72.
CROIZAT, L., 1966. L’age des Angiospermes en g6nCral et de quelque Angiospermes en particulier.
Adansonia, 6: 21 7-42.
DU TOIT, A. L., 1937. Our wandering continents. Edinburgh: Oliver & Boyd.
ETTINGSHAUSEN, C. R. VON, 1861. Die Blart-Skelere der Dicotyledonen. Vienna: Staatsdruckerei.
FEISTMANTEL, 0. 1881. Mem. geol. Surv. India Palaeont. indica, 3 , 3 9 A : fig. I A .
HABER, J . M., 1960. The comparative anatomy and morphology of the flowers and inflorescences of th e
Proteaceae. I. Some Australian t a m . Phytomorphology. 9: 325-58
HEIRTZLER, J . R., VEEVERS, J. V. e t al., 1973. Age of the floor of the eastern Indian Ocean. Science,
180: 952-4.
HOLMES, W. B. K., 1974. On some fructifications of th e Glossopteridales from the Upper Permian of
N.S.W.Proc. Linn. SOC.N.S.W., 98: 1 3 1 4 1 .
JONES, J. G., 1971. Australia’s Caenozoic drift. Nature, 230: 237-9.
JOHNSON, L. A. S. & BRIGGS. B. G., 1963. Evolution in the Proteaceae. Aust. J. Bot., 1 1 : 21-61.
JOHNSON, L. A. S. & BRIGGS, B. G., 1975. On the Proreaceae-the evolution and classification of a
southern family. Bot. J. Linn. SOC.. 70: 83-182.
KING, L., 1973. A n improved reconstruction of Gondwanaland. In D. A. Tarling & S. K. Runcorn (Eds),
Implications of continenral drift to the earth sciences, 2: 851-63.
R. MELVILLE
88
LACEY, W. S., VAN DIJK, D. E. & GORDON-GRAY, K. D., 1974. New Permian Glossopteris flora from
Natal. S. Afr. J. Sci., 70: 154-6.
LARSON, R. L. & LADD, J . W., 1973. Evidence for the opening of the South Atlantic in the early
Cretaceous. Nature, 246: 209-12.
McELHINNY, M. W., 1973. Earth sciences and the Australian continent. Nature. 246: 264-8.
MELVILLE, R., 1952. Two allies of Epacris heteronema Lab. K e w Bull., 7: 175-8.
MELVILLE, R., 1960. A new theory of t h e angiosperm flower. Nature, 188: 14-8.
MELVILLE, R., 1963. A new theory of the angiosperm flower 11. K e w Bull., 17: 1-63.
MELVILLE, R., 1969. Leaf venation patterns and the origin of the angiosperms. Narure, 244: 121-5.
MELVILLE, R., 1971. Some general principles of leaf evolution. S. Afr. J. Sci., 67: 310-6.
MELVILLE, R., 1973. Relict plants in the Australian flora and their conservation. In A. B. Costin & R. H.
Groves (Eds), Nature conservation in the Pacific Canberra: Aust. Nat. Univ. Press.
MOORE, J. S., 1936. Vascular anatomy of the flower in the papilionaceous Leguminosae 1. A m . J . Bot..
23: 279-90.
NEWMAN, L. V., 1936. The meristematic activity of the floral apex of Acacia longifolia and A .
suaveolens as a histogenic s t u d y of the ontogeny of the carpel. Proc. Linn. Soc. N.S. W., 61: 56-88.
PLUMSTEAD, E. P., 1958. Further fructifications of the Glossopteridae and a provisional classification
based o n them. Trans. Geol. Soc. S. Afr., 6 1 : 51-76.
PLUMSTEAD, E. P., 1967. A general review of the Devonian fossil plants found in the Cape System of
South Africa. Palaeont. Afr., 10: 1-83.
PLUMSTEAD, E. P., 1969. Three thousand million years of plant life in Africa. A. L. Du Toit Mem. Lect.
No. 1 1 . Transgeol. SOC.S. Afr., 7 2 (Annex): 1-72.
REYMENT, R. A,, 1969. Ammonite biostratigraphy. continental drift and oscillatory transgressions.
Nature, 244: 137-40.
SINGLETON, F. A., 1941. The tertiary geology of Australia. Proc. R. Soc. Vict., 5 3 : 1-118.
SMITH, A. G . , BRIDEN, J. C. & DREWRY, G . E., 1973. Phanerozoic world maps. In N. F. Hughes (Ed.).
Organisms and continents through time Syst. Ass. Publs, 9: 1-39.
SMITH, A. G. & HALLAM, A,, 1970. The f i t of t h e southern continents. Nature, 225: 139-44.
SPECHT, R. L., ROE, E. M. & BOUGHTON, V. H., 1974. Conservation of major plant communities in
Australia and Papua New Guinea. Aust. J . Bot., Suppl. 7 : 606-28.
SURANGE, K. R. & CHANDRA, S. 1974. Some male fructifications of Glossopteridales. Palaeobotanist,
21: 255-66.
TARLING, D. H., 1972. Another Gondwanaland. Nature, 238: 92-3.
THOMAS, H. H., 1958. Palaeobotany and the evolution of the flowering plants. Proc. Linn. Soc. Lond.,
169: 135-43.
THOMAS, 11. H., 1961. The evolution of the Angiosperms: historical and ecological evidence. Proc. Linn.
Soc. Lond., 1 7 2 : 1-6.
TUCKER, S . C. & GIFFORD. E. M., 1964. Carpel vascularisation of Drimys lanceolata. Phytomorphology.
14: 197-203.
WALKOM, A. B., 1921. On Nummulospermum, Gen. nov., the probable megasporangium of Glossopteris.
Quart. J . Geol. Soc.. 7 7 : 289-95.
WALKOM, A. B., 1928. Notes o n some additions to the Glossopteris flora in N.S.W. Proc. Linn. Soc.
N.S. W..5 3 : 555-64.
WEISSEL, J . K. & HAYES, D. E., 1971. Asymmetrical sea floor spreading south of Australia. Nature,
231: 518-22.
WELLINGTON, J. H., 1955. Southern Africa: a geographical study, 1 : 460-73. Cambridge: Cambridge
University Press.
WHITE, M. E., 1963. Reproductive structures in Australian Upper Permian Glossopterideae. Proc. Linn.
SOC.N.S. W . , 88: 392-6.