Bot. J. Linn. SOC.,62, pp. 169-186. With 1 plate and 5 Jigures
April 1969
On the relationships of Emblingia
G. ERDTMAN
Palynologiska Laboratoriet, Solna, Sweden
P . LEINS
Institut fur Systematische Botanik, Munich, Germany
R. MELVILLE, F.L.S.
The Herbarium, Royal Botanic Gardens, Kew
AND
C. R. METCALFE, F.L.S.
Jodrell Laboratory, Royal Botanic Gardens, Kew
Accepted.for publication August 1968
Examination of the pollen morphology, floral morphology and anatomy, and vegetative
anatomy of Emblingia calceoliflora F. Muell. leads to widely divergent views concerning its
systematic affinities.
Erdtman considers that pollen morphology shows Emblingia should be referred to, or near to,
Polygalaceae; the pollen grains are unlike those of Capparaceae, Goodeniaceae or Sapindaceae.
Leins concludes that Emblingia is probably allied to the Sapindaceae. He lists the following
similarities : three-carpellate, septate ovary with one axile ovule in each loculus ; short androgynophore ; eccentric, extrastaminal disk; reductions in corolla and androecium; ventral
appendages to petals ; spiral embryo and aril ; bitegmic and crassinucellate ovules.
Melville interprets the hood of the androgynophore of Emblingia as a third petal and the
gland (‘disc’) as a reduced stamen fascicle; the floral parts show a tendency to adhesion such as
is common in the Goodeniaceae. Emblingia resembles Scaevola in general habit and hair type;
the trimerous ovary, stigmatic vascular brush, and reniform seeds with curved embryos and
complex vascular supply also suggest an affinity with Goodeniaceae.
Metcalfe’s examination of the leaf and stem anatomy of Emblingiu shows that the histological
resemblance is closest to Goodeniaceae and next closest to Polygalaceae. Similarities to
Goodeniaceae include minutely warty, unicellular hairs ; branched sclereids ; vascular bundles
of leaf sheathed by inflated parenchymatous cells; deep-seated origin of cork in stem; xylem
forming a closed cylinder in stem, traversed by narrow rays; mostly solitary vessels with simple
perforations.
CONTENTS
Introduction (by G. Erdtman)
The pollen morphology of Emblingiu (by G. Erdtman)
Material examined
Pollen morphology
Apertures. Fine structure of the exine .
Orientation of the flower .
Affinities
.
.
.
PAGE
.
170
.
.
.
.
.
170
171
171
171
172
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
170
The floral morphology of Emblingia (by P. Leins)
Material examined
Observations
The floral diagram
Discussion
.
.
.
.
The floral vascular system of Emblingia (by R. Melville)
Introduction
Material examined
Orientation of the flower .
Cleared specimens .
Discussion
.
Summary.
.
.
.
Anatomy of stem and leaf of Emblingia (by C. R. Metcalfe)
Material examined .
Leaf
T.S. stem.
Conclusions
Acknowledgement .
References
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
172
172
174
174
175
175
175
176
178
181
182
182
183
183
185
185
INTRODUCTION (by G.E.)
I n 1860 F. Mueller described a new member of the Australian flora, Emblingia
calceoliflora, a small shrub which he categorically referred to the Capparaceae in spite
of some strange details in its flowers. There it still remains as far as handbooks and
local floras are concerned.
Emblingia has been found only in Western Australia in the Irwin district northnorth-west of Perth. Herbarium specimens are very rare, particularly outside
Australia. For this reason it has been difficult to reinvestigate Emblingia more minutely.
However, in 1954 one of u s managed to publish a short account of the morphology
of its pollen grains. These are of a unique type, entirely different from the pollen
types so far encountered in the rest of the Capparaceae. I t was vaguely intimated,
however, that its pollen morphology suggested the Polygalaceae. Later on, anatomy
and finally certain floral details were investigated by the other three in the team.
The results herewith published show that we have arrived at different conclusions
regarding the taxonomic affinities of Emblingia. This is an indication that the Emblingia
problem is one of extreme difficulty. Will the anatomical, the floral or the pollen
morphological ideas prove to be correct ? Or will it turn out that all of us have failed ?
The pollen morphology of Emblingia
G. ERDTMAN
MATERIAL EXAMINED
Emblingia calceoliflora F. Muell. (i) Greenough River, W. Australia, 1877, F. von
Mueller. (ii) 15 miles north of Carnamut, W. Australia, 8 Feb. 1954, Stuart. (iii)
Gunyidi, W. Australia, August 1959, A. Baird. Specimens examined are in the
Melbourne (i) and Perth (ii, iii) Herbaria.
RELATIONSHIPSOF EMBLINGIA
171
POLLEN MORPHOLOGY
T h e pollen grains in the Capparaceae are, as far as we know, so unlike the large
peculiar pollen grains, with an equatorial diameter c. 60 p, encountered in Emblingia
(Plate l), that a somewhat close relationship between the two taxa hardly seems likely.
The pollen grains in the Polygalaceae also differ from those in Emblingia, because the
grains are usually considerably smaller and there are always more than three furrows.
On the other hand there are certain details in common: the ora are lalongate and very
distinct, which seems to account for the fact that the sexine (surrounding, inter aka,
the faint outer, colpal, part of the apertures) is distinctly thinner-at least in the
mesocolpia-than the nexine. A reduction in the number and length of the furrows
in the pollen grains of Polygala vulgaris would, in conjunction with an increase in the
size of their apocolpial thin-walled depressions, lead to the formation of two thinwalled polar areas which gradually merge with the thick-walled equatorial zone.
Thcse changes would lead to pollen grains of much the same type as those in Emblingiu.
This similarity, together with the occurrence in the floral region of Emblingia of small
hairs of the same type as occur in the Polygalaceae, makes me inclined to retain my
original idea that Emblingia should possibly be referred to, or placed near the Polygalaceae. This idea is further substantiated by some of the facts mentioned by D r
Leins : androecium octomerous (four fertile stamens, four staminodes), ovary threelocular with axile placentation (one ovule in each loculus).
APERTURES. FINE STRUCTURE O F T H E EXINE
A re-examination of some pollen slides has revealed the presence of a single fourcolporate grain (Stuart s.n.) and several small abortive pollen grains with one or two
apertures (3‘.von Mucller s.n.).
Considerable difficulties were encountered in attempting to apply electron microscopy for elucidating the fine structure of the sporoderm in non-acetolyzed pollen
grains taken from poor and scanty herbarium material. Some EMG-s indicate, however, in conformity with observations made by ordinary light microscopy, that the
supposed sexine is much thinner than the nexine. Contrary to the findings by Larson
& Skvarla (1961) in Polygulu, the electron density of the exine is the same throughout
except perhaps in a very thin ‘nexine 2’. This description seems to hold good at least
as far as the equatorial parts of the mesocolpia are concerned. T o the ‘nexine 2’
probably also belong a number of detached, tangentially elongated fragments
embedded in the outer part of the intine.
ORIENTATION O F T H E FLOWER
When I first dissected a flower of Emblingia (December 1954), I got the impression
that the calyx of fully developed flowers was open (bifid) in the adaxial part of the
flower. I n contradistinction to the description given in the original diagnosis of the
species the torus thus had to be adaxial and the ‘calceolus’ abaxial. As there was some
doubt, however, I wrote to Mrs Kathleen McWhae, of Perth, Western Australia,
172
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
asking for further information. My letter was unfortunately mislaid and only found
seven years later. In her reply (October 1963) Mrs McWhae kindly informs me that
observations made on a specimen collected by Miss Alison Baird (Perth) at Gunyidi,
W.A., are in accord with my preliminary findings: in the letter is a sketch of a flower
showing an adaxial torus and an abaxial ‘calceolus’.
AFFINITIES
The very peculiar, large, three-colporate (to occasionally four-colporate or more
or less irregular) pollen grains in Emblingia have practically no characteristic features
in common with those in the Goodeniaceae, e.g. in Scaevola. The pollen grains of
Emblingia are also very unlike those of the Sapindaceae. Nevertheless, in spite of these
differences, Dr. Leins accepts Professor Merxmuller’s conception of a relationship
between Emblingia and the Sapindaceae.
If the new evidence given above is sufficiently trustworthy it would appear to
weaken the argument for treating Emblingia as if it were a member of the family
Polygalaceae itself. In these circumstances I can only summarize my views concerning
the taxonomic position of Emblingia in the following way. Of the possibilities that are
open to us, it would be most reasonable to place Emblingia in a distinct family, the
Emblingiaceae, which must be closely related to the Polygalaceae. A second possibility
would be to treat Emblingia as a subfamily of the Polygalaceae to be known as the
Emblingioideae. If there is a relationship with the Sapindaceae it must be regarded
as very remote and there is still less evidence in favour of a connection with the
Goodeniaceae.
The flower morphology of Emblingia
P. LEINS
MATERIAL EXAMINED
Flowers of Emblingiu calceolijlora F. Muell. from three herbarium specimens (Gardner 9388; Baird anno 1959; Chadwick anno 1965) have been examined. Besides preparing and examining the material under a stereomicroscope, the author embedded
a young flower and floral parts (especially the gynoecium) in paraffin and sectioned
them.
OBSERVATIONS
The flowers of Emblingia have five sepals. These are connate for about half of their
length, except the two abaxial ones, which are separate from each other right down
to the base, The slipper-like corolla consists of two petals (Fig. 1A-L) interconnected
only by their cuticles. Their upper and lowermost parts are free from each other.
The petals alternate with the three adaxial sepals in the floral diagram ;ventrally their
lower part is provided with two narrow, ribbon-like appendages (Fig. 11, J).
G
\..
-
: :<
.::
....
H
9Y
B
di
K
di
ov
D
F
vM
FIGURE
1. A-L. Emblingia calceoliflora. Some cross-sections through a young flower from top
to bottom (the sepals were removed before the embedding). M. Theoretical floral diagram.
an, Androgynophore; di, disk; gy, gynoecium; ov, ovules; p, petal; st, stamens; sti,
stigma; sto, staminodes.
174
G . ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
There are four fertile stamens, all in the adaxial part of the flower (Fig. 1B). In
the abaxial part there is a four-or five-lobed torus. In cross-section the lobes show the
same histological features as the filaments of the fertile stamens, Accordingly the
torus seems to represent four or five staminodes connate in their lower part (Fig.
1C-E). The stamens and the staminode torus are interconnected at the base and
are inserted on a conspicuous androgynophore (Fig. 1F-J, an; the filaments of the
two interior stamens are fused only for a very short distance). At the base of the
androgynophore there is a disk, triangular in cross-section, between the two petals
(Fig. lK, L).
The ovary on top of the androgynophore has two transverse wings below the
sessile stigma (Fig. 1A). I n contrast to the observations of Mueller (1860-1) the
ovary is trilocular (not unilocular) and possesses not one but three ovules, one in each
loculus. Perhaps only one ovule develops into a seed. The placentation of the threecarpellate, septate ovary is axile (Fig. 1D). Microtome sections show that the ovules
are crassinucellate and provided with two integuments. For more detailed studies
fresh material would be necessary.
THE FLORAL DIAGRAM
In the theoretical diagram (Fig. 1M) the androecium is drawn as being diplostemonous (two median stamens are lacking, viz. the adaxial one of the outer episepalous whorl and the abaxial one of the inner epipetalous whorl). Four of the remaining
eight members of the androecium are fertile, the other four staminodial. The corolla
is thought of as consisting basically of five petals, three of which have aborted.
DISCUSSION
Mueller (1860-1) has described Emblingia as a genus of the Capparideae group.
Since that time several other authors have included this genus in the Capparaceae.
Recently Erdtman (1954) proposed a relationship between Em6lingia and the Polygalaceae, basing his conclusions mainly on pollen morphological investigations.
What can the floral morphology tell us about the relationships of Emblingia? Let
us first compare the facts recorded above with the floral features in the Capparaceae
and the Polygalaceae. There is an important argument against the relationship between
Emblingia and the Capparaceae, viz. the fact that Emblingia has a septate ovary with
axile placentation, whereas the Capparaceae are distinguished by unilocular ovaries
with parietal placentation as in the related Parietales. The septate gynoecium with
only one ovule in each loculus is more characteristic of the Polygalaceae. In this
family we also meet an androecium consisting of eight stamens (the median members
of the two-whorled androecium are lacking). I n the polygalaceous genus Salomonia
the calyx looks almost like that of Emblingia (the synsepalous calyx has a fissure at its
abaxial side). In Emblingia there are thus a few characteristics which also occur in the
Polygalaceae. We must, on the other hand, consider the fact that an androgynophore,
as met with in Emblingia, is very unusual in the Polygalaceae.
Professor Merxmuller kindly directed my attention to another Pinnatae group,
which in its floral morphology shows more accordancewith Emblingia: the Sapindaceae.
RELATIONSHIPS
OF EMBLINGIA
175
In this family the following similarities often or occasionally occur : a three-carpellate,
septate ovary with only one axile ovule in each loculus; a short androgynophore
(Serjania leptocarpa) ; reduction in the diplostemonous androecium (eight stamens) ;
an eccentric, extrastaminal disk; reductions in the corolla; ventral appendages to the
petals (Leinfellner, 1958). The development of only one of the three ovules into a
seed (occasionally in Paullinia) and the occurrence of an aril and a spiral embryo are
facts that would also agree with the characteristics of the fruit and seed in Emblingia
as drawn by Mueller (1860-1).
The presence of bitegmic and crassinucellate ovules in Emblingia does not favour a
relationship between this genus and the Goodeniaceae, as is suggested by Dr Melville
and Dr Metcalfe. T h e Goodeniaceae have unitegmic and tenuinucellate ovules (RosCn,
1946, Davis, 1966, and my own investigations).
These facts without doubt support the conclusion that Emblingia is probably allied
to the Sapindaceae.
The floral vascular system of Emblingia
R. MELVILLE
When Mueller described Emblingia he felt confident that the plant belonged to the
Capparaceae on account of the presence of an androgynophore and the curved embryo
of the seeds. At the same time he observed that in its habit Emblingia resembled some
species of Scaevola in the Goodeniaceae. The androgynophore is not a simple structure like that of the Capparaceae, while the curved embryo of the seeds is paralleled
in the families of the Centrospermae and also in the section Camptospora of Dampiera
in the Goodeniaceae. Suggestions that Emblingia might be related to the Polygalaceae
or alternatively to the Sapindaceae called for a critical examination of the floral
structure.
MATERIAL EXAMINED
The investigation had of necessity to be carried out on herbarium material and I
am greatly indebted to Mr R. D. Royce of the State Herbarium, Perth, for the loan
of specimens. Owing to the scarcity of material only one bud, one open flower, one
fruit and one shoot tip could be examined in detail, but these have provided a number
of fresh characters.
Emblingia calceoliflora F. Muell. (i) Three Springs, S. of Lake Legue 25.8.1949,
C. A. Gardner 9388. (ii) Cockleshell Gully, Feb. 1940, C. A. Gardners.n. Clearing
for microscopical study was done by chloralhydrate.
ORIENTATION OF T H E FLOWER
At anthesis the floral pedicel may be spreading or reflexed, when the flower itself
is then bent upwards parallel with the pedicel (Fig. 2G). No twisting of the pedicel
could be detected in either dry or cleared flowers. The five calyx lobes are united for
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
176
about half their length, except on the adaxial side where the calyx tube is split to the
base (Fig. 2A, G). T h e odd sepal is abaxial. T h e two petals are abaxial, alternating
with sepal lobes, and they face towards the split in the calyx tube. Their hooded tips
overlap the hood of the androgynophore, which is facing towards the petals and
away from the sepaline gap (Fig. 2A). I n most of the flowers on the specimens
examined the hood of the androgynophore was three-lobed (Fig. 2F), but in the bud
FIGURE
2 . Emblingia calceoliflora F. Muell. A, Mature flower bud, adaxial side. B, C. Tip of
androgynophore; B, uncleared, two anthers removed, one staminode present; C, cleared showing vascular supply to stamens and ovary. a, stamen traces. D. Vascular supply to hood of
androgynophore. E. Union of the hood traces and relationship to adjacent sepal traces. s,
sepal traces. F. Tip of another androgynophore with three lobes and showing placental,
dorsal and stigmatic traces of the ovary. G. Lateral view of a flower after petal fall, calyx split
to base at left.
four lobes were present and the fruit had five lobes. T h e somewhat enlarged persistent
filaments of the lateral stamens may appear like additional lobes in the fruiting state
(Fig. 3C) and must not be confused with the true lobes of the hood. Normally four
stamens are present, attached by short filaments to the abaxial side of the hood a little
below the ovary. One staminode and three stamens were present in the bud, anthers
of two of which have been removed in the drawing (Fig. 2B). At anthesis the ovary
is broadly winged and is capped by a more or less triangular sessile stigma (Fig. 2B,
c, F).
CLEARED SPECIMENS
T h e sepal midrib trace gives rise to two laterals near the base of the calyx tube
and the laterals branch and anastomose to give an open reticulum (Fig. 3A). T h e
RELATIONSHIPS
OF EMBLINGIA
177
median sepal traces pass downwards to the base of the pedicel, remaining separate.
The petals have three main traces, branches of which give an open reticulum and
dichotomize near the apex. T h e laterals produce pendent branches near the base of
the petal (Fig. 3B). T h e petals adhere loosely to one another, but are soon deciduous.
Their lateral nerves join the median petal trace above or just below the point of
abscission (Fig. 3A). T h e common petal traces then pass down to the base of the
pedicel parallel with the adjacent sepal traces (Fig. 3A). I n the specimen illustrated the
--FIGURE
3 . Emblingia calceolij7ora. A. Vascular system of sepal and relationships of sepal and
petal traces; s, sepal trace; p, petal trace. B. Vascular system of petal. C.Young fruit inverted
inside calyx, hairs omitted; a, stamen filament. D. Placental vascular supply of fertile loculus
with vasculature of wall attached. E. Wall of loculus dissected and turned back to show supply
to ovule; pl, placental trace; d, dorsal trace. F. Floral diagram.
hood of the androgynophore seen in adaxial view (Fig. 2D) had four traces each
terminating in one of the lobes. Near the base of the androgynophore these traces
came together in pairs and the two traces united into a single trace in the upper part
of the pedicel and then continued downwards parallel with the adjacent sepal traces
to its base (Fig. 2E). Viewed from the abaxial side, four slender traces could be seen
running from the stamens to the base of the androgynophore where they fused in
pairs. T h e traces of either side then approached closely the trace of their adjacent
anterolateral sepal in the upper part of the pedicel. No fusion was observed and the
two stamina1 traces appeared to continue towards the base of the pedicel very close
178
G . ERDTMAN,
P. LEINS,R. MELVILLE
AND C . R. METCALFE
to their sepal traces. T h e three traces to the gynoecium can be seen most clearly from
the abaxial side. They continue round the periphery of the ovary to the base of the
sessile stigma where each bifurcates and sends off a number of more or less parallel
branches to give rise to a vascular stigmatic brush (Fig. 2C, F). I n the base of the
ovary, a placental branch arises from each of the dorsal traces and passes upwards in
the axile position into the middle of the ovary (Fig. 2F). T h e fruit remains reflexed
inside the calyx, but only one ovule develops. T h e wall of the fertile loculus has a
reticulate nervation, the stouter branches of which are attached to the placental trace
(Fig. 3D) and much weaker ones to the dorsal trace (Fig. 3E). Inside, the reniform
ovule is supplied by a stout funicular branch, which breaks u p into a fan of coarse
irregular strands, but a single slender rather short arched trace was also observed
(Fig. 3E).
DISCUSSION
With the details of the vascular system now available it is possible to form an opinion
as to the nature of the hood of the androgynophore. It is clear that it does not represent
a group of staminodes, as the position and relation of the vascular system to that of
the sepals is different from that of the staminal traces. On the other hand, the hood
traces do take up a position like that of the petals and the conclusion is reached that the
hood represents a third petal which has become fused to the androgynophore in the
course of its evolution. T h e great similarity of the indumentum of hood and petals is
consistent with this idea. The flower therefore consists of five sepals with the odd
one anterior and the hood is the median posterior petal. T h e two posterolateral petals
are absent and the two surviving ones are the anterolaterals. T h e four surviving
stamens represent two reduced stamen fascicles related to the anterolateral sepals.
The gland which lies between the petals and the androgynophore does not appear to
have retained any vascular supply, but it is in the position of a member of the androecium and could represent the much reduced staminal fascicle of the anterior sepal.
T h e other two representatives of the androecial whorl would have been suppressed at
the stage of evolution when the hood fused with the androgynophore (Fig. 3F).
T h e trimerous ovary has the odd member posterior.
Mueller’s initial comparison of Emblingia with Scaevola aemula R. Br. was no
doubt based on his field observations and appears to have been much nearer to the
truth than his later judgment of an affinity with the Capparaceae. This species and
several others recall the habit of Emblingia and in the course of this study it was noted
that several species have warty-surfaced hairs with a plinth of enlarged epidermal
cells at their base reminiscent of the peculiar hairs described by Metcalfe for Emblingia.
These include S. aemula, S. phlebopetala F. Muell., S. hillii Gard. and S. glandulifera
DC. It is clear that the androgynophore of Emblingia bears very little resemblance
to that of the Capparaceae. Within the affinity of the Goodeniaceae this structure
can be regarded as another expression of a general tendency for adhesion to occur
within and between the several floral whorls. Sepals, petals and stamens may be
free from one another or fused within the whorl. Sepals may be fused to varying
degrees with petals or ovary or both, and staminal filaments may be fused to petals
RELATIONSHIPS
OF EMBLINGIA
179
for part of their length. T h e fusion of a petal with the androecium and gynoecium in
Emblingia does not greatly extend this range and the fact that the other two petals
are free to the base (though adherent) is paralleled by the slit corollas of several
genera of Goodeniaceae. Meristic variation is also a feature of the Goodeniaceae, for
example some species of Velleia have five sepals and others three. Some meristic
variation may occur within species as in the example mentioned below. T h e hood petal
of Emblingia may have three to five lobes with corresponding changes in the vascular
system. Characteristically the petals in Goodeniaceae are three-nerved, but the specimen of Dampiera alata Lindl. examined in the course of this study had three to five
and this kind of variation may not be uncommon in the family. Emblingia does not
appear to be out of place in this meristically unstable group.
Turning now to the gynoecium, although the gynophore is unprecedented the
trimerous ovary of Emblingia compares with dimerous and trimerous ovaries in various
goodeniaceous genera and a possible ancestral condition of tetramery (Carolin, 1959).
The apposition of three gynophylls with axile placental strands may at first recall
the Sapindaceae, but in that family the gynophyll blades forming the ovary wall are
valvately arranged and often imperfect septa are formed by ingrowths (Melville,
1962). There may be a short gynophore with stamens partly fused to it, as in Cardiospermum, but the vascular connections of these parts are differently arranged from
those of Emblingia. T h e vascular supply to the style and stigma in the Sapindaceae
consists of simple traces bearing no resemblance to the vascular stigmatic brush of
Emblingia. On the other hand the stigmatic brush of Emblingia (Fig. 2C, E, F) is
remarkably like that of the Goodeniaceae. Compare for example those of Leschenaultia
(Fig. 4E) and Dampiera (Fig. 4C). There are even fewer similarities between the
vascular construction of the flower in the Polygalaceae than in the Sapindaceae.
It is likely that Mueller did not know of the occurrence of reniform seeds with
curved embryos in the Goodeniaceae when he wrote his account of Emblingia. T h e
seeds of several of the species of Dampiera section Camptospora, in which such seeds
are found, were still unknown nine years later when Bentham published his account
of the family in Flora Australiensis (1869). A flower of D . alata Lindl. was examined
as an example of this group. The ovule was found to possess a complex vascular
system of recurved strands (Fig. 4D) comparable with that reported €or D . coronata
Lindl. by Carolin (1966). T h e ovule system was connected with a rather irregular
placental system which made attachments with several of the sepaline traces. T h e
ovule appears to be wrapped around the placenta, which projects into the ovary like
a false septum. Emblingia differs widely from this, but the Dampiera condition could
be derived from that of Emblingia by further relative enlargement of the ovule causing
overgrowth over the whole of the placental region. I know of nothing comparable
with these structures in either Sapindaceae or Polygalaceae. The single encircling
strand in the ovule of Emblingia (Fig. 3E) may be compared with the encircling and
recurved strands of D. alata or better still with the simple encircling strands found in
other genera such as Leschenaultia, Goodenia and Velleia (Carolin, 1966).
Fortuitously the flower of D . alata which was cleared happened to possess six
sepals, six petals and six stamens and in the ovary there was a third dorsal trace
which reached only to the base of the style (Fig. 4D). This is an example of the
13
180
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
tendency to meristic variation in the Goodeniaceae already referred to, and it proved to
be of particular interest in the present context. In this hexamerous calyx there were
..
.
FIGURE
4. A-D. Dampiera alata Lindl. A, B. Lateral views of sepals and petal bases of the
two sides showing the arrangement of the six sepals of this flower; p, groups of petal traces.
C. View of flower, petals removed; a, stamen traces. D. Part of ovary wall removed to show
vascular supply to ovule; s, sepal traces; d, dorsal traces. E. Stigmatic vascular system of
Leschenaultia formosa R. Br.
FIGURE
5. A-C. Scaevola depauperata R. Br. A. Lateral view to show the association of bract
and floral pedicel traces in the stem. B. View from inside. C. External view showing the three
traces of the bract. D. Emblingia calceoliflora, stipules stippled, showing association of stipule
traces, floral pedicel trace and the single leaf trace in the stem. 1, Leaf trace.
odd sepals in both anterior and posterior positions and a pair of sepals at either side.
From a condition like this, it would be equally easy for the situation found in Emblingia
to evolve, with the odd sepal anterior, as for that found in typical Goodeniaceae, with
RELATIONSHIPS
OF EMBLINGIA
181
the odd sepal posterior. It does not seem necessary to place much stress on the
character of floral orientation when assessing the possible relationship of Emblingia to
the Goodeniaceae. It is perhaps worth noting that the sepals of D.alata (Fig. 4B)have
pendent lateral branches in their vascular system which may be compared with the
pendent laterals of Emblingia petals.
In his account of Emblingia, Mueller made no mention of stipules, yet at the base
of every petiole a pair of yellow, fleshy conical protuberances is to be seen which
can only be interpreted as stipules. These structures develop precociously in the bud
and at an early stage are as large as the leaf itself. I n a cleared preparation (Fig. 5D)
it can be seen that a slender trace leaves the base of each of these and passes down the
stem close to and parallel with the single stout petiolar trace and the trace from the
flower bud. These four traces remain together as a unit distinct from the remaining
vascular tissue of the stem for at least one internode. Stipules are not known in either
the Goodeniaceae or the Polygalaceae and are reported from the Sapindaceae only
from Serjania, Paullinia and Urvillea, none of which appears to bear any other resemblance to Emblingia. There are some general resemblances between the stem structures in the Goodeniaceae and Emblingia which can be demonstrated in Scaevola
depauperata R. Br. T h e manner in which the pedicel traces are associated with the
leaf traces is similar (Fig, 5A) and the group of traces runs down the stem separate
from the stem vascular system for at least one internode in the same way. T h e bracts
have three main traces, but instead of the two laterals fusing with the median, as they
do in many families, they run on down the stem as separate entities for at least the
first internode (Fig. 5 B, C). All that need happen to transform this condition into that
of Emblingia is for the leaf to become trilobed and the lateral lobes to specialize as
stipules, without involving any important change in the vascular supply. It appears
that on this score also Emblingia is not very far removed from the Goodeniaceae.
SUMMARY
The similarity of facies between Emblingia and Scaevola is supported by the presence
of the same unusual hair types in the two genera. T h e trimerous ovary with mile
placentation is consistent with an affinity with the Goodeniaceae ; the same type of
stigmatic vascular brush is shared. Reniform seeds with curved embryos occur in the
section Camptospora of Dampiera as well as in Emblingia; both have elaborate ovule
vascular systems which differ considerably from one another but have some features
in common. T h e vascular system and relationships of the hood of the androgynophore
indicate that it represents a third petal. T h e vascular traces of the four stamens unite
in pairs which are associated with the traces of the anterolateral sepals; in Goodeniaceae stamen traces are usually inserted on the sepal traces in the receptacle.
There are no staminodes except by occasional abortion of a stamen, unless the gland
between the petals and the androgynophore is accepted as staminodal. Stipules are
present in Emblingia though not in Goodeniaceae, but the vasculation of the stem is
very similar and the stipular traces of Emblingia correspond with the lateral traces of the
leaf in Goodeniaceae. Resemblance to the Sapindaceae is almost confined to the
trimerous ovary; other details of the construction of the flower are different. T h e few
182
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
sapindaceous genera with stipules are otherwise markedly different. There are few
similarities in floral construction to the Polygalaceae and this family does not appear
to be closely related. T h e balance of morphological and anatomical characters indicates
an affinity with the Goodeniaceae, but as there are several important differences
from this family, Emblingia is best treated as a distinct monotypic family.
Anatomy of stem and leaf of Emblingia
C. R. METCALFE
MATERIAL EXAMINED
Emblingia calceolifora F. Muell. (i) Murchison River, W. Australia, OldJield. (5)
W. Australia, Stuart. (iii) W. Australia, 1959, A. Baird. (iv) Three Springs, W. Australia, Gardner 9388. Specimens examined are all in the Kew Herbarium.
T h e structure of the leaf of Emblingia calceoliflora F. Muell. was studied in transverse sections through the lamina and through the distal end of the short petiole as
well as in surface view preparations of both the adaxial and abaxial epidermis. The
structure of the stem was likewise examined in transverse sections through internodes
and in longitudinal sections. All sections were cut on a sledge microtome without
embedding. It was necessary to prepare microscope slides from herbarium specimens
because no material was available that was more suitable for microscopical examination.
Because it was necessary to rely on dried material some details of the structure were
somewhat obscure, but nevertheless the preparations were of sufficiently good quality
to enable the more important histological characters of accepted taxonomic value to
be seen. The following is a description of the histology of the material examined.
LEAF
Surface view
Hairs present on abaxial surface ; unicellular, thick-walled, often tapered to pointed
apices, but others more uniform in width. Hairs often up to 240 p long and sometimes
longer, but frequently much shorter. Surface of hairs appearing to be densely and
minutely warty or to be covered with particulate material when examined in aqueous
mounts, but this character becoming obscure in balsam mounts. Hair bases mostly
surrounded by radiating rosettes of enlarged epidermal cells. Stomata ; present on
both surfaces; guard cells slightly below the level of the epidermis and with outer
cuticular lips ; apparently mostly anomocytic (i.e. surrounded by unspecialized
epidermal cells) but rather obscure in surface view in the material available.
T.S. lamina and petiole
Mesophyll; no very clear differentiation into palisade and spongy portions, but cells
towards both surfaces tending to be palisade-like ; tissue somewhat looser below
stomata than elsewhere. Isolated branched sclereids, with numerous short arms,
RELATIONSHIPS
OF EMBLINGIA
183
scattered throughout the mesophyll. (These sclereids were very numerous in all of the
specimens examined, with the exception of Gardner 9388.) Midrib abaxially prominent,
with flattened to slightly crescentiform vascular strand. Other vascular bundles
embedded in the mesophyll about midway between the adaxial and abaxial surfaces ;
vascular bundles sheathed by large, inflated, translucent cells, the cells usually
collapsed in slides prepared from dried specimens. Petiole, in transverse sections
through the distal end, supplied by a single crescentiform vascular strand with
incurved ends, but sometimes (e.g. in Baird s.n.) appearing to have an additional
vascular strand between the two ends of the crescent.
T.S. STEM
(Diameter of specimens examined 3.5-4 mm; diameter of pith 1-1.5 mm).
Epidermis; composed of very small cells standing out in marked contrast to the
much larger cells of the cortex. Hairs; similar to those on leaf; tapered from widest
part at level of epidermal surface to pointed apices. Cortex; composed of thin-walled
parenchyma, but with isolated, pitted sclereids embedded in it. Sclereids variously
shaped in T.S. but mostly square to trapezoid in L.S. A few branched sclereids,
similar to those in the leaf, also noted. Cork; arising in a deep-seated position in the
cortex. Pericycle; marked by a composite and continuous cylinder of sclerenchyma,
consisting of sclereids and of fibres with very thick walls and narrow lumina. Phloem;
somewhat collapsed in the dried material available for examination, but, when sufficiently well preserved, tending to be in the form of triangular strands with outwardly
directed apices. Ends of the rays, where traversing the phloem, broadening towards
the exterior of the stem, but this character more obvious in some specimens than in
others.
Xylem; in the form of a closed cylinder traversed by one- or two-seriate rays. Vessels
mostly solitary, c. 20-100 p in radial diameter but tending to be larger in the Stuart
specimen than in the three others (see Material examined) ; shape variable, ranging
from rounded to oval or elliptical and sometimes polygonal. Pits in lateral walls of
vessels rather widely spaced, mainly alternate but with a tendency to be opposite;
individual pits circular and bordered with horizontal, slit-shaped apertures. Vessel
perforations simple, somewhat oblique. Wood fibres with moderately wide lumina
and bordered pits. Pith; mostly composed of thin-walled parenchyma with small
intercellular spaces in angles between the cells; peripheral part of pith composed
of three or four layers of much smaller, collenchymatous cells.
CONCLUSIONS
I n drawing taxonomic conclusions in the light of these observations it must be
clearly understood that our knowledge of the structure of the vegetative organs of
the families that have been suggested as possible relatives of Emblingia is very imperfect. T h e slides of Emblingia have, however, been compared with the descriptions of
Capparaceae, Goodeniaceae, Polygalaceae and Sapindaceae given in Metcalfe and
Chalk’s Anatomy of the Dicotyledons. Comparisons have also been made with
microscope slides of representatives of these same four families filed in the reference
184
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C . R. METCALFE
collection at the Jodrell Laboratory at Kew. Some of these slides have been made
since Anatomy of the Dicotyledons was written, and indeed a number of entirely
new ones, especially of Goodeniaceae and Polygalaceae, were specially prepared for the
purpose of this investigation.
These comparisons, in the writer’s opinion, indicate that the histological characters
of Emblingia are much more like those of the Goodeniaceae than those of the other
three families. T h e next closest resemblance is to Polygalaceae with Capparaceae and
Sapindaceae falling a long way behind. One of the difficulties is that it is possible to
find at least a few characters in which Emblingia resembles certain representatives of
all the families under consideration. Although these are characters of which use is
commonly made for taxonomic purposes, they are, by themselves, of restricted
significance because they occur in many families between which it is quite clear on
general grounds that there can be no close affinities. Characters such as anomocytic
stomata and the possession of vessels with simple perforations are of very restricted
significance in the problem before us because they both occur so widely amongst
dicotyledons. We must, therefore, be on our guard not to treat these characters as if
they are of equal importance to all of the other points of similarity or distinction. If
we merely add up the number of characters that appear to be in favour of or against
a particular taxonomic affinity, without taking the relative significance of these characters into consideration, we may easily reach a wrong conclusion.
Bearing this in mind we may now go on to note that characters in which Emblingia
resembles the Goodeniaceae include the following. (i) Leaf characters. Unicellular
hairs which are minutely warty when viewed in aqueous mounts. (Amongst the
Goodeniaceae these have been seen only in certain species of Scaevola.) Anomocytic
stomata. T h e occurrence of numerous, profusely but shortly branched sclereids in
the mesophyll and to a lesser extent in the stem cortex. (Branched sclereids are much
less numerous in Gardner 9388 than in the other material of Emblingia examined,)
Vascular bundles of the leaf sheathed by inflated parenchymatous cells rather than
by sclerenchyma. (ii) Stem characters. Deep seated origin of the cork. Xylem in the
form of a closed cylinder traversed by narrow rays, the rays themselves being composed mainly if not entirely of tall upright cells. T h e mostly solitary vessels of which
the diameters are of the same order of length. Simple perforations to the vessels.
Wood fibres with bordered pits. Well developed pith.
T h e characters just listed all occur in members of the Goodeniaceae, but it must
not be imagined that all of the characters are to be found in every species. Nevertheless
it must be agreed that this list of characters that occur in Emblingia as well as in certain
members of the Goodeniaceae is quite substantial.
It must be conceded that a number of these same characters is also common to
Emblingia and certain representatives of the Polygalaceae. For example, branched
sclereids occur in the mesophyll of Moutabea guyanensis as well as in Emblingia, but
the sclereids in Emblingia are much more branched and do not extend from one leaf
surface to the other as they do in Moutabea. Another interesting point of resemblance
is the occurrence of minutely warty hairs in Emblingia and in certain species of
Securidaca and Polygala. Against this it may be noted that if Emblingia twigs are
compared with twigs of about the same diameter belonging to members of the Poly-
RELATIONSHIPS
OF EMBLINGIA
185
galaceae represented in the Kew slide collection one cannot fail to be impressed by
the fact that the vessels of the Polygalaceae are not only wider in diameter than those
of Emblingia and of the Goodeniaceae but they are much more widely spaced. Furthermore in the Polygalaceae the wood parenchyma often tends to be aliform whereas
this is not so in Emblingia. I t was, however, noted that in their size and distribution
the vessels of certain specimens of Emblingia are not unlike those of certain species of
Polygala .
If we now compare Emblingia with Sapindaceae we can see that Emblingia differs
in the following respects. I n the Sapindaceae the xylem usually has vessels in multiples,
whilst the wood fibres have simple pits and are often septate. Turning to the leaf, the
vascular structure of the petiole in the Sapindaceae, in transverse sections through the
distal end, is in the form of a cylinder rather than an arc, and in many members of the
family the vascular structure of the petiole is still more complex owing to the occurrence of medullary bundles. Secretory cells, which are a very characteristic feature of
the leaf of the Sapindaceae, have not been seen in Emblingia. It may be noted that
minutely warty, unicellular hairs similar to those of Emblingia have been seen in
Diplopeltis huegellii Endl. (Cottesloe, W. Australia, A. Morrison 10023) of the Sapindaceae, but this character on its own does not appear to be of much significance in
view of the many notable differences between Emblingia and members of the Sapindaceae.
There is scarcely any need to draw a detailed comparison between Emblingia and
Capparaceae since it can readily be seen that the characters for Capparaceae as
recorded in Anatomy of the Dicotyledons do not agree very well with those of
Emblingia.
T o recapitulate and summarize, it is clearly evident that the anatomical comparisons
that have been made go to show that the closest agreement that has been detected is
between Emblingia and Goodeniaceae, and that some resemblances but also some
important differences between Emblingia and the Polygalaceae have been noted.
The resemblances between Emblingia on the one hand and Capparaceae and Sapindaceae on the other appear to be too few to have any taxonomic significance. I n
dealing with problems of this kind, however, it would be wise to treat our conclusions
as provisional until our picture of the anatomy of the dicotyledons as a whole is more
complete. It is at present far less complete than is generally recognized and this shows
how urgent it is to press on with the study of systematic anatomy.
ACKNOWLEDGEMENT
The authors would like to thank Miss M. Gregory for preparing a combined abstract
of the four contributions and reading proofs of the joint paper.
REFERENCES
CAROLIN,
R. C., 1959. Floral structure and anatomy in the family Goodeniaceae Dumort. Proc. Linn.
SOC.
N.S.W. 84: 242-255.
CAROLIN,
R. C., 1966. Seeds and fruit of the Goodeniaceae. Proc. Linn. SOC.N.S.W. 91: 58-83.
DAVIS,G. L., 1966. Systematic embryology of the Angiosperms. New York: John Wiley.
ERDTMAN,
G., 1954. Pollen morphology and plant taxonomy. Bot. Notiser, 1954: 65-81.
186
G. ERDTMAN,
P. LEINS,R. MELVILLE
AND C. R. METCALFE
LARSON,
D. A. & SKVARLA,
J. J., 1961. The morphology and fine structure of pollen of Polygala alba
Nutt. and P . incarnata L. Pollen et Spores, 3 : 21-32.
LEINFELLNER,
W., 19.58. u b e r die peltaten Kronblatter der Sapindaceen. &err. bot. Z . 105: 443-514.
MELVILLE,
R., 1962. A new theory of the Angiosperm flower. 1. The gynoecium. Kew Bull. 16: 23.
MUELLER,
F., 1860-1. Fragmenta Phytographiae Australiae, 2 : 2-4. Melbourne.
L., 1896. Sapindaceae. In Engler, A. & Prantl, K., Die natiirlichen Pflanzenfamilien, 3 (5):
RADLKOFER,
277-366.
R O S ~ NW.,
, 1946. Further notes on the embryology of the Goodeniaceae. Acta Horti gothoburg. 16:
235-249.
EXPLANATION OF PLATE
PLATE
1
Emblingia calceolijlora. Pollen grains in equatorial (A-D) and polar (E) view (x 1000). A shows the
very short colpal part of one of the three compound apertures. It has rounded ends, in conformity
with the colpal parts of the apertures in some polygalaceous species (e.g. Polygala serpyllacea and
P . vulgaris; see P1. 4 5 : 3 in Erdtman, Berglund and Praglowski: A n introduction to a Scandinavian
pollen $om. Stockholm 1961, and P1. 57: 3 in the second volume of the same publication, Stockholm
1963). The membrane of the colpal part of the apertures is granulate. B and C exhibit the pronounced
exinous thickening bordering, like thick lips, the inner, oral part of the compound apertures. Cf. also
D (note pouting lateral parts) and E (corners).
l 3 o t . r . Linn. SOC.,62 (1969)
G. ERDTMAN, P. LEINS. K. MELVILLE
Plate 1
AND
C. R. METCALFE
(Facing p . 186)