Annals of R.S.C.B., Vol. XX, Issue 3, 2016, pp. 12 - 16
Received 15 July 2015; accepted 11 August 2016.
doi: 10.ANN/RSCB-2016-0002:RSCB
Histoanatomical analysis of Begonia rex Puiz. leaf
RODICA BERCU, A. BAVARU, D. R. POPOVICIU
Faculty of Natural and Agricultural Sciences “Ovidius” University, Constanța, Romania
*Corresponding author
D. R. Popoviciu, Ph.D.
Faculty of Natural and Agricultural Sciences “Ovidius” University,
Campus, Aleea Universitǎţii, nr. 1, Corp B, 900 525, Constanţa, Romania
Phone: +40(0)761.178.785, e-mail: [email protected]
1
Keywords. Anatomy, petiole, lamina, stomata, Begonia rex.
Summary
pink, green, silver, red, purple and brown
spots on the upper surface of the lamina. In
some species, the leaves are velvety surfaced,
others are curved, some have soft edges,
others are crested (Web 1).
The paper presents anatomical aspects
concerning the leaf structure of two Begonia
× hiemalis Fotsch (Begonia Hiemalis Group)
varieties, belonging to Begoniaceae family:
Begonia elatior 'Britt Dark' and Begonia
elatior 'Clara'. Anatomically, the petiole has a
single-layered epidermis, the cortex and the
vascular system. The vascular system is a
fascicular type one, with a large number of
poorly developed collateral bundles, placed
into a basic tissue. The lamina is composed of
a single upper layer of cells for B. elatior
'Britt Dark', and a hypodermis for B. elatior
'Clara', a single-layered lower epidermis and
the
mesophyll.
The
mesophyll
is
differentiated into palisade tissue and spongy
tissue with the same vascular bundle structure
such as that of the petiole but with foliar
arrangement of conductive tissues. Glandular
hairs, druses and taniniferous cells occur in
the petiole and blade. Stomata are present on
the lower epidermis.
Fig. 1. Natural view of Begonia rex Puiz.
In literature, few data are known
concerning the leaf anatomy of Begonia
species, especially the petiole structure. The
most ample paper which analyzes, in
particular, the structure of the leaf upper
epidermis of 11 shade and shadow Begonia
species, originating in Central America is that
of Li JingXiu (2007). A large contribution to
the study of some Begonia species stem and
leaves belong to Barkley and Hozid (1971)
with special references to the multi-layered
epidermis. An ample study of the leaf and
stem hairs of a number of Begonia species
were studied by Boghdan and Barkley (1969).
Introduction
Begonia rex Putz. (Begoniaceae family) is a
rhizomatous Begonia species, native to the
tropics and subtropical regions of Africa, Asia
and America. It is a herbaceous decorative
indoor plant especially through the multitude
of combinations of colors and hues present on
the surface of leaves. On a single leaf, three or
four colors and so many shades can be
distinguished. The leaves have cordate
asymmetric, slightly crenate margins, with
The Romanian Society for Cell Biology ©, Annals of R. S. C. B., Vol. XX, Issue 3, 2016, D. R. Popoviciu, pp. 12 – 16
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Annals of R.S.C.B., Vol. XX, Issue 3, 2016, pp. 12 - 16
Received 15 July 2015; accepted 11 August 2016.
doi: 10.ANN/RSCB-2016-0002:RSCB
Succint reference of begonias leaves,
especially concerning the photosensitive cells
of epidermal cells, are found in Vogelmann
and Brodersen (2007), Sandved (1969),
Vogelmann et al. (1996) and Wagner et al.
(2003) studies.
In Romania few authors have studied
begonias from a morphological, physiological
(Romocea et al., 2010; Romocea, 2011) and
anatomical (Bercu & Jianu, 2004, Bercu,
2005) point of view.
The aim of this work is to analyze the
anatomy of the petiole and lamina of Begonia
rex, bringing additional knowledge about this
group of plants, in general and, in particular,
for this species.
A
Materials and methods
The plant leaves were collected form S.C. Iris
International S.R.L. greenhouse. Small pieces
of root, stem and leaves were fixed in FAA
(formalin: glacial acetic acid: alcohol 5:5:90).
Cross sections of the vegetative organs were
performed by freehand technique (Bercu &
Jianu, 2003). The cross section samples were
stained with alum carmine and iodine green.
Histological observations and micrographs
were performed with a BIOROM–T bright
field microscope, equipped with a TOPICA
6001A digital camera attachment. equipped
with a TOPICA 6001A digital camera
attachment.
B
Fig. 2. Cross section of the petiole - ensemble (A- x
80; B- x 60): bt- basic tissue, c- cortex, e-epidermis,
gh- glandular hair, ngl- non-glandular hair, vb vascular bundle.
Results and discussions
The petiole in cross section is circular in
shape (Fig. 2). The epidermis has a single
layer of cells covered by a thick cuticle. Here
and there some long, simple protective, nonglandular hairs (40-50 cells) and as well rare
peltate (8 cells) glandular hairs are present
(Fig. 2, A, B).
The Romanian Society for Cell Biology ©, Annals of R. S. C. B., Vol. XX, Issue 3, 2016, D. R. Popoviciu, pp. 12 – 16
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Annals of R.S.C.B., Vol. XX, Issue 3, 2016, pp. 12 - 16
Received 15 July 2015; accepted 11 August 2016.
doi: 10.ANN/RSCB-2016-0002:RSCB
A
A
B
Fig. 3. Cross section of the petiole – details. Portion
with epidermis and cortex (A, x 150). A petiolar
vascular bundle of the (B, x 300): co- collenchyma, eepidermis, gh- glandular hair, ic- inner cortex, phphloem, ngh- non-glandular hair, x- xylem.
B
Fig. 4. Cross sections of the lamina. Portion with
mesophill and mid-rib (A, x 70). Portion with
mesophyll (B, x 350): co- collenchyma, h- hipodermis,
le- lower epidermis, ms- mesophyll, pt- palisade tissue,
The Romanian Society for Cell Biology ©, Annals of R. S. C. B., Vol. XX, Issue 3, 2016, D. R. Popoviciu, pp. 12 – 16
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Annals of R.S.C.B., Vol. XX, Issue 3, 2016, pp. 12 - 16
Received 15 July 2015; accepted 11 August 2016.
doi: 10.ANN/RSCB-2016-0002:RSCB
s- stoma, st- spongy tissue, ue- upper epidermis, vbvascular bundle.
epidermis and the xylem tissue near the pith
zone. Phloem tisses is composed of phloem
vessels, companion cells and phloem
parenchyma. whereas the xylem one of xylem
vessels and xylem parenchyma. The vascular
bundles are surrounded by a bundle sheath
(Fig. 3, B).
The central zone is made up of large thinwalled cells with intercellular spaces (Fig. 2).
Cross sections of lamina disclose an upper
epidermis made up by a layer of slightly
tangent elongated cells, without spaces
between cells, covered by a thick cuticle.
Between the upper epidermal cells,
photosensitive
papillae,
which
are
characteristic to shadow Begonias (Brodersen
& Vogelmann, 2007; Vogelmann et al.,
1996), have not been observed in our
findings.
The same non-glandular and glandular
hairs of the petiole, are mostly present in the
mid rib zone. A three-layered hypodermis
follows, composed of large, radiallyelongated cells.
The mesophyll is poorly developed,
differentiated into palisade and spongy tissue
(heterogenous mesophyll). The palisade tissue
is composed of a small number of cell layers
(2 layers), while the more developed spongy
tissue has 4-5 layers of cells (Fig. 4, A, B).
However, Li JingXiu et al. (2007) research
showed, as an ecological adaptation, that
species of Begonias in areas with low light
and humidity, have thinner mesophyll with
poorly developed palisade tissue (the
rhizomatous Begonias with erect stems) than
those living in full sun and xerofitic
environment. The mid rib is more prominent
on the lower epidermis than on the upper one
(Fig. 4, A). The vascular system of the mid
rib is composed of four vascular bundles, a
larger one in the center and three smaller
towards the upper epidermis. The vascular
bundles have the same structure to those of
the petiole but with typical foliar conductive
tissues arrangement. Stomata are present only
on the lower epidermis (hypostomatic
lamina).
The lower epidermis cells, in paradermal
sections, discloses hexagonal cells with
straight walls and anisocytic type stomata,
more specifically, amphianisocytic with two
A
B
Fig. 5. Paradermal sections of the lower epidermis.
Ensemble (A, x 200). Detail (B, x 520): ec- epidermal
cell, sc- subsidiary cell, s- stoma cell.
It is followed by the cortex, differentiated
into an external (hypodermis) and an inner
one. The external cortex is represented by an
angular collenchyma, 3-4 layers of cells, and
the inner one is more developed, composed of
3-5 layers of parenchymatous cells (Fig, 3,
A).
Such as in other Begonia species leaves
petiole, the vascular system, embedded into a
basic tissue, is of fascicular type (Barkley,
1971; Bercu, 2005), composed of a large
number of collateral vascular bundles
(Barkley, 1971; Bercu, 2005). In Begonia rex
the petiole has 14 vascular bundles arranged
on two circles (7 on the inner circle and 7 on
the external one) (Fig. 2, A, B). Each vascular
bundle has the phloem tissue next to the
The Romanian Society for Cell Biology ©, Annals of R. S. C. B., Vol. XX, Issue 3, 2016, D. R. Popoviciu, pp. 12 – 16
15
Annals of R.S.C.B., Vol. XX, Issue 3, 2016, pp. 12 - 16
Received 15 July 2015; accepted 11 August 2016.
doi: 10.ANN/RSCB-2016-0002:RSCB
Begonia L. (Begoniaceae) species, Analele
Universităţii „Ovidius”, Ser.: Biologie-Ecologie, 9:
3-7, „Ovidius” University Press, Constanţa.
Boghdan, K.S., Barkley, F.A., 1969, Begonia
trichomes, The Begonian, 36: 130-132, Los
Angeles.
Brodersen, C.R., Vogelmann, T.C., 2007, Do
epidermal lens cells facilitate the absorptance of
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Louis.
Dilcher, D.L. 1974, Approaches to the identification of
angiosperms leaf remains, Bot. Rev., 40(1): 91-103.
Givulescu, R., 1999, Flora mică ilustrată a terţiarului
din România, Casa Carții de Ştiință, Cluj-Napoca.
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2007, Anatomy on leaf cross sections of Begonia
from Yunnan, China, Guangxi Zhiwu/Guihaia,
27(4): 543-550.
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Cour. Forsch. Inst. Senckenberg, 30: 265-171,
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Vogelmann, T.C., Bornman, J.F., Yates, D.J,. 1996,
Focusing of light by leaf epidermal cells, Physiol.
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Web
1
http://www.plantemania.ro/plantedecorative/plante-de-interior-2/begonia-rex/
circular rows of subsidiary cells. The inner
circle possesses two subsidiary large cells and
a small one, whereas the external one is
incomplete, with two subsidiary cells.
Remarkable are the rare twin stomata (Fig. 5,
A, B).
The lower epidermis possesses relatively
few small stomata 29.65 st./mm2 with 0.181
stomatal index (IS) (Dilcher, 1974, Monton,
1976).
Conclusions
The petiole has a single-layered epidermis
and a differentiated cortex.
The vascular system is fascicular,
composed of a large number of collateral
vascular bundles, arranged on two circles,
embbedded in a basic tissue.
The lamina has an single-layered upper
and lower epidermis and hypodermis, as well.
The mesophyll is poorly developed,
heterogenous and hypostomatic. The vascular
system of the mid rib is represented by four
vascular bundles with foliar arrangement of
the conductive tissues. The strength of the
petiole and lamina is due to the collenchyma
tissue.
The lower epidermis, in paradermal
sections, disclose hexagonal cells with
straight walls and anisocytic type stomata. It
has relatively few stomata 29.65 st./mm2 with
0.181 stomatal index.
Acknowledgements
We express our thanks to dr. ing. Elena
Bavaru manager of S.C. “Iris International”
S.R.L., Constanța, for the plant material
supplied for this study.
References
Barkley, F.A., Hozid, B., 1871, Leaf anatomy of
Begonia, The Begonian, 38(6): 135-142, Los
Angeles.
Bercu, R., Jianu, D. L., 2003, Practicum de morfologia
si anatomia plantelor, „Ovidius” University Press,
Constanța.
Bercu R., 2005, On the leaf histoanatomy of some
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