Comparative Anatomy of the Aerial Roots of Blue and Red Vandas and its Diagnostic Significance

2013·5.1 MB·English

by  Selvam, A B D

2013) ‘SELVAM : COMPARATIVE ANATOMY OF THE AERIAL ROOTS. 55

NELUMBO $5:55-61,2015 ISSN 0976 5068

COMPARATIVE ANATOMY OF THE AERIAL ROOTS
OF BLUE AND RED VANDAS AND ITS DIAGNOSTIC SIGNIFICANCE
‘ABD, Sava
Botanical Survey of nda, Pharmacognosy Seton
Howrah 711103,

ABSTRACT

‘The two highly endangered orchid species, Vanda coerulea Gri. x Lindl. (Blve Vands) and
-Renantheraimchootiana Rolfe (Red Vanda), could be easily identified whea thos rein lowering tats.
However, itis dificult ident them in their vegetative conditions since bo ofthe species resemble one
smother in apparent morphology. Inthe presen study, efforts have been made to identify them in their
‘vegetative conditions by the anatomical sirsctues of serial roots studied wader SEM (Sexnning Electron
Microscope) as wel as Light Microscope. The presence of modullary bundles in Red Vanda sms tobe a
unique diagnostic feature, which could be used identify the ud plant species ints vegetative condition.

INTRODUCTION

Orchids are important economic plans primarily for their omameatal se. Based o the oral colours, the
‘wo epiphytic species of Orchidaceae, Fada coerulea Gi x Lind. and Renantheraimschootana Rolfe, re
commonly refered to Blue Vands and Red Vanda respectively. Both of the species are native tothe Indo-
‘Burmese megs-bodivesity hotspot and they occurin high alituds inthe Nort-caster States of Indi andthe
joining areas of Western Myanmar (Nayar & Sasry, 1990; Kishor & Sharma, 2005), Those are very mich in
demand for heir beauiful armental flowers and ae highly priced all ove the world: Besides, the leaves and
flowers of Yanda coeruiea are used traiionaly in flk-medicine (Vij & Aggarwal, 2003). Fanda coerlea
flowers during September to February with October-November asthe peak flowering season, Sometimes, tbe
species lowers beyond its fweringscason in the month of June (Nayar & Sastry, 1990; Kishor & Sharma,
2003) Pato dar Bue Sowers ar relativey large an wih dak tesseliatins.Renantheraimschooiana isthe
only species ofthe genus Renanthera tat occurs in India The species lowers during April and May in Manipur
(Kishor & Sharma, 2005); May to July in Assam (Bose & a, 1999); September and October in Arunchal
Pradesh (Chowdhery 1998). The spectacular orange-red flowers are long lasting and thereby the species is
bighlyvaluedin borcltureas an ormamental. Both ofthe species arc highly endangered her natural babs.
anda cocrateaslistedin Appendix lofCITES. ln 1915, Renantheraimschootiana wasincludedin appendix
of CITES. Later oo, it was uplisted to Appendix Tin 1978. Endorsing the CITES decision, in 1998, the
‘Government o India has placod both the plant species in the Negative list of Export, which bans collection from
wildsourees(Chowhery, 1998; Kishor & Sharm, 208).

Yanda coerulea (Blve Vanda) and Renanthera imschootiana (Red Vand), could realy be identified
wn those arin ther flowering stats. However, tis dificulodatingush them in their vegetative conitons
since both he species esemble one snotherin appareat morphology.

The present sty involves anatomical studies ofthe acil roots ofthe species by SEM (Scanning
"leewon Microscope) as wllas Light Microscope to have a means of thes idatifction in vegetative states. I
say bementioned ta there isnoreportso fron the SEM sts of the aerial roto bese ax.

MATERIALS AND METHODS

‘The specimens of Yanda coerulea and Renanthera imschootana required for the present study were
collected from the Orcidarum of Botaial Suvey of adi of Shillong and Gangtok respectively, which were
‘dented by consulting Stat lors and also by comparing with the authentic specimens deposited in different
Indian herbaria viz. Central National Herbarium, Howrah (CAL), Botanical Survey of India, Easter Ciel,
Shillong (ASSAM) and Botanical Survey of Ind, Sikkim Himalayan Circle, Gangtok (BSH). The voucher

Da ofpbtewin 0 Deonbe, 2013 Rese 06482018 + Ase O1072013 ‘© Savy on 2013
56 NELUMBO vols

specimens were deposited inthe Crude Drug Museum (CDM) of Pharmacognosy Unit, Botanical Survey of
Indi, Howrah,

For Seanning Electron Microscopy, transverse sections of fresh or FAA-fixed acral root (without gold
coating) were directly mounted ona double-sided adhesive tape, which was alresdy fixed on ametallic specimen
stub, Later, the specimen stubs were placed over the Stage located in the specimen chamber of the Electron
Microscope and scanned at different magnifications under High Vacoum mode of « FETs Quanta 200
(Netherlands) Scanning Electron Microscope installed at Central National Herbarium, Botanical Survey of
Indi, Howrab,

‘To supplement the SEM studies, light microscopic studies ofthe anatomical features of the said orchid
species have also been carried out under an Olympus CX41 Microscope. In addition tothe visible light for
‘normal structural observations, polarized light was employed to observe critically the lignifod cells.
Photomicrographs were taken using an Olympus Digital Camera attachment (5.1 megapixels)
Photomicrographs ave been labeled using following abbreviations: Co-Cortex; En-Endodermis;
Ex-Exodermis; Fi-Fibres; Mvs-Medullary vascular strand; Pa-Parenchyma cells; Pe-Pericycle;
Pe-Phloem elements; PI-Pith; Rh-Rhizodermis; Sg-Starch grains, St-Stele; Vi-Velamen tissue;
Xe-Xylem elements

‘OBSERVATIONS

Vanda coerulea Grffex Lindl : The aerial r00t of coerulea shows the following structures under
‘SEM and light microscope. Rhizodermis is constituted ofa single row of radially elongated thin walled cells,
followed by 3 o 4 layers of velamen tissue comprising radially elongated, thin walled cells. Inner to the
velamen, there is a wider exodermal layer of radially elongated thin walled compact cells Inner to the
cexodermis is a wide cortex of homogencous parenchyma. Under light microscope, needle like calcium
‘oxalate crystals are seen in most of the cortical cells. Inner to the cortex isthe broad, circular stele at the
centre. The endodermis ismade up of layer a hick walled squatish cells with thin walled wide passage cells
at intervals of 7 to 10 thick walled cells. The pericycle has 2 layers of cells, the outer layer of thick walled
rectangular cells and the inner layer of thick walled polygonal. The vascular tissue consists of 15 exarch
xylem strands alternating with wide circular mastes of thin walled phloem clemeats. The cells surrounding
the xylem and phloem strands are smaller with thick lignified walls. Pith is wide and consists of angular,
compact, thick walled sclerenchyma cells, (L182)

Renanthera imschootiana Rolfe : The serial root of Renanthera imschootiana shows the following
structures under SEM and light microscope. Rhizodermis has a single layer of thin walled radially elongated
cells, The velamen consists of 2to 4 layers of radially elongated, thin walled and compact cells. The exodermis
consists ofa layer of aay elongated, thick walled cells. Inne othe exodermis isa relatively narrow zone of
cortex consisting of small, angular, thin walled compact parenchyma cells with needle like calcium oxalate
crystals. The stele is wider and cireular. The endodermis consists of layer of quarish thick walled cells with thin
walled passage calls at intervals of So 7 endodermal cells. The vascular issue consists of25 to 35 exarch xylem
strands alternating with radially stretched masses of thin walled phloem elements. The ground tissues
surrounding the xyiem and phloem strands are smaller with hick ignited wall. The central pith is offal thick
walled parenchyma cells. The pith parenchyma cellsare heavily loaded with starch grains L384)

‘CONCLUDING REMARKS

‘Acral roots of Blue Vanda and Red Vanda, in anatomical features, fundamentally resemble each other.
However, those can be distinguished readily by presence of starch grains inthe pith parenchyma cells of Red
‘Vanda and ther absence in the Blue Vanda and presence of3 prominent medullary vascular stands in Red Vanda
and absence of medullary vascular bundles in Blue Vanda. Those contrasting features enable he identification of
thetwo orchid species in their vegetative condition,
pvp of sal Fd conn tension view: Teen eco ofc ot
san (0), B. Veen tise and exodermis-se up View (2004. C. Asal fot showing Sbucte ofthe Se (250)
D.adodemis peryele snd acer clements-los pew 000).
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Plate 2: Light micracoic sien onthe srl roo of Vande coe: A. Tenens section of aril t= sce,
2 Reni Wes ann cnc ne pe Aaah care as DES,
'SELVAM : COMPARATIVE ANATOMY OF THE AERIAL ROOTS
60 NELUMBO vols

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Plate 4: Light microscopic ules onthe ai of Renamer muchootiaa: A Taste sc
sc B. Rizodrmls, Velanen tous, exademis and cortex clarged view; CSrae ofthe sel showing re
‘scularstands an pt. Annan view fama vascular stud saroundedby rea prechya cel
2013) ‘SELVAM : COMPARATIVE ANATOMY OF THE AERIAL ROOTS 6

ACKNOWLEDGEMENTS
‘The author is thankful to Dr. Paramyit Singh, Directo, Botanical Survey of India, Kolkata for providing
facilities and his constant encouragement. He is also grateful to Prof. P. Jayaraman, Director, Plant Anatomy
Research Centre, Chennai forhis critical comments and valuable suggestions.
[REFERENCES
‘Bost, TK, SK. BHATTACIARUEE,P DAS ANDU.C. BASAK. 199, Orchids ofIndia, pp. 417. Naya Prokash Calcutta.

CCHoWoHEKY, H. J. 1998, Orchid flora of Arunachal Prodesh, pp. 626, 682685, Bishen Singh Mabendra Pal Singh
Desire.

JOWANSEN,D.A. 1940, Plant Microechnique, p. 523. Me Graw HllBook Co. New York
‘ission, R. AND GJ. SHARMA. 2005. Renantanda Kebsana Shija, The Orchid Revew (Royal Horticultural Soci).
Vol 113 (1266), 325-327

Lory, JonNN.A. 1976. Seanning Electron Microscope study of Gree plans, The C.V. Mosby Company. Sunt Louis
Ta2,

METCALF, CR. AND L, CHALK. 1957. Anatomy ofthe Dicotyeons- Leaves, stem and wood in relation to taxonomy with
notes on Ecanomic uses, Oxford University Press. London, Vl. x-xiv.

[NAYAR,ML.ANDA.RK. SasTRY 1987, Red databook on Indian plants, Vol I,pp.278 Botanical Survey offndia, Kolkata,

NAYAR, MP. ANDA.RK. SASTRY. 1990, Red data book on Indian plants, VoL. I, 202 & 203. Botanical Suvey of India.
Kolkat,

‘SASS IE, 1940. lements of Botanical Micoteshniqus, pp, 222. Me raw Hill Book Co, New York

‘TROUGHTOM, JH. AND FB. SAMPSON. 1973, Plans: A Scanning Electron Microscope Survey, John Wiley & Sons
‘Australasia Pty Lid Sydey.

‘Vu,SP.ANDS. AGGARWAL. 2003. Regenerative competence of foliar expluns: Vanda coerulea Gif! reid Soe. India.
19012) 7-18.

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