Comercio vainlla

B Olmi~alJoumaldthc Linnean socicry (1999), 131: 353-382. With 36 figures
Article I :bojL1999.0271, available online at http://www.idealibraryxom on
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Comparative vegetative anatomy and
systematics of h d Z u (Orchidaceae)
WILLIAM LOUIS STERN FLS* AND WALTER S . JUDD
Depa*ent

ofBotmy, Universip o Florida, Gainaville, Florida 32611-8256, U.S.A.
f

Received Manh 1999;accqbtedfor publication June I999

V i d l a is a pantropical genus of green-stemmed vines bearing clasping (aerial) and absorbing
(terrestrial) roots. Most vanillas bear normal, thick foliage leaves; others produce fugacious
bracts. Seventeen species, including both types were studied. Foliage leaves of Vanilla a re
glabrous, have abaxial, tetracytic stomatal apparatuses, and a homogeneousmesophyll.
Species may or may not have a uniseriate hypodermis. Crystals occur in the foliar epidermises
of some species, but all species have crystalliferous idioblasts with raphides in the mesophyll.
Vascular bundles in leaves are collateral and occur in a single series alternating large and
small. Sclerenchyma may or may not be associated with the vascular bundles. Scale leaves
may becrescent or C-shaped and usually have abaxial stomatal apparatuses. A hypodermis
may or may not be present; the mesophyll contains raphide bundles in idioblasts. Vascular
bundles are collateral and occur in a single row sometimes aligned close to the adaxial
surface. They may or may not be associated with sclerenchyma. Stems of leafy vanillas show
a sclerenchyma band separating cortex from groundtissue; stems of leafless vanillas do not
show a sclerenchyma band. Ground tissue of the stem may consist solely of assimilatory cells
or mixed assimilatory and water-storage cells. In some species centrally located assimilatory
cells are surrounded by layers of water-storage cells. A uniseriate hypodermis is present in
all stems. Sclerenchyma may completely surround the scattered collateralvascular bundles,
occur only on the phloem side, or be absent. Both aerial and terrestrial roots a re notable
for their uniseriate velamen the cell walls of which may be unmarked or ornamented with
anticlinal strips. Exodermis is uniseriate; the cells vary from barely thickened to strongly
thickened. Only the outer and radial walls are thickened. Cortical cells of aerial roots generally
havechloroplasts that are lacking from the same tissue of terrestrial roots. Raphide bundles
occur in thin-walled cortical idioblasts. Endodermis and pericycle are uniseriate; pericycle cells
are all 0-thickened opposite the phloem. Cells of the endodermis are either 0 -or u-thickened
opposite the phloem. Vascular tissue may be embedded in t i -or thick-walled sclerenchyma
hn
or in parenchyma.Metaxylem cells are always wider in terrestrial than in aerial roots of the
same species. Pith cells are generally parenchymatous but sclerotic in a few species.
8 1999 The Linnean Society of London

ADDITIONAL, KEY W0RLlS:-

scale leaves - cauline sclerenchyma band

-

aerial roots

- terrestrial roots - velamen.
CONTENTS

Introduction . . . . . . . . . . . .
Works devoted exclusivelyto Vanilla .
Works not devoted exclusively to Vanilla
Material and methods . . . . . . .

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354
355
357
359

* Corresponding author. Email: wstern@botany.ufl.edu
0024-4074/99/120353+30 $30.00/0

353

Ca 1999 The Linnean Society of London

W. L. STERN AND W.S. JUDD

354

Results . . . .
Foliage leaves .
Scale leaves .Stems . . .
Roots . . .
Discussion . . .
Anatomy . .
Cladistics . .
Acknowledgements
References . . .

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