The external surface of the valves is generally convex> I 
and marked with a longitudinal furrow; but there 
are cases in which it is transverse, as in Anagallis . 
[See Pericarp .] 
Vascular Organs.- — In the analysis of vegetable fabric, the 
organs of which the plant are composed are found 
to be reducible either to epidermoid laminae, or to 
cells or to longitudinal fibres. The two former wehave 
already described under the heads of the Epidermis 
and the Cellular Tissue. We now proceed to the 
latter. Are the fibres of plants tubular? 
If the. stem of a plant of Marigold is divided by means 
of a transverse section, the divided extremities of the 
longitudinal fibres arranged in a circular row, immedi- 
ately within the bark, will be distinctly seen, and their 
tubular structure demonstrated, by means of the 
orifices which they present, particularly when the stem 
has begun to wither. The tubular structure of woody 
plants is not so easily demonstrated. We might infer 
it however from the force and facility with which the 
sap ascends to the very summit of the stem in the 
spring and summer, and there are some cases in which 
we may discern it, even with the naked eye. On the 
horizontal section of a piece of wood that has been 
long exposed to the action of the atmosphere, the 
orifices of the longitudinal tubes will appear arranged 
in circular rows, in the direction of the concentric 
layers. Further, Hedwig affirms that he observed 
them on the transverse section of a branch of the Pear- 
tree detached even in the spring, when the sap was 
flowing. \_De Fib. Veg. Oct. sect. 1.] 
Hence we believe that the longitudinal fibres of plants 
are in fact longitudinal tubes, conveying the alimen- 
tary juices. They exhibit a considerable variety of 
structure, and have been distributed by botanists into 
several distinct species. 
Vault. — The Vault is a process issuing from the upper 
extremity of the tube of a Monopetaious corolla; 
Linnaeus regarded it as a nectary 
Veil. — The Veil or curtain is a fine and delicate membrane 
that unites the circumference of the Pileus to the 
circumference of the stem of the Fungi, and protects 
the Gills. 
Veins. — The ramifications of the Petiole, as dispersed through- 
out the expansion of the leaf are very generally called 
Veins ; and under certain modifications they are also 
called nerves. 
Vernation. — The leafing of plants is, in the language of 
Linnaeus their vernation or foliation. 
Vesicul/e. — T he little air bags or bladders that serve to float 
the leaves of the Fuci and various other plants are 
designated by the appellation of Vesiculae. 
Villous. — Parts covered with long soft hairs. 
Viscid. — Parts covered with a clammy juice. 
V itellus. — The Vitellus is a peculiar organ proper to the seeds 
of certain orders of plants. In Grasses it occurs in the 
form of a small scale interposed between the albumen 
and embryo, but it takes no development in germi- 
nation. 
Volva. — The Volva or wrapper, is a sort of radical and mem- 
branous integument peculiar to certain species of 
Agarics, which envelopes them entirely in the early 
stage of their growth, and then bursts open and 
unfolds the plants. 
Wedge-shaped. — Cuneiform, broad at the base, and tapering 
towards the point. 
Wheel-shaped. — Rotate or Wheel-shaped, when the corolla 
spreads without any tube, as in Dulcamara. 
Whorl. — The Whorl is a mode of flowering in which the 
flowers are placed around the stem or branch as a 
common axis, in the form of a ring. The Verticillate 
flowers of Tournefort, or Labiate flowers of Linnaeus 
afford the best examples. The Whorl is said to be 
sessile or pedicled, according as the individual flowers 
composing it are sessile or pedicled. In some plants 
the Whorls stand close to one another, in others they 
stand wide apart; in some they are naked, that is 
without leaves ; in others they are interspersed with 
small leaves or bractes, as in Ajuga reptans. 
Wing. — The two side petals of papilionaceous flowers are deno- 
minated the wings; and the membranaceous append- 
age that issues from the side or apex of some seeds, 
as that of Syringa, is also denominated the wing. 
Winged-leaf. — The winged-leaf is a species of compotmd 
leaf, having leaflets or distinct expansion arranged on 
opposite sides of the petiole, as in the Pea and Vetch. 
If the insertions of the leafits are opposite, the leaf is 
said to be oppositely winged ; and if they are alter- 
nate, the leaf is said to be alternately winged. If the 
petiole supports an odd leafit at the extremity, the 
leaf is said to be unequally winged ; if it does not sup- 
port an odd leafit, then the leaf is said to be abruptly 
winged. 
Wood. — In trees or shrubs the body of the caudex, whether 
ascending or descending, consists chiefly of a firm and 
compact substance, called wood ; the central portion 
or pith, and the external portion or bark, being but 
small in comparison. The horizontal section of an 
Oak-tree or of an Ash will demonstrate this distinctly. 
