958 
Two species, the perfoliate and the stem-clasp- 
ing, both about 4 feet high and blooming in July 
and August, have been introduced to British 
gardens ; and they love a soil of peaty loam, and 
are propagated from cuttings. The name vascoa 
was given in honour of the celebrated navigator 
Vasco de Gama. 
VASCULARES. One of the two grand or 
primary divisions of the vegetable kingdom. It 
is very nearly identical with the Phenogamia 
of Linnzeus and the Cotyledonez of Jussieu ; but 
is preferred to these by later botanists on ac- 
count of its expressing a more important and 
more extensively constitutional character. The 
same plants, when viewed as phenogamous, have 
true or obvious flowers,—when viewed as coty- 
ledonous, have true or lobed seeds,—and when 
viewed as vascular, have not only cellular tissue, 
but a system of tubular and spiral vessels. 
Though the characters of flower and seed are suf- 
ficiently distinct for every purpose of mere clas- 
sification, yet they exist only in very small parts 
of a plant, and in parts not present during the 
greater portion of the year, and are in some in- 
stances far too obscure and minute to serve as 
indications to a merely popular observer; but 
the character of vascularity pervades the whole 
structure, and remains patent to observation at 
all seasons of the year and in all conditions of 
the plant; and developes broad exterior distinc- 
tions which are readily recognised by the most 
unpractised eye. Many vascular plants, in par- 
ticular, declare themselves to every peasant by 
the existence of woody fibre; and both these 
and all the others proclaim themselves in the 
veinedness of their leaves. See the articles Cuz- 
LULARES and Borany. 
One set of vessels in vascular plants are sim- 
ple tubes called lymphatics by Decandolle, false 
trachez by Mirbel, and corpus culiferous or glo- 
bule-bearing tubes by Dutrochet. They have no 
valves and no lateral intercommunication; they 
abound in both the hard wood and the soft wood 
of ligneous exogens, particularly between the 
concentric layers of different years, but do not 
occur in either the pith or the bark; they are 
studded with small globules or molecules, which 
lie embedded in their walls; and they serve as 
the channels of the ascending sap, and may 
readily be seen to pour out from the orifices of 
their section the bleeding juice of a cut vine.— 
Another set of vessels are short, oblong, spindle- 
shaped tubes, swollen in the middle, pointed at 
the extremities, and often divided by transverse 
plates. They consist of very firm membrane, 
but have no globules; they are arranged in 
longitudinal series along the alburnum and the 
bark, down to the interior of the root; those of 
adjoining series touch one another at the mid- 
dle, but have spaces for other vessels between 
their intrinsically contracting and mutually re- 
ceding extremities; and all have lateral commu- 
nications and a porous wall, and serve to conduct 
VASCULARES. 
the cambium or elaborated juice from the leaves 
of all the plant’s exterior downward and retro- 
gradingly through all its spray and branches and 
stem and root.—A third set of vessels are spiral 
tubes or trachez,—fine, filmy, and transparent, 
twisted in the form of a corkscrew, either from 
right to left, or from left to right,—occasionally 
interspersed with the other sets of vessels, but 
easily distinguishable from them by their spiral 
form and their filminess,—terminating each in 
a sort of conical and spiry point,—and furnished 
with nervous globules similar to those of the 
cells. The functions and even the structure of 
these vessels have been a subject of great debate 
and of wide diversity of opinion among phytolo- 
gists; and we shall therefore, in the following 
paragraph, quote a somewhat extended account 
of them from Keith.—A fourth set of vessels are 
tubes of similar form and character to the lym- 
phatics, but comparatively very wide in diameter, 
destitute of globules, and serving to convey the 
descending and secreted fluids peculiar to each 
species of plant, such as the yellow juice of the 
celandine and the milky secretion of the spurges, 
and therefore called proper vessels. They occur 
in both ligneous and herbaceous plants; and 
occupy comparatively large space in some of the 
most succulent and lactiferous and mucilaginous 
species.—A fifth set of vessels are articulated 
cellular tubes, or series of cells so concatenated as 
to be aggregately tubular, furnished with glo- 
bules and free from pores,—some of them ra- 
diating from the centre of the stem to the cir- 
cumference of the alburnum, and constituting 
what are popularly termed the medullary rays of 
trees and shrubs,—and others extending longi- 
tudinally through the plant, within the bark, at 
right angles to the radiating ones. The office 
of these vessels is fully more obscure than even 
that of the spiral vessels ; and probably is depen- 
dent on the office of the pith ; and possibly also 
has connexion with the function of a supposed 
sixth set of vessels, of very filmy texture, of an- 
astomising power, and of retiform distribution 
through all parts of the plant, from the root to 
the leaves and from the centre to the circumfer- 
ence,—a set of vessels, however, whose very ex- 
istence, to say nothing of their offices, is yet 
matter for enquiry. 
“Grew and Malpighi, who first discovered and 
described the spiral vessels,” says Keith, “re- 
presented them as resembling in their appear- 
ance the trachee of insects, and designated them 
by that name,—an appellation by which they 
are still very generally known. They do not oc- 
cur often in the root, or, at least, they are not 
easily detected in it, though Kieser is said to 
have found them in it, in great abundance. 
Dutrochet could find none, and denies their 
existence in the root expressly. For myself, I 
can safely affirm that I have repeatedly met with 
them in the root of the lettuce called cos lettuce, 
though not in any other root that I have ever 
