by Jussieu to designate one of his orders. It seems to 
be equal in extent to the Verticillatse of Linnaeus — 
flowers in a whirl with two gaping lips. 
Lacineated. — When cut into numerous irregular divisions, 
which are termed segments. 
Lanate. — When a part is covered with soft hairs, and has a 
woolly aspect. 
Lanceolate. — Lance-shaped. — Of a narrow oblong form, ta- 
pering towards the end. 
Latex. — The latex, according to M. Schultz, to whom we are 
indebted for the introduction of the term, is the pro- 
per juice or vital fluid of the plant, secreted from the 
crude sap in the inter-cellular passages, and is thus, in 
its formation, analogous to the formation of blood in 
animals. It is contained in delicate transparent membra- 
nous tubes, inter-communicating by lateral branches, 
and occurring both in the woody fibre and bark, which 
they ascend till they reach the leaves, whence they 
again descend till they reach the extremities of the 
root. The contained fluid is said to exhibit evidence of 
its being in motion, in distinct, but partial and irre- 
gular currents, some up, some down, some to the 
right, and some to the left, suddenly stopping, and 
then suddenly re-commencing, but not exhibiting any 
very close analogy to the circulation of the blood of 
animals. Lardner’s Cab. Cyclop. Fol. XXV. After 
all, the Latex of Schultz seems to us to be nothing 
more than the Cambium of Duhamel, under a new 
name, and it is well known that the anastomosing of 
vessels conducting fluids is not a new doctrine. — 
Look at them in the leaf. 
Leaf. — The Leaf, which belongs to the division of the tem- 
porary parts of the plants, is a thin and flat substance, 
of a green colour, issuing generally from the ex- 
tremity of the branches, but sometimes also immedi- 
ately from the stem or root, and distinguishable by 
the sight or touch into an upper and under surface, 
a base and an apex, with a mid-rib and lateral nerves. 
Yet leaves are not always thin and flat, nor are they 
always green. The leaves of the Aloe are thick and 
fleshy ; and the leaves of the several species of Beet- 
root are of a deep and dull purple. Neither are they 
always furnished with transverse or lateral nerves. 
Such are proper to dicotyledonous plants only, for in 
monocotyledonous plants, the nerves are all parallel. 
The point by which the leaf is attached to the plant is 
the base ; the opposite and terminating point is the 
apex ; the intermediate body of the leaf is the expan- 
sion ; and the boundary of the leaf is the margin. 
Lignin. — If a piece of the stem of a herb, shrub, or tree, is taken 
and well dried and afterwards digested, first in water, 
and then in alcohol, or such other solvents as shall pro- 
duce no violent effect upon the solid paits, and if the 
digestion is continued till the liquid is no longer co- 
loured, and dissolves no more of the substance of the 
plant, there will remain behind a sort of skeleton which 
constitutes the basis of the vegetable structure, and 
amounts to about 96 or 98 per cent., of the weight of 
the different kinds of wood. It has been by some 
chemists denominated Woody Fibre [Thomson,] and by 
others Ligneux [Raspaili] We believe there is now a 
leaning towards the use of the term Lignin, which we 
consequently adopt, though it is plain that it differs 
from wood or herb only in the want of such ingredients 
as have been abstracted by digestion. According to 
Raspail it is composed of cells, tubes, and spirals yet 
visible. The cells, which have been organs of elabo- 
ration, abound in the younger parts and in the pith. 
In the epidermis they are much flattened, in the pu- 
bescence they are much elongated. The tubes, which 
have been organs conducting the sapor juices, abound 
in the woody parts, forming layers of a sort of net- work, 
or insulated bundles. The spirals, whose office has 
been that of conducting air, abound in all phaenoga- 
mous plants, but especially in the leaves. [Noav. Syst. 
de Chim. 79.] When Lignin is distilled in a retort, it 
yields an empyreumatic oil, carburetted hydrogen gas, 
carbonic acid gas, and, according to Fourcroy, a por- 
tion of ammonia, indicating the presence of azote, as 
constituting one of its elements. [ Thomson's Chem .\ ] 
By the analysis of Gay Lussac and Tlienard, lOOparts 
of Lignin contain of carbon 52, and of oxygen and 
hydrogen, in the ratio which forms water, 48. Thus 
it is reducible to precisely the same elements as wood. 
Linear. — Of equal breadth, from the base of the apex. 
Lingulate, — Tougue-shaped. Of a thick oblong blunt figure, 
in the shape of a tongue. 
Legume. — The legume is a dry, and elongated pericarp or fruit, 
consisting of two valves with two opposite seams, to 
the one of which the seeds are attached, as in the pea 
or bean. It consists for the most part of one cell only ; 
sometimes of two, as in Astragalus; and sometimes 
of many, as in Lotus. It is one-seeded, or two-seeded, 
or many-seeded, as in Pisum. Its figure is oblong, 
as in Ulex ; or cylindrical, as in Orobus ; or rhom- 
boidal, as in Ononis. Its substance is membranaceous, 
as in Medicago; or leathery, as in Ficia ; and the sur- 
face smooth, as in Lathyrus Nessolia; or rough, as in 
Lathyrus hirsutus. 
Lepals. — The sterile stamens which occur in many flowers, 
originating in the same whirl, or between the true 
stamens and pistil, assuming the form of glands, or of 
petaloid scales, botanists designate by the term lepal. 
Liber. — The innermost layer of the bark is denominated the 
liber, the Latin name for a book, from the circum- 
stance of its having been sometimes used by the an- 
cients to write on, before the invention of paper. It is 
the finest and most delicate of all the layers of bark, 
and is often most beautifully reticulated. 
Lid. — When the calvptra of the mosses has fallen, the mouth of 
the capsule is still found to be covered with a lid, 
terminating in a beak or rostrum, usually called the 
operculum . 
Ligneous Lavers.— The ligneous layers are the concentric 
and annual layers, of which the woody parts of exoge- 
nous plants are composed ; soft at the circumference 
of the stem, but more solid at the centre. 
Limb. — The expanded border of a monopetalous corolla, or the 
upper and dilated part of an individual petal of a 
polypetalous corolla is usually designated by the ap- 
pellation of the limb — limbus, lamina. 
Lobe. — The larger portions into which some simple leaves are 
naturally divided are called lobes, and so also are the 
cotyledons of the seed. If the plant is monocotyledo- 
nous, the lobe is single; if the plant is dicotyledonous, 
the lobes are in pairs. 
Loculi. — The little cells of the anthers which contain the 
pollen are, in the language of botany, called Loculi. 
Loculicidal. — A mode of the dehiscence of fruits. 
Locusta. — The individual spikelet that makes part of the 
general spike of many of the grasses, as in Bromus, 
furnished at the base with a perianthium consisting of 
two opposite glumes, is by modern botanists denomi- 
nated a Locusta. 
Lomentum. — Besides the varieties of legume which we have 
already pointed out, there is a peculiar variety of it, 
which, though externally forming longitudinal sutures, 
to one of which only the seeds are attached, does not 
yet open longitudinally by means of twogeneral valves; 
but transversely, by means of joints, each joint forming 
a cell that contains one seed, which is finally extricated 
by the opening of the individual joint. This variety 
of legume was regarded by Wilidenow as containing a 
distinct species of pericarp, and designated by the name 
of the Lomentum ; but is a distinction to which it 
seems scarcely entitled. 
D 
