ensue from the depredation of insects, nestling in the 
radicle, and consuming the nutriment of the plant, 
and thus debilitating the vessels of the leaf, so as to 
render them insusceptible to the action of light; or 
it may arise from poverty of soil. 
Excitability. — One of the most distinguishable properties of 
living vegetable structures, is that of their excitability, 
or capacity of being acted upon by the application of 
natural stimuli impelling them to the exertion of 
their vegetative powers ; the natural stimuli thus 
impelling them being light and heat. 
Excentric. — The embryo is said to be excentric when it is 
enclosed within the albumen, but not in the centre of 
it, as in asparagus. 
Exogenous. — Plants whose growth is affected by increments 
added to the circumference, are said to be exogenous. 
They are all dicotyledonous. But what are we to say 
of the growth of the primary shoot of the dicotyledo- 
nous seedling, or of the annual shoot of the fully 
developed plant ? and to what previous circumference 
does it add a new layer? This subject requires to be 
further investigated. 
External Structure. — The external structure of vegetables 
is that part of their fabric which is discoverable by 
outward inspection, as the root, stem, bud, branch, 
flower, and fruit ; all which organs form the ground 
of articles in their proper places. 
Exosmose. — A term introduced by M. Dutrochet, signifying 
a rush outwards, as applicable to the weaker impulse 
by which, through means of a current counter to that 
of endosmose and simultaneous with it, a more 
dense fluid passes through animal or vegetable mem- 
brane to a less dense fluid, and hence applicable to 
certain peculiar movements occuring in vegetable 
economy. 
Extract. — When vegetable substances are macerated in 
water, a considerable portion of them is dissolved; 
and if the water is again evaporated, the substance 
held in solution may be obtained in a separate state. 
This substance is denominated extract, though it 
must differ much in different plants. Vauquelin tried 
to reduce it to a single principle — the extractive; 
but as it was after all believed to be merely a mixture 
of various vegetable ingredients, it has ceased to be 
a leading object of chemical investigation. 
Face. — “That side of a seed which is most nearly parallel with 
the axis of a compound fruit, or the ventral suture 
or sutural line of a simple fruit, is called the face, 
and the opposite side the back.” Where the raphd 
is visible it indicates the face. Lind's. Introd. 181. 
Family. — A Family is an assembly of allied genera, whose 
structure and disposition of parts are founded on the 
same symmetrical plan, and whose external part or 
habit indicates their affinity ; the Mushroom, the 
Mosses, the Grasses, the Palms. 
Fascicle. — The Fascicle is a species of inflorescence similar 
to that of the corymb, but having its peduncles more 
crowded and condensed so as to form a sort of com- 
pact bundle. It is exemplified in Diantlius. 
Fasciculated. — When several leaves or flowers spring from 
the same point. 
Fecula — A term synonymous with starch. 
Fence.— The fence is the calyx orinvolucre of mosses — periches- 
tium — being an assemblage of loosely imbricated scales 
terminating in a fine hair or bristle, and surrounding 
the female flower. It is particularly conspicuous in 
the genus Hypnus. 
Fertile Flowers. — Flowers containing pistils only are said 
to be fertile, because they produce seeds, in contra- 
distinction to flowers containing stamens only, which 
are said to be barren, because they produce no seeds. 
Fibrous. — The fibrous or capillary root, consists of a number 
of small and thread-like fibres, one of which generally 
central, and the rest lateral. 
Filament. — The filament is that portion of the stamen which 
supports anther, and attaches it to the receptacle. Yet 
it is not always thread-shaped, as the name might lead 
us to suppose. In some species it is awl-shaped, in 
others it is club-shaped, and in others, as in Nympheea, 
it is petaloid, that is expanding like a petal. — Nor is 
it universally present, as forming essentially a part of 
the flower ; for some anthers are sessile, and conse- 
quently without filaments. The filaments are usually 
distinct, but they are sometimes united into one or 
more sets, and are hence said to be monadelphous, dia- 
delphnus, or polyadelphous. 
Filiform. — Thread-shaped; — Having a thread-like appearance. 
Floral Leaves. — A floral leaf is only another name for the 
Bracte. 
Florets. — The individual flowers of which a compound or 
aggregated flower is composed, are denominated florets 
or floscules. In the composite they are ligulate or 
tubular. The latter are the florets of the disk ; the 
former of the ray. 
Flower. — The flower, which, like the leaf, belongs to the divi- 
sion of the temporary parts of the plant, is a produc- 
tion that issues generally from the extremity of the 
branches, but sometimes also from the root, stem, and 
even leaf, being the apparatus destined by nature for 
the generation of the future fruit, and being distin- 
guished for the most part, by the brilliancy of its 
colouring, or sweetness of its smell. 
Flux of Juices. — When the sap ascends more copiously than 
it can be carried off, it often occasions a fissure of the 
solid parts, inducing disease or deformity, by encoura- 
ging the extravasation and corruption of the contained 
fluid, or a morbid flux of juices. The fissure is some- 
times occasioned by frost, forming what is called adouble 
alburnum ; that is, first, a layer that has been injured 
by the frost, and then a layer that passes into wood . 
But a cleft thus occasioned often degenerates into a 
chilblain that discharges a blackish and acrid fluid, to 
the great detriment of the plant, particularly if it is so 
situated that rain or snow will readily lodge in it. The 
sooner a remedy is applied to it the better, for it will 
not heal itself; and the only remedy yet known is the 
excision of the part affected, and the application of a 
coat of grafting wax. Wildenow, 353, Eng. Trans. 
Foliation. — The peculiar mode in which the incipient leaves 
are folded up within the leaf-bud is designated by the 
term foliation or vernation. 
Folioles. — Folioles, a diminutive from folium, a leaf, is a term 
sometimes used to denote the leafits of winged or 
compound leaves. They are opposite or alternate 
ending abruptly or with an odd leafit. 
Follicle.— A membranous seed-vessel of one valve and one cell. 
Foramen. — A term introduced by Grew, to denote a perfora- 
tion that is generally visible on the testa, or outer coat 
of the seed. It is the micropyle of Mirbel, and is 'al- 
ways to be found facing the radicle of the embryo. 
Fox-tail Root. — If a woody root finds its way into water, it 
is apt to protrude thousands of fine filaments from an 
elongated axis, assuming in aggregate the appearance 
of the tail of an animal. It has been called the Fox- 
tail root. 
Fringe. — The peristomium, or border of the mouth of the urn 
of the mosses, if ciliated, is denominated the fringe. 
Fracture. — If a tree is bent so as to break part only of the 
cortical and woody fibres, and the stem or branch but 
small, the parts will again unite by being put back 
into their natural position, and well propped up, but 
especially in the season of spring. Yet it will not suc- 
ceed if the fracture is accompanied with contusion, 
or if the stem or branch is large, and even where it 
succeeds, the woody fibres do not contribute to the 
union, but the granular and herbaceous substance 
only, which exudes from between the wood and liber, 
insinuating itself into all interstices, and finally be- 
