curved hooks or bent and barbed hairs which catch
upon the wool of sheep, the coat of cattle, or the nether integuments
of wayfaring humanity, and can't be got rid of without some little
difficulty. Most of them, you will find on examination, belonged to
confirmed hedgerow or woodside plants: they grow among bushes or low
scrub, and thickets of gorse or bramble. Now, to such plants as these,
it is obviously useful to have adhesive fruits and seeds: for when
sheep or other animals get them caught in their coats, they carry them
away to other bushy spots, and there, to get rid of the annoyance
caused by the foreign body, scratch them off at once against some
holly-bush or blackthorn. You may often find seeds of this type
sticking on thorns as the nucleus of a little matted mass of wool, so
left by the sheep in the very spots best adapted for the free growth of
their vigorous seedlings.

Even among plants which trust to the involuntary services of animals in
dispersing their seeds, a great many varieties of detail may be
observed on close inspection. For example, in hound's-tongue and
goose-grass, two of the best-known instances among our common English
weeds, each little nut is covered with many small hooks, which make it
catch on firmly by several points of attachment to passing animals.
These are the kinds we human beings of either sex oftenest find
clinging to our skirts or trousers after a walk in a rabbit-warren. But
in herb-bennet and avens each nut has a single long awn, crooked near
the middle with a very peculiar S-shaped joint, which effectually
catches on to the wool or hair, but drops at the elbow after a short
period of withering. Sometimes, too, the whole fruit is provided with
prehensile hooks, while sometimes it is rather the individual seeds
themselves that are so accommodated. Oddest of all is the plan followed
by the common burdock. Here, an involucre or common cup-shaped
receptacle of hooked bracts surrounds an entire head of purple tubular
flowers, and each of these flowers produces in time a distinct fruit;
but the hooked involucre contains the whole compound mass, and, being
pulled off bodily by a stray sheep or dog, effects the transference of
the composite lot at once to some fitting place for their germination.

Those plants, on the other hand, which depend rather, like London
hospitals, upon the voluntary system, produce that very familiar form
of edible capsule which we commonly call in the r