234 NOTES ON THE TEASELS, DIPSACUS SYLVESTRIS AND
Teasel" even the tips of the awns of the flowering head have this
downward inclination.
It is not easy to say what are the foes so carefully guarded
against. That there are, or have been, foes in the case of the cups
there can be no doubt; for the most careful observation will not
show that the water is in any case absorbed by the plant, or used as
nourishment.
Ants have been suggested as possible enemies, but it is hard to
see what harm they could do. The prickles in any case are not
against them. In the allied species, D. pilosus, the cup is represented
by a fringe of bristly hairs, which also is no protection against ants.
Slugs and snails in both species are guarded against ; but far more
effectively in D. sylvestris, although there is reason to believe that
no English species of Mollusca now attack the plants.
It does not seem that the prickly apparatus is directed against
the attacks of cattle, as these prickles are rarely hardened enough to
cause much inconvenience till the plant has flowered, when the
foliage will be dry and tasteless.
It may be that the prickles at an early stage guard against
molluscs, and at the last stage assist in dissemination of the seed-
heads by attaching themselves to the wool of cattle, &c.
We will now attempt to trace the mutual relationship of the two
species.
When we consider that D. pilosus has only the rudiments of a
prickly system, and a rudimentary form of cup, we infer, either that it
is a degenerate form of D. sylvestris, or, on the other hand, is more
nearly allied to an ancestral form. An examination into the struc-
ture and habits of both species will show that the latter alternative
must probably be the one accepted.
In plants of the first year it is hardly possible to discriminate
the species, both being so much alike. The configuration of the
leaf in this early stage is instructive, the limb is reduced to a rudi-
mentary fringe for nearly half the length of the mid-rib, and the
leaves may therefore be regarded as petioled. There is a tendency
to development of the sheath of the petiole equally in both species.
The epidermis is also here equally active, giving rise to occasional
prickles, and develops the serrature on the mid-ribs of the leaves of
both.
The start in the following spring appears to run for a short time on
equal lines, as the radical leaves are much alike; but a difference soon