This structure seems to be
present in most of the other genera in the family, judging from Flahault's
statements' we found it well-developed and properly acting in Trichosanthes
anguina, in which we hardly expected to find it, as the cotyledons are
somewhat thick and fleshy. Few cases can be advanced of a structure better
adapted for a special purpose than the present one.
[page 105]
With Mimosa pudica the radicle protrudes from a small hole in the sharp
edge of the seed; and on its summit, where united with the hypocotyl, a
transverse ridge is developed at an early age, which clearly aids in
splitting the tough seed-coats; but it does not aid in casting them off, as
this is subsequently effected by the swelling of the cotyledons after they
have been raised above the ground. The ridge or heel therefore acts rather
differently from that of Cucurbita. Its lower surface and the edges were
coloured brown by the permanganate of potassium, but not the upper surface.
It is a singular fact that after the ridge has done its work and has
escaped from the seed-coats, it is developed into a frill all round the
summit of the radicle.
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