THE MOVEMENTS OF PLANTS. 
197 
kind.* An interesting modification of tlie process occurs in 
stolons or runners, which consist of much elongated flexible 
branches, that run along the surface of the ground and form 
roots at a distance from the parent plant ; the circumnutation 
is so great in amplitude, that it may almost be compared with 
that of climbing plants. The stolons are thus aided in passing 
over obstacles, and in winding between the stems of surrounding 
plants. 
Peduncles. — Flower stems form no exception to axial struc- 
tures in the habit of circumnutating ; but the effect is curiously 
modified by geotropism in the case of Trifolium subterraneum, 
and by apheliotropism in that of Cyclamen Persicum , in both of 
which plants the object gained is the burying the unripe pods 
beneath the soil, leaves, &c. The flower-heads of Trifolium 
subterraneum produce but three or four perfect flowers at the 
base, all the other flowers above consisting only of cylindrical 
calyx-tubes with stiff spreading lobes, forming claw-like pro- 
jections (PL Y. figs. 4-6). As soon as the perfect flowers 
wither, they bend back upon the peduncles. This movement 
is due to epi nasty, a word coined to imply that the upper surface 
of an organ grows more quickly than the lower surface, and 
thus causes it to bend downwards. Whilst the perfect flowers 
are thus bending, the whole peduncle curves downwards and 
increases much in length, even from 6 to 9 inches if necessary, 
until the flower-head reaches the ground. At this period the 
younger, imperfect, central flowers are still pressed closely 
together, and form a rather rigid conical projection. The 
depth to which the flower-heads can penetrate varies from 
•25 to *06 inch. In the case of a plant kept in the house, a 
head partly buried itself in sand in 6 hours ; with plants grow- 
ing out-of-doors, Mr. Darwin believes that they bury themselves 
in a much shorter time. After the heads are buried, the 
central aborted flowers increase considerably in length and 
rigidity, and become bleached ; they gradually curve, one after 
the other, upwards or towards the peduncle (fig. 5). In thus 
moving, the long claws on their summits carry with them some 
earth ; hence a flower-head which has been buried for a 
sufficient time forms a rather large ball, the aborted flowers 
having caught up the earth with the claw-like sepal-lobes, act 
somewhat like the hands of a mole, which force the earth back- 
wards and the body forwards. 
The calyxes of all the flowers are clothed with simple and 
multicellular hairs (fig. 7), which, on absorbing carbonate of 
ammonia presented to them, exhibited protoplasmic aggrega- 
# For full description of twiners and other climbing plants, the reader is 
referred to Mr. Darwin’s work on The Movements and Habits of Climbing 
Plants. See also Pop. Soi. Rev. vol. v. p. 55. 
