98 
The Ohio Naturalist. 
[Vol. XIII, No. 5, 
curved lateral surface. Their openings are in the shape of mouths 
having their borders fringed with stiff, tapering bristles. The 
under lip of the mouth is very thick and has a cushion extending 
into the interior of the bladder. The upper lip is very thin and 
from it a transparent valve comes down to meet the inner edge of 
the cushion, thus closing the opening. By pressing against this 
valve minute plants or animals are able to enter the bladder from 
which it is impossible for them to escape, because of the valve. 
Silphium perfoliatum, Indian-cup, has its leaves arranged 
opposite each other on the stem, and united to form a cup. This 
cup is filled with water, probably partly rain and partly some 
excretion from the plant itself. 
Dipsacus sylvestris is a coarse herb having its leaves arranged 
opposite each other, forming a cup to catch water, much like the 
Silphium. Their edges and mid-ribs are covered with prickles. 
In the second group are: 
Drosera rotundifolia L. 
Drosera intermedia Hayne. 
The different forms of Drosera, Sun-dew, are usually rooted in 
damp, mossy soil or bogs. The way in which these plants catch 
their prey is by means of fine red filaments which are clavate on 
the free ends and tipped by a drop of fluid. These filaments 
stand out from the upper surface of the leaf, the under side being 
smooth and without hairs. They are of unequal length, the 
longer ones being near the outer edge, the shorter ones in the center. 
There are on one leaf, sometimes as many as two hundred of these 
tentacles. The clavate head is really a gland which secrete a 
thick, sticky, sweet fluid. It is remarkable that in making 
experiments, by placing bits of non-nitrogenous substances upon 
the leaf, the movement is scarcely perceptable, in response, while 
when insects alight upon the surface, the process immediately 
begins. In many instances the leaf itself becomes concave, so 
that when the tentacles are down, it has the appearance of a 
closely doubled fist. When the insect alights near the center of 
the leaf it is covered by the secretion of all the tentacles. 
Those in the third group are: 
Silene antirrhina L. 
Silene antirrhina divaricata Rob. 
Silene virginica L. 
Silene noctiflora L. 
Silene regia Sims. 
Silene armeria L. 
Silene conica L. 
Silene caroliniana Walt. 
Tricuspis seslerioides (Mx.) Torr. 
Carduus muticus (Mx.) Pers. 
Carduus odoratus (Muhl.) Port. 
Parsonsia petiolata (S.) Rusby. 
Polanisia graveolens L. 
Circaea alpina L. 
