
ECOLOGICAL CLASSIFICATION OF PLANTS — 
insect stimulates the glands, which after a few hours pour 
-out a distinctly acid juice, by means of which the insect 1s 
digested. 
oe Some plants are total parasites, getting their 
(c) Parasitic f04 from other plants, which are called their 
and pee wige oie 
Saprophytic “hosts”; these have little or no chlorophyll—e.9., 
ple. Toothwort, Broomrape, Dodder. Other parasitic 
plants are only partly so; they get some of their food from 
the plant on which they live, but they also get a good deal— 
perhaps the greater part—just as an ordinary green plant 
does. These semi-parasitic plants may again be subdivided 
into — 
1. Those with roots of their own and leaves, ¢.g.—Hye- 
bright, Bartsia. 
2. Those that have green leaves, but no true roots—e.g., 
Mistletoe. 
Toothwort (Lathrwa squamaria) is parasitic on the roots of 
trees, such as ash, poplar, hornbeam, hazel, in fact on almost 
any angiospermous tree. It lives entirely underground except 
fora short period, when it sends up a few flower-bearing 
shoots. It has no roots of its own, but attaches itself by 
suckers to the roots of the tree on which it is living. Certain 
cells in the sucker are especially adapted for the absorption of 
nourishment from the root. The subterranean stems are. 
white, and are covered throughout their entire length with 
thick, scaly leaves similar in colour to the stem. It is stated 
that these leaves are also insectivorous, forming traps some- 
what similar to those of the Bladderworts. In the spring, 
inflorescences arise from the extremities of the subterranean 
scaly shoots. They are purplish in colour and at first crook- 
like, but they straighten themselves by the time the fruit 1s 
formed so that it may ripen thoroughly. 
The union of the Broomrape (Orobanche) with its host is so. 
close that it is difficult to say where the one ends and the 
other begins. The Broomrapes are very select in the choice 
of their hosts: thus one species lives exclusively on Worm- 
wood, another on Butterbur, a third on the Wood Sage, etc. 
