171 BRITISH PHANEROGAMIC PARASITIC PLANTS. 
not uncommon plants, growing in bog marshes and damp pastures. 
Both plants are much alike in general appearance. Sytvatica has a 
procumbent habit, branched from the base. Patustris is upright 
and branched above, the leaves are very much cut and divided, and a 
novice could easily mistake them for a small fern when growing 
among SpHacnum. ‘These plants attach themselves to grasses and 
sedges, but, as in the preceeding, the attachment is very frail. I 
have an idea that they are sometimes attached to SpHacnum. This 
Summer I examined a large number of plants on a bog at the foot of 
Snowdon and could not see anything else for them to be attached to; 
but, on the other hand, it is quite possible that there were small 
roots of cotton grass and little sedges that I did not see. The name 
Louse Wort is given because it is said that sheep feeding on these 
plants are soon affected with disease and covered with vermin. But 
asa fact animals will not eat them if any other food is to be found, 
and as they always grow on swampy land such situations have a bad 
effect on the health of sheep and other animals. 
RHINANTHUS CRISTA-GALLI (Yellow-rattle) is one of the most 
common plants among mowing grass. It is a plant that seems to 
have a very short existence, coming up in the spring and growing up 
with the grass. It flowers early, May and June, the seed soon ripens 
and is often shed by the time the grass is cut for hay. It may be 
that this plant, going through its reproductive process so quickly, 
requires more nourishment than it can derive from the air and soil, 
hence its partial parasitism. The attachment in this case is frail as 
with others mentioned. 
MELAMPYRUM PRATENSE (Cow-wheat) is common in open woods, 
on heaths, etc., is a straggling, wiry plant, 6 to 18 inches in height. 
It attaches itself to roots of grasses, it also has a short existence, and 
never looks a thoroughly healthy and vigorous plant, withers in a few 
minutes when taken out of the ground, and very soon turns black. 
There are 3 other species of the genus all rather rare. 
THESIUM HUMIFUSUM (the Bastard Toad-flax) is the only British 
species of the SanraLacEs, all of which are parasitic on roots. 
