MAY. 168 
This genus is easily known by the shape of its leaves, and 
the heads of pea-shaped flowers. Trefoil means three leaves. 
They are very sensitive of damp, and the leaflets close under 
its influence. Abroad, some species of this genus grow to 
a height even greater than that of a man. There are seven- 
teen species, some scarce, others very common. 
TRIFOLIUM REPENS. White Trefoil, or Dutch clover. This 
is very common throughout the summer. The head of flowers 
is white, and the leaflets often have a dark spot at their 
base, with a white line bordering it near the middle. It is 
of great use in feeding cattle. 
TRIFOLIUM PRATENSE. Common purple Trefoil. LHasily 
recognized by its reddish-purple head of flowers. The leaf- 
lets are often marked also with a white spot. This is the 
common clover, so much cultivated for hay. 
TRIFOLIUM SUBTERRANEUM. Subterraneous Trefoil. This 
is a curious little species, and derives its name from the 
seed-vessels burying themselves in the ground at a certain 
period of their growth—another extraordinary variety in 
the ways of nature. The young fruit, or seed-vessel, becomes 
bent, and from the top of the branch arise many thick, short 
fibres, which bend over the fruit, and serve to bury it in 
the ground, the footstalk of the head of flowers becoming 
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