ORIGIN OF THE CULTIVATED LEGUMES 259 



2. Tnfolium medium, the mammoth, giant, or pea-vine clover, 

 similar to the above, but with a growth so heavy that the stems 

 no longer stand erect but lie creeping on the ground. 



3. Trifolium repens, the common white or Dutch clover, grow- 

 ing wild in pastures everywhere in the northern United States 

 and never cultivated. 



4. Trifolium hybridum, the common alsike, similar to the 

 above only larger, with a stronger stem and a touch of pink in 

 the blossom, grown freely on moist ground for hay. 



5. Trifolitim incarnatum, the crimson or Italian clover; a 

 short erect species with a long, beautiful scarlet " head," mak- 

 ing a small quantity of good hay but rarely used by American 

 farmers, as the yield is low. 



These clovers are all leguminous plants and all serve the 

 same purpose as soil restorers so far as nitrogen is concerned. 

 The farmers' choice therefore turns on the question of yield 

 and general usefulness. 



This rules out white clover as a cultivated crop, but it has no 

 difficulty in maintaining itself as a wild plant, 1 to the great ad- 

 vantage of our self-sown native pastures. 



The scarlet clover is but recently introduced into cultivation. 

 According to Candolle it exists wild in Gallicia, in Biscaya and 

 Catalonia, as also in Sardinia, in Algiers, and in the valley of the 

 Danube, in some of which places it may have been introduced 

 since cultivation. It is surely indigenous in the neighborhood 

 of the Pyrenees and also along the coast of Cornwall, where it 

 is associated with a yellow variety which is truly wild also on 

 the continent. 2 



This shows how the process of domestication is sometimes 

 long deferred, and may even be abandoned if, after trial, the 

 species is not found worthy, as will more than likely be the 

 case with this particular clover. 



1 In this respect it rivals Kentucky blue grass, with which it is often asso- 

 ciated, an association clearly advantageous to the blue grass, whose supply of 

 nitrogen is thereby better assured. 2 " Origin of Cultivated Plants," p. 106. 



