LEGUMINOS^ 433 



Geographical. — There arc close to 300 species of Trifotium, most of which 

 occur in the north temperate regions; a few, however, also occur in South 

 America and South Africa. They are distributed from low to high altitudes. 

 Besides those given in the following key, two others, T. suaveolens (Shaftal 

 or Persian clover) and T. alexandrinum (Berseem) are grown to some extent 

 in the United States. 



Kev to Principal Species of Trifolium 



Flowers in spike-like heads, much longer than thick, T. incarnatum 



(crimson or scarlet clover). 

 Flowers in globular or ovoid heads. 



Corolla white or yellowish-white, sometimes touched with pink; stems 



creeping, T. repens (white clover). 

 Corolla red, red-purple, or rose-colored; stems erect or nearly so. 

 - Flowers pedicelled; stipules acuminate (Fig. 183, A), T. hybridum (Alsike 

 or Swedish clover). 

 Flowers sessile; stipules abruptly acute (Fig 183, D). 

 Blade of leaflet marked with large spot; heads sessile, T. pratense 



(red clover). 

 Blade of leaflet without spot; heads stalked, T. medium (mammoth 

 or zigzag clover). 



TRIFOLIUM REPENS (White or Dutch clover) 



Description. — This is a low, smooth, perennial herb aris- 

 ing from a straight tap root. The root system is shallow. 

 The plant possesses creeping stems which develop adventi- 

 tious roots at the nodes. The long-petioled, trifoliate leaves 

 have inversely heart-shaped or notched leaflets and narrow, 

 membranous stipules. The inflorescence is a head and is 

 borne on a long flower stalk which arises in the leaf axils. 

 The flowers are small, fragrant, and white or pinkish. They 

 are erect at first, but become deflexed when mature. The 

 visitation of insects is necessary for the production of a 

 good crop of seed. The small pods are usually four-seeded. 

 The seeds vary a great deal in their longevity. Germination 

 of so-called "hard seeds" may be delayed several years in 

 the soil. Such seeds usually show up in germination tests. 

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