Naturalisation in Extra- Tropical Countries. 487 



Trifolium ochroleucon, Hudson. 



Pale-yellow Clover. Middle and Southern Europe, Western 

 Asia. Perennial. This species is mnch cultivated in Upper Italy ; 

 its value is that of T. medium [Langethal]. 



Trifolium Pannonicuxn, Linne. 



The Hungarian Clover. Southern Europe. Perennial. Earlier 

 in the season than red clover, to which it is allied, but less tender 

 in foliage [Morton]. 



Trifolium pratense, Camerarius.* 



The ordinary Red Clover. All Europe, North- Africa, Northern 

 and Middle Asia. It is found wild as far north as 69 20 ' in Nor- 

 way [Schuebeler], and endures an Alpine clime. A biennial, or 

 under certain circumstances also a perennial herb, of special 

 importance for stable-fodder. The perennial variety passes under 

 the name of Cow-clover, by which name also T. medium is some- 

 times designated. Highly recommendable for permanent pastures, 

 particularly in cool humid climes, as it continues to grow year after 

 year, and produces a large amount of herbage [Dr. Curl]. It 

 prefers rich ground and particularly soil, which is not devoid of 

 potash and lime; gypsum -dressings are recommendable for the 

 fields. Perishes in stagnant moisture. It enters into the rotation- 

 system of crops very advantageously. The annual average yield of 

 hay is 40 cwt. from an acre by cutting twice, but sometimes twice 

 as much is obtained. The nectar of the flowers is much sucked by 

 bumble-bees ; this tends to facilitate the production of seeds. 

 Clovers arid Lucerne are subject to be attacked by some kinds of 

 parasitic plants, namely, species of Cuscuta and Orobanche, from 

 which fields must he held free by using well sifted seeds only, or 

 by ploughing in before the parasites come into fruit. If badly 

 infested, land be kept fallow for awhile and be periodically stirred ; 

 any Dodder-seeds, left in the soil, will germinate when broug'ht to 

 the surface, but their seedlings will die off: in the absence of the 

 foster-plant. 



Trifolium reflexum, Linne. 



The Pennsylvanian or Buffalo-Cover. Eastern North- America. 

 Annual or biennial ; flower-heads larger than those of the red 

 clover ; likes alluvial flats. 



Trifolium repens, Kivin.* 



The ordinary White Clover, called also Dutch Clover and Sham- 

 rock-Clover. Europe, North- Africa, Northern and Middle Asia, 

 sub-artic America, ascending the European Alps to 8,000 feet. In 

 Norway indigenous to lat. 70 57'. Perennial. Most valuable as 

 a fodder-plant on grazing land. It has a predilection for moist, 

 soil, but also springs again from dry spots after rain. It likes soil 

 containing potash and lime, prospers on poorer ground than red 



