124 FODDER AND PASTURE PLANTS. 
YELLOW TREFOIL (Medicago lupulina L.) 
Plate 22: Seed, Plate 27, Fig. 35. 
Other English name: Black Medick. 
Botanical description: Trefoil is closely related to the 
Lucernes but is shorter lived. It is generally biennial but sometimes 
lives only one year. It has a taproot with comparatively few 
branches, about a foot deep on an average. The stems, which are 
developed in great number from the crown of the root, are decumbent 
or ascending. They often creep along the surface of the soil but 
do not produce secondary roots. The plants are therefore spreading 
in habit, especially as the stems are usually much branched. The 
leaves consist of three leaflets, each of which hasa short stalk. The 
flowers are yellow, much smaller than those of the other species of 
Medicago mentioned, and in a short cylindrical head. Trefoil closely 
resembles certain yellow-flowered species of clover (Trifolium) but 
can be readily distinguished from them. In true clovers the blossoms 
do not fall off when flowering is over, but remain, withered, until 
the fruit is ripe, making the heads brown and hiding the pods. In 
Trefoil the blossoms fall off as soon as flowering is passed and the 
pods are therefore visible while ripening. They are small, kidney- 
shaped, rough-ridged and black—hence the name Black Medick. 
Each pod contains only one seed and falls off without breaking. 
Geographical distribution: Trefoil is indigenous to all Europe 
except its most northern parts, to northern Africa and to western 
Asia. It is not a native of North America but is rather common 
all over the continent, mostly growing like a weed. 
History: It has been cultivated in England for about one 
hundred and fifty years. From the beginning of the nineteenth 
century it began to be better known as a forage plant over central 
Europe. It is not cultivated in Canada to any extent. In the 
eastern provinces it is commonly found as an impurity in Red Clover 
and Alsike and must then be considered a weed, as it is overripe when 
the clovers are ready to cut. 
Cultural conditions: On account of its rather shallow root 
system, Trefoil is more independent of the subsoil than the lucernes 
and most clovers. It makes fairly good growth on rather poor land 
but succeeds best on soils not too stiff and wet. Lime is necessary 
for its proper development and a liberal amount of potash and 
phosphoric acid is beneficial. 
