- New YorK AGRICULTURAL EXPERIMENT STATION. Zi 
Up to the time of blooming, yellow trefoil and alfalfa are so much 
alike in appearance that they are separated with difficulty except by 
one who is well acquainted with them. This is especially true in 
the earlier stages of growth. ‘The seedlings of the two species are 
strikingly alike. (Compare Plates XXI and XXII.) The writers 
have sought in vain for morphological or anatomical differences by 
means of which one unfamiliar with the plants might distinguish 
one from the other with certainty. Yellow trefoil plants vary 
greatly in habit according to their environment. In lawns they 
spread their branches close to the ground, and blossom and seed in 
spite of frequent close mowing. Among clover and alfalfa they 
grow more upright and may attain a height of over two feet. But, 
in general, yellow trefoil is smaller than alfalfa, more spreading in 
habit and the leaflets are broader in proportion to their length. The 
most reliable characters by which the two species may be separated 
in early spring are (1) The habit of growth of the crown; and 
(2) the character of the root system. ‘The stems of yellow trefoil 
being procumbent, the crown has a spreading habit and lies close to 
the ground; while the crown of alfalfa is upright in habit. The 
root systems offer a more striking contrast. Alfalfa has a large 
tap-root with very few side roots; while yellow trefoil has a small 
tap-root which is nearly concealed in a mass of fibrous side roots. 
(see Plate XXITI.) 
Yellow trefoil is not a troublesome weed. No special methods 
are required for its eradication. It readily succumbs to tillage. 
Nevertheless, its substitution for alfalfa is objectionable because, 
as a fodder plant, it is greatly inferior to alfalfa. It makes but a 
small amount of hay and dies after the first cutting of the second 
season, whereas alfalfa is perennial. 
In parts of Europe yellow trefoil is sometimes sown for sheep 
pasture, but in America it is not considered worthy of cultivation. 
Although it grows spontaneously in meadows, pastures and lawns 
and along roadsides throughout the greater part of New York it is 
rarely found in quantity except where adulterated alfalfa or clover 
seed has been used. The yellow trefoil seed imported into the United 
States from Europe is practically all used for the adulteration of 
alfalfa and clover seed.®4 
* Brown (9). 
