Biennial yellow sweet clover ordinarily is referred to in the seed
trade and among farmers in regions where it is grown simply as yellow
sweet clover. The plants of this species are somewhat more decumbent
the first year, and ordinarily with more deeply notched leaves than the
white-flowering species. Yellow sweet clover usually grows from 3 to 5
feet in height. This plant blooms from 10 to 14 days earlier than the
white species, and for this reason it is advisable to sow seed of both
plants when they are to be used for bee pasturage. On account of the
finer stems of yellow sweet clover it is preferred in some localities
for hay, but since it does not produce as much forage as white sweet
clover and there is much less demand for the seed, it constitutes only
a very small percentage of the total acreage. The much larger root
growth of the white species, as illustrated in figure 5, is desirable
because of the additional quantity of hummus added to the soil.
The seeds of the yellow species may usually be distinguished from those
of other species, as some of them are slightly mottled with purple. The
shape of the calyx, which is generally present on unhulled seed, and
the venation of the seed pods also distinguish it. (See fig, 1.)