In the United States, birdsfoot trefoil is grown for hay and permanent pasture, primarily in the New England States and western Oregon, and to a limited extent in several other Central and Northern States. Practically all big trefoil seed is produced in Oregon.
Trefoil is a perennial plant that has an extensive root system with a strong taproot.
It is therefore more drought-resistant than many other legumes. If conditions are unfavorable, the plant may grow only a few inches tall, but if favorable it may produce 100 or more stems and reach a height of 3 feet. Ten or more seed are produced in a cylindrical pod an inch or more long. Several seed pods are attached to the stem at a single point, and toward maturity they spread apart on a lateral plane giving the appearance of a bird's foot. The pods dehisce or pop open on maturity and the seeds are scattered.