Issue: July 21, 1997

Yellow wildflower, sweet clover, alfalfon

There is a yellow flowering plant growing along the roadside near my home and I've noticed it in a lot of other places. Sometimes it covers large areas of open fields. It is quite pretty, even though the individual flowers are very small. I've enclosed a sample. Can you identify it and tell me a little about it?

The sample you sent was from a plant called yellow sweet clover; in New Mexico it is sometimes called alfalfon. Frank Holguin, Valencia County Extension Agent, New Mexico State University, Cooperative Extension Service, recalls that his father and grandfather always called it alfalfon and considered it a desirable addition to the pasture. I have seen it along roadsides in many parts of New Mexico; in some areas white sweet clover is more common than the yellow form. You will notice that they have a distinctive, strong smell when they are cut or bruised. They are creating a colorful display this year.

This plant is a biennial which grows one year not making much of a show of its presence, then the second year produces a flower stalk, flowers, produces seeds, and dies. This year it is so noticeable because late last summer and through the winter we had considerably more precipitation than usual. This allowed the plants to grow and flower well this year. Many of the seeds produced this year will lie dormant in the soil awaiting another series of moist seasons such as we have just experienced. Some seeds will sprout in dry years but only in a series of moist years are we likely to see a repeat of this year's colorful display.

By the way, the name alfalfon refers to the fact that it can be planted to produce forage and hay like its relative alfalfa. However, alfalfa is a perennial and more commonly grown now for forage than the sweet clovers. Like alfalfa, sweet clover is a legume capable of extracting nitrogen from the air and enriching the soil. For those who consider harvesting it for hay, Bill Neish, Torrance County Extension Agent, New Mexico State University, Cooperative Extension Service, advises that it is important that it be cured properly after cutting or can cause livestock problems. For those who want to enrich the soil, it only needs to be plowed into the soil and allowed to decompose.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!