Sand dropseed (Sporobolus cryptandrus) is rather unremarkable in appearance. The plant is supported by a root system that can reach down to eight feet deep and spread to two feet wide. Sand dropseed ranges in height from 16 to 40 inches. The stem is variable, being either erect or decumbent, single or branched, flat or grooved on one side.
The leaves may be flat or may roll inward. They vary from 2 to 10 inches in length and are up to 1/4 inch wide. These leaves have whitish margins and taper to thin points. The top side is rough to the touch. The leaf collar is characterized by a tuft of white hair, each hair growing up to 0.16 inch long.
The flower is a purplish or lead-gray panicle. Its pyramidal shape may not be obvious at first, as it starts out tight and spike-like and only spreads out with maturity. The base often remains enclosed in the upper sheath. The branches of the inflorescence are slender and about three inches long with spikelets crowded near the ends. The spikelets are only a tenth of an inch long or so.
The seeds of this plant are numerous and very small. They have no awns.
Sand dropseed can be found throughout much of North America and Kansas, growing in pastures and open disturbed areas, including along roadsides.
This species prefers sandy soils, but can adapt to a somewhat heavier texture as long as the soil is dry. Sand dropseed is adapted to a fairly broad range of moderate pH levels and can thrive on sites low in soil nutrients.
This plant requires full sun to grow well.
A warm-season perennial, sand dropseed is made to grow and reproduce during periods of intense drought. It copes by rolling up its leaves to minimize evapotranspiration. This is an excellent adaptation for this plant, because it flowers in the hot, dry months of July and August, as well as September.
The genus name Sporobolus comes from the Greek words sporos or “seed” and bolos or “throw.” This is an apt name for sand dropseed, as it produces seed prolifically and often parts with the seed by forcibly launching it from the inflorescence.
Sand dropseed resists winter dormancy longer than many species, particularly on sandy soils.
A native of the shortgrass prairie, sand dropseed plays a valuable role as a pioneer plant in disturbed or drought-damaged areas. While this trait can make the species rather invasive on sand, it does serve to stabilize such soils with extensive root systems.
In southwestern Kansas, sand dropseed provides much-needed shelter for the lesser prairie chicken. Some birds (particularly bobwhites) and small mammals will eat the seeds. Sand dropseed has little forage value, although deer and pronghorn antelope will graze it in winter if nothing else is available.
Sand dropseed can be used as pasture, but with mixed results. It is fairly palatable during the early stages of growth, although it is low in protein. It quickly becomes unpalatable as it matures. Its tendency to stay green well into the winter gives it potential as a cold-season pasture plant, but it is important to note that it is deficient in phosphorus and carotene, as well as protein. Overgrazing may result in sand dropseed taking over the pasture.
Where sand dropseed really excels is in the stabilization of disturbed areas, particularly those with sandy soils. It requires a cold spell for good germination, so seed in the fall or very early in the spring into a firm, moist, weed-free seedbed. If planting in a monoculture, seed at a rate of 1/2 to 1 pound pure live seed per acre. The seed can be sown broadcast, or it can be drilled at a depth of 1/8 inch, slightly deeper in coarse soils. Follow up with a light harrowing to ensure good contact with the soil. Be aware that sand dropseed is difficult to establish. It will not achieve its hallmark drought tolerance until the stand is well developed. Do not graze for at least two years after planting.
The Apache, Navajo, and Hopi tribes had several uses for sand dropseed. The seeds could be used as a grain in bread and porridge, while the plant itself could be made into a cold infusion to treat sores on the legs of horses.
Sand dropseed can be a problem weed in pastures because cattle will avoid it in favor of more palatable grasses. This problem can be remedied by using a management system that does not allow for selective grazing. Repeated close grazing of sand dropseed will eventually kill it.
This species can be confused with sand dropseed in the early stages of growth. However, close attention to the leaves will easily reveal the differences. Scribner dichanthelium has significantly wider leaves. Its foliage is also a darker shade of green.
Parts of a Grass Plant: A Glossary
Definitions for technical terms used in this post.