Silver bluestem (Bothriochloa saccharoides) is a unique, attractive bunchgrass that derives its name from its silky white inflorescences. These silvery plumes range from 2-1/2 to 6 inches in length and obtain their distinctive appearance from their short, bent awns. Another name this species has received from its appearance is silver beardgrass.
As befitting a bluestem grass, the round stems are usually purplish near the base. Unlike more famous varieties of bluestem, however, silver bluestem is not quite upright in its growing habit, being rather crooked due to kinking and branching at the nodes. The stems vary from 18 to 42 inches in height.
The leaves of silver bluestem may be flat or folded and measure from one to ten inches in length. They are no more than 1/4 inch wide. The leaves are mostly hairless and are frequently covered with a bluish waxy substance. The margins may feel slightly rough to the touch, and are sometimes (but not always) notched. The midrib is prominent. The whole leaf tapers to a point.
Look carefully at the base of the leaf to note a few characteristics you might otherwise miss. The nodes are typically ringed with short, white hairs. Inside the short sheath, note the membranous ligule that protects the sheath from water. On the outside of the sheath, look for a waxy or sparsely hairy collar.
Silver bluestem can be found across Kansas on a variety of dry, sunny sites, including prairies, roadsides, and rocky slopes.
It is most likely to be seen on loam, clay loam, or clay soils with a bedrock of limestone. However, it is capable of thriving on sandy soils as long as its other needs are met. Its preferred pH is between 6.5 and 7.2.
This species is a perennial warm-season grass. It begins growing in the spring once the daytime temperature starts to average 70° to 75°F.
Because silver bluestem does not produce rhizomes, it must compensate by producing many seeds very quickly. It may begin to develop seedheads within a month of starting growth and can flower nearly all summer long and into September. The seeds only take four to six weeks to ripen. When weather conditions permit, silver bluestem may produce several seed crops each year.
Silver bluestem is an invasive pioneer grass with the ecological role of quickly covering disturbed or exposed soils, whether found on overgrazed pastures or abandoned acreage that was formerly tilled. It can even compete successfully against some non-native invaders.
The inflorescences of silver bluestem attract butterflies, while birds eat the seeds. Some mammals will graze the plants themselves.
Silver bluestem is a rather tricky pasture plant. It offers fair nutritional value to most types of livestock in the spring while it is still young. Once it produces seedheads (which it does quickly) it loses most of its palatability, although goats seem to relish the immature seeds. Silver bluestem once again offers some forage value in winter when included in a hay mix or when it is dormant, provided that the livestock receive protein supplements. Most livestock producers probably do not want to plant silver bluestem, however, as it will take over the entire pasture if overgrazed. If keeping some silver bluestem on the pasture is a priority, this can easily be done by allowing livestock to graze no more than 50% of the plant and by giving the plants 1-1/2 to 2 months in the spring every two or three years to go to seed.
The attractive silvery inflorescences of this plant suit it well to landscaping. Silver bluestem is particularly well adapted to xeriscaping, the art of landscaping with plants that require no watering. This species can even be left to stand over the winter, adding interest to a garden that would otherwise be barren. The least expensive way to obtain silver bluestem seed is to collect dry seedheads whenever you encounter them in nature. Plant the seeds in the desired location any time after the last spring frost. Silver bluestem will reproduce itself quite efficiently in future years, so deadhead the majority of the plants to keep them under control.
The Kiowa people used dried stems for toothpicks.
Silver bluestem is invasive, particularly in areas that are subject to overgrazing and soil disturbance. Maintaining the health of the broader plant community is key to avoiding an overabundance of silver bluestem.
Yellow bluestem is an invasive Old-World species that was introduced to the United States in the 1920s, and its inflorescence is remarkably similar to that of silver bluestem. Examine the texture and color of the dorsal side of the spikelet. A silver bluestem spikelet will be smooth and uniform in color, while a yellow bluestem spikelet has furrows and a purplish tip. Now for some measurements. A silver bluestem spikelet will measure 3.5 to 4.0 mm compared to 4.0 to 5.0 mm for a yellow bluestem spikelet. Also measure the hairs at the tip of the pedicel. Silver bluestem hairs will be 5.0 to 7.0 mm long, compared to 2.0 to 3.0 in yellow bluestem.
Parts of a Grass Plant: A Glossary
Definitions for technical terms used in this post.