Thurber's Needlegrass - Range Plants of Utah
Achnatherum thurberianum (Piper) Barkworth
Scientific Name Synonyms:
Stipa thurberiana Piper
Life Span: Perennial
Growth Characteristics: Thurber’s needlegrass is a densely tufted bunchgrass with erect culms (stems), 12 – 24 inches tall. The crown typically acquires a circular appearance, as the plant dies from the center outwards. The fibrous roots reach up to 2 feet deep. It begins growth in early spring, fruits from May to June, and seed ripens in late July. It continues growth until October. It often goes dormant through the summer and may green-up in the fall is soil moisture is adequate. It reproduces from seeds and tillers.
Seedhead: Panicle is 3 to 9 inches long with single-flowered spikelets with sharp points and awned lemmas. The seed is about ¼ inch long. The awn is twice bent, over 5 inches long, and has short hairs on all but the tip. The glumes are greenish or purple-tinged.
Leaves: Leaf blades are rather narrow (<¼” wide), and 6 -10 inches long. The edges of the leaves are rolled upward and in.
Thurber’s needlegrass is commonly found in semiarid landscapes, and is most prevalent on north and east slopes where there is more moisture and less temperature variation. It is very drought and cold tolerant, but is not tolerant of shade, and saline or sodic soil conditions. It occurs in areas with 7-16 inches precipitation, and elevations from 3500 to 6500 feet. In Utah, it is only known to occur in Box Elder and Juab counties, most likely on the western side.
Soils: Occurs on a variety of soil types, most of which are dry and coarse-textured.
Associated Species: Associated species in Utah include Big sagebrush, Utah Juniper, Curlleaf mountain mahogany, Gambel oak, Fourwing saltbush, Horsebrush, Antelope bitterbrush, Winterfat, Sandberg bluegrass, Indian ricegrass, Bluebunch wheatgrass, Thickspike wheatgrass.
Uses and Management:
Thurber’s needlegrass is valuable forage for livestock and wildlife. It is most palatable in the spring and early summer while the plants are young and succulent. As the species matures, animals avoid grazing Thurber’s needlegrass as the leaves become somewhat tough and the sharp pointed callus and awns can be injurious to eyes, ears, nose, tongue, and throat. It does cure well and provides fair to good winter forage. Small and medium-sized animals depend on Thurber’s needlegrass for cover; sage grouse use it for nesting as well.
Thurber’s needlegrass is sensitive to overgrazing. A single defoliation, particularly during the boot state, can reduce subsequent herbage production and root mass and possibly lower the competitive ability of Thurber’s needlegrass. A grazing system which allows seed production, trampling of plant seed, and a non-use period may increase the establishment of new plants in interspaces. A deferred rotation grazing system is recommended.
Although it can regenerate through tillers, after fire regeneration is almost entirely by seed. Reestablishment on burned sites may be relatively slow due to low germination and seedling vigor.
When seeding Thurber’s needlegrass, it has shown to have higher success when drilled in to deep furrows rather than broadcast. Seed should be planted ¼ to ½ inch deep. When using seed, the best success is reached when using seed from a source within 500 miles of the planting site.
Thurber’s needlegrass is distinguished from Needle-and-Thread (Hesperostipa comata) by having glumes that are less than 15 mm long, and by being conspicuously hairy on the lower part of the awn. It is also known to hybridize with closely related species, Indian Ricegrass (Achnatherum hymenoides), creating the hybrid Achnatherum x bloomeri.