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Green Needlegrass (Stipa viridula)

Plant Species
From Montana Interagency Plant Materials Handbook *
 By
S. Smoliak, R.L. Ditterline, J.D. Scheetz, L.K. Holzworth, J.R. Sims, L.E. Wiesner, D.E. Baldridge, and G.L. Tibke

Green needlegrass, also called feather bunchgrass, is a cool-season, native, perennial bunchgrass. It grows in height from 2 to 3 feet. Green needlegrass is nutritious, palatable and decreases under grazing use. Awns are not troublesome to livestock as with some other needlegrasses. Green needlegrass is frequently included in seedings of mixed midgrasses, but due partly to its hard seed coat, it may be slow to germinate and become established. It grows naturally in mixture with western wheatgrass and native gramas.

New plantings are readily established and green needlegrass is best used in mixtures with other grasses. Because the young seedlings make rapid growth and resist drought and grasshopper injury, the species has great merit for conservation use. Green needlegrass, with western wheatgrass, is especially valuable for reseeding depleted native ranges or abandoned cropland. It is very palatable to all classes of livestock and decreases sharply in production and abundance under continued intensive use.

Description

This species has rather deep, fibrous roots which in favorable situations may extend to a depth of 10 feet or more. The roots in the upper soil levels are coarse, tough and wiry, but become more fine below. The lateral extent of the root system is usually about 2 feet and the soil beneath the plant is thoroughly permeated by the profusely branching roots. Green needlegrass leaf blades vary from 4 to 12 inches in length and are usually somewhat wider than the leaves of needle-and-thread, varying from less than 1/8 inch to about 1/4 inch in width. They are usually partly rolled.

The inflorescence is a rather compact panicle varying from 4 to 10 inches in length and is usually rather greenish, or occasionally tinged with purple at maturity. Flowering takes place in early June with seed maturing in late June and early July. The seed has an awn about 1 inch in length and is covered with short hairs. The awn is not injurious to livestock. The ligule is a ring of hairs, and the sheath is hairy at the margins. Green needlegrass can remain green late into the season.

Adaptation

This grass is an important native of the Northern Great Plains, and is found as far south as Arizona. Green needlegrass grows on medium- to fine-textured soils. On medium-textured soils, green needlegrass grows with western wheatgrass, needle-and-thread and blue grama. On finer-textured soils, needle-and-thread drops out, and on even finer soils blue grama decreases leaving green needlegrass and western wheatgrass as dominants. This grass grows at all elevations up to about 5,000 feet, and is moderately drought tolerant. The chief use of this grass is grazing. It is recommended for seeding in the 12- to 18-inch precipitation zone.

Green needlegrass is very resistant to disease. It occurs only sparingly in most of the associations of native vegetation. It is distinctly less well-adapted to dry soil conditions than needle-and-thread, and occurs in greatest abundance on areas where the native vegetation has been disturbed, or in swales where moisture conditions are somewhat more favorable. It is particularly abundant in the early stages of natural revegetation of abandoned cultivated fields.

Limitations

High dormancy is a characteristic of this grass. Germinability improves for several years after harvest. Over-wintering in the soil has been observed to increase germination and emergence, so late fall seeding is recommended in preference to spring seeding. Fall and spring germination have been observed for two to three years following seeding, helping to fill in stands that were thin during their first season. Seedlings are typically slow in developing. Once established they have good vigor.

Mixtures of green needlegrass and other grasses are best for forage plantings because pure stands have been observed to partially kill out. Seed ripening progresses from top to bottom of each seed head; thus the upper part of a seed head may shatter when the lower part is not yet ready for harvest. In order to harvest the seed when the largest amount of mature seed may be obtained, the seed heads must be examined very carefully. It is seldom possible to get more than 50 percent of the seeds.

Combine- or thresher-run seed should have a purity of about 70 percent and a germination of five to 10 percent. Storage for a year usually increases such a germination to 50 to 60 percent.

Use for Hay

Green needlegrass is seldom seeded for hay production, although it is utilized for hay in native grass mixtures. In some areas green needlegrass makes up an appreciable party of the yields of native hay from upland areas or from flats. The hay is of good quality and is eaten readily by livestock. Since the seeds of this species are not troublesome to animals, it can be cut whenever it is in a favorable growth stage. Usually, however, it is not cut until August or September at the same time that associated species are cut. This is a little too late to provide the best quality of hay.

Use for Pasture

It is not recommended that green needlegrass be seeded alone for pasture, but be included as a secondary grass in pasture mixtures. Growth begins early in the spring, and continues into the fall when moisture conditions are favorable. It makes excellent recovery after grazing or clipping and provides good pasture forage throughout the season. It seems to stand up fairly well for winter grazing. Awns of this species, unlike those of needle-and-thread, cause no problem to livestock.

Seed Production

Seed yields from green needlegrass vary from 250 pounds per acre on irrigated land to 100 pounds per acre or less on dryland. Native stands produce profitable seed harvest only in years of favorable precipitation. Most commercial seed now comes from stands established for that purpose. Seed ripening is intermittent on each seed head and shattering begins as soon as the first seed is ripe. Processing to remove awns is needed before the seed can be planted with a drill.

* The Montana Interagency Plant Materials Handbook (EB69) is no longer in print, but is available for viewing in
Montana County Extension Service and National Resource Conservation Service Offices.