Prairie Junegrass

Koeleria macrantha
Species distinguishing characteristics: 
  • Perennial grass, 20–60 cm tall, in scattered tufts in dry or rocky soils
  • Leaves have pointed tips and strongly ribbed on the upper surface
  • Straight, short hairs at the collar of leaf sheaths
  • Green to tan, dense flower clusters with short branches that spread during flowering
  • Flattened spikelet with 2–4 florets with pointed glumes and lemmas
  • Lemmas are awnless
  • Flower cluster is large and stout relative to the size of plant
Family Characteristics: 
  • Flowering stems have nodes and are hollow and round in cross section
  • Alternate leaves sheath the stem on their lower portion and form a hairy or membranous scale (ligule) inside the base of the leaf sheath
  • Flower clusters of numerous spikelets that attach directly to the flowering stem (spike) or attach by small stalks and are often branched (panicle)
  • A pair of bracts, called glumes (the outer/lower one being larger), enclose spikelets at the base
  • Each spikelet has one or more florets (dry, single seeded flowers) surrounded by 2 bracts (a lower lemma and a smaller, upper palea)
  • Lemmas and/or glumes may have needle-like, stiff hairs (awns)
  • Florets have 3 stamens (pollen organs) and 2 feathery stigmas (tip of female organ for receiving pollen) but lack showy petals and sepals as they are wind pollinated
  • Fruit is a seed-like grain enclosed in the bracts (called chaff in cereal grains)
  • Well-known members of this family include cereal grains such as wheat (Triticum spp.), corn (Zea spp.), rice (Oryza spp.), and oats (Avena spp.)
Growth habitat: 

Perennial grass, 20–60 cm tall, forms dense but scattered tufts with the previous year’s leaves at the base.

Leaves and stems: 

Stems are smooth or soft haired (often hairy near the top).  Light green to grayish-blue, erect or stiff ascending leaves, 1–3 mm wide and 15 cm long, attach along the lower half of stems.  Leaf blades are strongly ribbed on the upper surface, slightly pubescent to hairless, and usually folded or inrolled, but occasionally flat.  Leaves have pointed tips.  Leaf sheaths do not fuse around the stem and often have straight hairs, 1–1.5 mm long, at the joint of the leaf and sheath.  Hairy, whitish ligules, 0.5–2 mm long, that have jagged or short-fringed tips.

Flowers: 

Shiny, pale green to tan flower clusters, 2–15 cm long, in a dense, spike-like panicle with short branches, up to 2.5 cm long.  The flower cluster spreads during flowering and contracts after pollination.  Flattened spikelets, 4–6 mm long, have 2–4 florets with a pair of pointed, keeled glumes and 1 or 2 pairs of similarly shaped lemmas.  The glumes are nearly equal in size and sparse to densely short haired.  The upper glume, 4–6 mm long, is somewhat broader than the lower glume and has 3–5 nerves.  The slightly shorter lower glume has 1 nerve.  The thin, nearly translucent lemmas are about the same length as glumes, have 5 nerves, and lack an awn or have a very short one.  This species’ flower cluster can be highly varied in size and shape.

Roots: 

Fibrous root system that occasionally has rhizomes.

Seeds: 

Tiny, brown seeds inside of straw-colored seed heads.

Habitat preferences: 

Well-drained, sandy or rocky soils of open forests, meadows, and sagebrush communities at low to subalpine elevations.  Prefers full sun to partial shade.

Interesting facts: 

The common name “junegrass” refers to its habit as a cool-season grass that tends to flower in June.  The genus name Koeleria is in honor of the German botany professor George Ludwig Koeler, a grass specialist during the 18th century.  The species name macrantha means “large-flowered.”

Several species of grasshoppers and leafhoppers eat prairie junegrass; particularly those species that prefer sparsely vegetated, dry habitats.  Deer (Cervidae spp.), elk (Cervus elaphus), mountain goats (Oreamnos americanus), bighorn sheep (Ovis canadensis), and livestock graze on the early season forage.  However, it does not provide a significant amount of nutrition due to its scattered growth form and short size. 

Prairie junegrass leaves have been tied together and used as paint brushes, brooms, or used for scouring pans.  The stems have been mixed with adobe to provide tensile strength in wall building.

Prairie junegrass is an ideal species for use in prairie restoration due to its ability to recolonize severely dry or disturbed areas.  Once established, it can provide protective cover for other successional plant species that are less drought-tolerant.  Use of prairie junegrass seed from plants growing within similar environments and the presence of soil mycorrhizae may greatly boost success of restoration with this species.

Biological Classification: