Pinegrass

Calamagrostis rubescens

Species distinguishing characteristics: 

  • Perennial, tufted grass that rarely flowers in shaded areas
  • Narrow, dense, spike-like flower cluster with short, erect branches 
  • Lemmas with an abruptly bent awn that barely protrudes beyond the glumes
  • Short hairs at the base of each lemma are less than half as long as lemmas
  • Stems with reddish bases
  • Can form extensive cover; especially in open and recently burned areas

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 sepals and petals 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 bunchgrass, 30–80 cm tall (occasionally up to 110 cm), from fibrous roots and rhizomes.  Often forms extensive cover.  In open areas, pinegrass grows more erect and forms larger tufts.  In shaded areas, growth form is much less clumped and often lacks flower heads.

Leaves and stems: 

Unbranched stems with reddish bases and 2–3 nodes along the stem.  Leaves are narrow, 2–5 mm wide and 8–40 cm long, flat or inrolled (but not folded).  Leaves are rough to touch or hairy on the upper surface and rough or smooth on the underside.  Leaf sheaths usually have distinct short tufts of hair.  Ligules, 1–5 mm long, have jagged edges at the tips.

Flowers: 

Flowering stems are abundant in open areas, recent burns, and other recently disturbed areas; otherwise, may not form flower heads.  Flower clusters, 6–15 cm long, are narrow and dense to somewhat open panicle of pale, yellowish-green to purplish spikelets on short, erect branches.  The panicle’s short branches (the longest being 2–4 cm long) make it appear spike-like; although, it often spreads out at maturity.  Each spikelet has one floret with glumes, 4–5 mm long, that are smooth, pointed at the tips, and occasionally have short, stiff hairs, especially on their keels (spines).  The jagged lemmas, 3–4 mm long, have four teeth at the tips, a stout, barely protruding awn that attaches near the base, and a strong twist or abrupt bend at mid-length.  Short callus hairs, up to 1 mm long, are at the base of each lemma and are less than half as long as lemmas.

Roots: 

Fibrous roots and conspicuous, long rhizomes that grow in the top 5 cm of mineral soil.

Seeds: 

Dark brown seeds.  Most pinegrass plants only produce seeds in open areas.

Habitat preferences: 

Dry to moderately moist soils of open coniferous forests, clearings, rocky slopes, and occasionally in meadows at low to mid-elevations.

Interesting facts: 

Sheep, cattle, and horses graze pinegrass from spring to mid-summer.  Its forage value decreases later in the season, and nutritional content is higher in open or burned, rather than shaded, areas.  Grizzly bears (Ursus arctos) and black bears (Ursus americanus)use pinegrass for forage, especially in the spring.  White-tailed deer (Odocoileus virginianus), mule deer (Odocoileus hemionus), elk (Cervus elaphus), mountain goats (Oreamnos americanus), and bighorn sheep (Ovis canadensis) graze on it until it becomes unpalatable in late summer or early fall, depending on elevation.  Mountain goats use pinegrass for feeding and bedding through September.  It is sensitive to overgrazing and can decrease in heavily grazed coniferous forests.

Pinegrass thrives with repeated fires and readily re-sprouts from its extensive rhizomes after a fire that does not completely burn the duff layer.  Pinegrass often survives or reseeds itself as a pioneer from adjacent areas even after severe wildfires. 

Native peoples used pinegrass for lining storage pits and pit-cooking rock ovens, as whisks to make Canada buffaloberry (Shepherdia canadensis) “Indian Ice Cream,” and occasionally woven for use as insoles for moccasins.

Biological Classification: