BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Achnatherum richardsonii | Richardson Needlegrass 



GENERAL BOTANICAL CHARACTERISTICS : 
Richardson needlegrass is a native, perennial, cool-season bunchgrass.
This fine-stemmed, tufted grass grows from 16 to 40 inches (40-100 cm)
tall [10,18].  The inflorescence is open and diffuse [18].  Culms are
glabrous or slightly hairy.  Blades are typically involute and
subfiliform and reach heights of about 6 to 10 inches (15-25 cm) [14].
The seeds of Richardson needlegrass are hard, slender, and cylindrical,
and have a sharp, pointed base (callus) and long, twisted awns [31].

Richardson needlegrass is a shallow-rooted species; the abundance of
roots decreases as soil depth increases.  Clay accumulation restricts
root penetration of Richardson needlegrass [22].  Richardson needlegrass
becomes dormant following depletion of surface soil moisture during the
latter part of the growing season [22].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte


REGENERATION PROCESSES : 
Richardson needlegrass reproduces sexually.  The twisted awns of the
seeds expand and contract with variations in temperature and moisture,
drilling them into the soil [31,36].  Strong winds may transport seeds a
considerable distance, especially when awns are twisted together in
clumps.  Animals also carry seeds as the awns become trapped in their
fur [36].


SITE CHARACTERISTICS : 
Richardson needlegrass is common on hillsides and dry plains, in open
grassland or sagebrush benches, and in bottomlands, swales, and wooded
slopes [3,10].  It is also found on moraines and gravel outwash
associated with streams [3].  In Montana, Richardson needlegrass is
found on mountain slopes on both sides of the Continental Divide at
elevations of 3,000 to 7,000 feet (900-2,100 m) [21].  In north-central
Colorado, it is found in mesic sites at 8,000 to 8,600 feet (2,400-2,580
m) [13].  In Wyoming, Richardson needlegrass is commonly found at
elevations of 7,000 to 8,500 feet (2,134-2,591 m) and occasionally at
elevations of 9,000 feet (2,743 m) [3].

Soils:  Richardson needlegrass is common on slightly acidic to neutral
soil (pH 6.6-7.3) [19].  Soil textures vary from fine sandy loam to
clayey loam.  Cation exchange capacity is moderately high, but soils are
considered of low fertility because of low levels of nitrogen and
phosphorus [19].


SUCCESSIONAL STATUS : 
Obligate Climax Species

Richardson needlegrass is a climax codominant on sites in Glacier
National Park and on fescue grasslands of western Canada [16,19].  It
occurs in the rough fescue prairie association, a climax community type.
However, the equilibrium between prairie and associated forest
vegetation is not always clear.  Woody species such as willows (Salix
spp.) and poplars (Populus spp.) are tending to invade the fescue
prairie of Alberta, though the effects of fire, mowing, and limited
grazing may serve to counteract this tendency.  It has been suggested
that white spruce (Picea glauca) may be considered as the theoretical
climax for much of the fescue grassland or black soil region of Alberta;
however, natural burning tends to prevent this cimax from being realized
[39].
 


SEASONAL DEVELOPMENT : 
Most needlegrasses begin vegetative growth in the early spring, usually
before associated grasses green up, and continue growing throughout the
summer if enough moisture is available [31,32].  Needlegrasses flower
from July to September [31].  No specific information on the seasonal
development of Richardson needlegrass was found.

Related categories for Species: Achnatherum richardsonii | Richardson Needlegrass