BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Poa cusickii | Cusick's Bluegrass 



GENERAL BOTANICAL CHARACTERISTICS : 
Cusick's bluegrass is a cool-season, native perennial bunchgrass. It
grows in dense, often large tufts.  Culms are 8 to 24 inches (20-60 cm)
long [14].  Cusick's bluegrass is dioecious with apomictic subspecies
and races in which only pistillate plants are present [35].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte


REGENERATION PROCESSES : 
Cusick's bluegrass reproduces from seed and by tillering [20].
Predominantly to entirely female populations are common.  All Poa
cusickii ssp. purpurascens plants are pistillate [35].  Both sexual and
apomictic races produce viable seed [34,35].  Cusick's bluegrass stores
seed in the soil.  More Cusick's bluegrass germinated from seed in soil
samples collected on plains rough fescue (Festuca altaica ssp. hallii)
prairie in Saskatchewan than from seed of any other grass species,
including plains rough fescue [10].  Germination rate of seed collected
from mixed-grass prairie in Saskatchewan was 42 percent [56].


SITE CHARACTERISTICS : 
Cusick's bluegrass occurs mostly on dry sites.  It grows on rocky
slopes, terraces, dry margins of meadows, and inactive floodplains
[4,5,18,20].  It has shown minor coverage on moist sites [24].

In eastern Washington, Cusick's bluegrass tends to be restricted to
north-facing slopes in the basin big sagebrush (Artemisia
tridentata)/bluebunch wheatgrass habitat types.  In many stands,
Cusick's bluegrass occurs primarily beneath canopies of shrubs,
particularly big sagebrush and spiny hopsage (Grayia spinosa) [4,5].
Cusick's bluegrass occurs on all aspects in eastern Oregon [44].

Cusick's bluegrass occurs mostly on loamy-textured soils [17,29,44].  In
Wyoming, it grows on Cryoboroll soils [25].  In eastern Oregon, Cusick's
bluegrass is an indicator species for meadows with pumice soils and dry
sagebrush (Artemisia spp.) floodplain sites [20].

Cusick's bluegrass occurs at mid- to high elevations [18]  The
elevational range of Cusick's bluegrass in several western states is
reported below [6,18].

          feet            meters
       ------------     -----------
CA     4,440- 7,000     1,330-2,100 (in Warner Mts.)
CO     6,200-12,800     1,890-3,902    
MT     6,600-10,000     2,012-3,049    
OR     4,440- 5,500     1,330-1,650
UT     8,700-11,800     2,012-3,597    
WY     7,000-12,500     2,134-3,811 


SUCCESSIONAL STATUS : 
Little is known of Cusick's bluegrass' place in succession.  In
floodplain succession, Cusick's bluegrass does not occur on new
floodplains.  Instead, it occurs on inactive floodplains and dry
terraces [18].  Cusick's bluegrass is a minor component of big
sagebrush/bluebunch wheatgrass and other climax habitat types [3].


SEASONAL DEVELOPMENT : 
Phenological decelopment of Cuisck's blugrass in most states has not
been described.  In Montana, Cusick's bluegrass flowers from June to
August [6].

Wet weather can extend reproduction and growth period of Cusick's
bluegrass.  In Washington, Cusick's bluegrass flowered and continued
growing for a longer period of time after the unusally wet fall and
winter of 1973-1974 than after the dry winter of 1973-1974.
Precipitation during the fall and winter of 1972-1973 was 5.4 inches
(135 mm); preciptation the fall and winter of 1973-1974 was 15 inches
(375 cm).  Mutton grass phenology was as follows [31]:

                     1972-1973       1973-1974
growth began         early March       -----
floral buds formed   mid-March       mid-March
flowers opened       early April     early April
seed ripened         early May       mid-May
growth stopped       early June      early July

Related categories for Species: Poa cusickii | Cusick's Bluegrass