• GENERAL BOTANICAL CHARACTERISTICS
• RAUNKIAER LIFE FORM
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS
• SEASONAL DEVELOPMENT

GENERAL BOTANICAL CHARACTERISTICS:

Bluebunch wheatgrass is a native, cool-season, perennial grass with densely tufted culms, 12-30 in. (30-100 cm) tall, erect or nearly so [225]. Bluebunch wheatgrass is capable of an unusually broad range of osmoregulation, which helps the plant survive under a range of moisture conditions [93]. Bluebunch wheatgrass is among the most drought-resistant native bunchgrasses [126].

Maximum rooting depth of bluebunch wheatgrass in Washington is 4.6 feet (1.4 m) [61] and can reach 6.6 feet (2 m) [131]. Roots of mature bluebunch wheatgrass generally are deeper in the soil profile than those of cheatgrass, allowing the plant to acquire soil moisture much better below 1.6 feet (0.5 m) [68]. Vesicular-arbuscular mycorrhizae (VAM) of the genus Glomus are found on the roots of bluebunch wheatgrass [60]. Bluebunch wheatgrass occasionally produces short rhizomes in more mesic environments (above 17.7 inches (450 mm) annual precipitation) [25,72,81,84,88,166].

Root characteristics of beardless bluebunch wheatgrass in Colorado are as follows [44]:

Characteristic                 inches           cm
Maximum root depth              52              132
Maximum lateral spread          20               50
Zone of root concentration     269(in2)       1,737(cm2)
Depth of root concentration     18               46
Diameter of root concentration  16               41

RAUNKIAER LIFE FORM:

Hemicryptophyte

REGENERATION PROCESSES:

Bluebunch wheatgrass is highly self-sterile [20]. The plants do not flower and produce seeds every year [166,177,201]. Seedling establishment tends to be generally poor [13,40,99,131]; bluebunch wheatgrass usually reproduces by tillers [166]. Bluebunch wheatgrass is a facultative autumn-emerging species; seeds will germinate in the fall given appropriate climatic conditions [8]. If appropriate conditions are not present, the seed will either remain dormant or go dormant until winter or spring. In southeastern Montana, bluebunch wheatgrass produces relatively few large seeds. The seeds are able to germinate under a wide range of temperatures, a characteristic that allows the plant to dominate in an inconsistent environment [101]. Optimum germination of bluebunch wheatgrass seeds occurs at 48°/68°, 48°/77°, 48°/86°, 68°/77°, and 68°/86° Fahrenheit (15°/20°, 15°/25°, 15°/30°, 20°/25°, and 20°/30°C), where the first number represents 16 hours of cold, and the second, 8 hours of warm temperature [169]. Germination is inhibited by litter of twisted moss (Tortula ruralis) [23].

SITE CHARACTERISTICS:

Bluebunch wheatgrass requires excellent drainage and mostly full sun [136]. The plant grows under a wide range of precipitation regimes [93], from 6 to 35 inches (150-890 mm), although it grows best above 13.7 inches (350 mm) [126]. In the Intermountain West, bluebunch wheatgrass thrives with less than 17 inches (432 mm) annual precipitation [217]. It grows from 300 to 5,000 feet (91-1524 m), on both northern and southern slopes, depending on location. In Utah, bluebunch wheatgrass dominates from 4,492 to 9,508 feet (1,370-2900 m), and in Arizona, from 4,500 to 7,500 feet (1373-2286 m) [155]. Bluebunch wheatgrass needs at least 10 inches (25 cm) of moderately coarse, loam soils, and is intolerant of excessive salts or soil moisture [63,99,126,213]. In the Columbia Basin region of northeastern Oregon, bluebunch wheatgrass dominates on moderately deep silt loams, on northern exposures up to 30 to 40% slope [9]. In Nevada, bluebunch wheatgrass appears on shallow, stony soils, with a moderate to strongly developed B horizon high in clay [98]. Bluebunch wheatgrass is adapted to mountain brush types in the Intermountain West with southwestern, dry and sunny exposures, in both open (Gambel oak (Quercus gambelii)-Saskatoon serviceberry) and closed (Gambel oak-bigtooth maple (Acer grandidentatum)) communities [217]. In the Blackfoot River Valley, Montana, bluebunch wheatgrass grows on all aspects but most frequently on southern exposures. The plant displays no significant preference for location on the hillside [42]. Bluebunch wheatgrass appears in sagebrush steppe and open woodland habitat types in California, from 2,623 to 5,410 feet (800-1650 m) [136]. In northeastern Oregon, between 2,800 and 4,000 feet, bluebunch wheatgrass appears with Sandberg bluegrass, rose (Rosa spp.), snowberry, antelope bitterbrush (Purshia tridentata), sumac (Rhus glabra), and blue elderberry (Sambucus cerulea) [10].

SUCCESSIONAL STATUS:

Bluebunch wheatgrass establishes on newly disturbed sites by tillering [71,72206,211]. A mass flowering response after fire [3,191,209] suggests that on burns, it may also establish from seed, but seedling establishment after fire or other disturbance is not documented in the literature. Bluebunch wheatgrass is also common in older, established plant communities [80,82].

SEASONAL DEVELOPMENT:

Because of bluebunch wheatgrass' extensive latitudinal and elevational range, seasonal development varies. Quinton and others [201] found bluebunch wheatgrass in British Columbia grew as early as mid-March around 1,298 feet (396 m), and by April 7th at 3,597 feet (1097 m). They report growth stopping in June at low elevations and in mid-August at higher elevations.

The seasonal development of bluebunch wheatgrass in central Utah is as follows [39]:

Growth stage             Average date
Snow off                 April 1
Growth started           April 8*
Flower stalks appear     May 23
heads showing            June 5
Heads fully out          June 14
Flowers in bloom         June 25
Seed ripe                July 17
Seed disseminating       July 23
Seed disseminated        August 6
Plant drying             July 7
Plant dried              September 4
  *sometimes plants remain green under the snow during winter, 
   so this date is difficult to determine

Related categories for SPECIES: Pseudoroegneria spicata | Bluebunch Wheatgrass