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

GENERAL BOTANICAL CHARACTERISTICS:

Crested wheatgrass is a cool-season, medium-height, exotic perennial bunchgrass. The plant is drought- and cold-resistant and long-lived, enabling it to establish in recognizable monocultures [105]. Crested wheatgrass culms are 10 to 40 inches (25-100 cm) tall [30] and widely spaced. The deep, finely branched fibrous roots of crested wheatgrass penetrate to a maximum depth of 8 feet (2.4 m), with most roots extending to a depth of 3.3 feet (1 m) [80]. Crested wheatgrass is common in the Northern Great Plains and in Canada [105], while desert wheatgrass is more common throughout the western United States. Desert wheatgrass is tall and coarse, while crested wheatgrass is smaller, leafier, and has broader seedheads. Crested wheatgrass is a diploid species, which differentiates it genetically from desert wheatgrass, a tetraploid [34].

Crested wheatgrass remains productive for more than 30 years. Stand mortality is virtually unknown, except in cases of extreme drought during critical phenological stages [51].

RAUNKIAER LIFE FORM:

Hemicryptophyte

REGENERATION PROCESSES:

Crested wheatgrass reproduces by seed or vegetatively and is self-sterile [35]. Crested wheatgrass seedlings are very hardy, vigorous, and easily established [67]. The seeds of crested wheatgrass germinate well throughout a range of temperatures [7], allowing the plant to spread rapidly [62]. Crested wheatgrass produces tillers, and its ability to spread vegetatively contributes to its presence at higher elevations, where the growing season may not be long enough each year to produce seed [51]. However, in drier habitats, the ability of rhizomatous native grasses to propagate without setting seed allows them to compete well with crested wheatgrass [85]. Crested wheatgrass is able to emerge from a relatively deep soil depth, which allows it to escape the more extreme environmental soil conditions closer to the surface. Crested wheatgrass shoots have long, numerous, and quick-growing roots, which may explain strong seedling establishment [67].

SITE CHARACTERISTICS:

Crested wheatgrass is tolerant of very cold and very dry conditions, typical of both its native habitat in Russia and some areas of the northern Great Plains [12,24, 66,103]. It grows best on medium-textured soils, from sandy loams to clay loams. Crested wheatgrass does not grow well in loose sandy soils, heavy clays, or saline soils [84,91]. Crusted soils impede crested wheatgrass seedling emergence [67].

Crested wheatgrass thrives at around 12 to 16 inches (305-406 mm) of precipitation and competes poorly with other grasses on moister sites [24,63,105]. In Utah, crested wheatgrass appears on sites with precipitation of at least 12 inches (300 mm) [115].

Crested wheatgrass appears in the following elevations:

State     Elevation, in feet (m)
WY        above 6,000 (1800) [13]
UT        2,730 to 9,040 (910-2740) [115]
CA        1,900 to 5,000 (600-1500) [54]
CO        5,000 (1,500) [52]

SUCCESSIONAL STATUS:

Due to the broad range of habitat types in which crested wheatgrass has been planted, reports conflict on the plant's persistence. Crested wheatgrass is persistent and allows little establishment of native species in some habitat types, especially in arid and heavily grazed areas [2]. A crested wheatgrass community in southeastern Alberta was determined to be over 40 years old, and in central North Dakota, northern Arizona, and southern Idaho, stands over 30 years old have been identified [68].

However, shrub re-invasion of crested wheatgrass occurs in the Intermountain West, especially in wet years. Unkilled mature sagebrush in the seeded area is a source of reinvasion [87]. In the arid shadscale (Atriplex spp.) zone of Utah and Nevada, stands of crested wheatgrass appear to be shorter lived, with an estimated 10-year life span [18]. Anderson and Marlette [4] point out that the age of these stands may reflect the available data, and not the potential for stand longevity. They suggest that crested wheatgrass may inhibit or preclude the re-establishment of native species on disturbed sites and may become the dominant species.

In laboratory trials, volatile substances and aqueous extracts from the leaves of big sagebrush exhibited allelopathic, inhibitory effects on germination and shoot and radicle growth of crested wheatgrass seedlings [50]. However, simultaneous establishment of both sagebrush and crested wheatgrass favors the grass [17].

Crested wheatgrass has limited ability to invade undisturbed shortgrass communities in northeastern Colorado and was an unimportant component in the recovery, after 53 years, of old fields [28].

SEASONAL DEVELOPMENT:

Crested wheatgrass greens up 2 to 4 weeks earlier than native bunchgrass species. It goes dormant in the summer, but if soil moisture is available, it will grow again in the fall. In Alberta, at the northern end of the plant's range, seasonal development was as follows [85]:

stage of maturity     sample date
preflower              5/10
heading                6/8
flowering              6/29
seed ripe              7/30
seed shed             10/21

Related categories for SPECIES: Agropyron cristatum | Crested Wheatgrass