(wideleaf polargrass)
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Photo of Arctagrostis latifolia by Carl Roland
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Arctagrostis latifolia is a coarse, perennial
rhizomatous circumpolar grass, which occurs frequently and widely across Denali from the boreal lowlands to the high alpine zone in a variety of moist to wet habitats including streambanks, meadows, woodlands, early successional sites and tundra. The stems may be solitary or form loose tufts, and reach up to 1.5 meters tall. The leaves have open sheaths with rough flat blades, and are 2-15 mm wide (the species name refers to its wide leaves ('lati' for wide, 'folia' referring to leaves). The
ligules are jagged and may be suffused with red or purple at the base. Wideleaf polargrass has 1-flowered pedicillate
spikelets, with unequal
glumes that are usually shorter than the awnless
lemmas. The flowers are bisexual. The panicle may be contracted with short (up to 4 cm), crowded branches or open with long (up to 27 cm) branches. The
spikelets are 3-6.5 mm long, the
paleas are nearly equal to the
lemmas, and the
anthers are 1.5-3 mm long. Fruits are single-seeded, indehiscent and dry. This species is the only
Arctagrostis in the park. It is the only very common grass species with wide leaves, and awnless, single-flowered
spikelets.
Arctagrostis latifolia is perennial and typically flowers in mid to late summer depending local site conditions.
Wideleaf polargrass is
monoecious with bisexual florets. Flowers are wind pollinated. Seeds are wind and gravity dispersed. Plants also spread extensively via their
rhizomes. In Alaska, this species is mainly made up of two chromosome races: one octoploid (8 sets of chromosomes) and one tetraploid (4 sets of chromosomes). Hexaploid (6 sets of chromosomes) hybrids also occur, but are not as common. Tetraploids appear to be more abundant, predominately found at lower elevations, with octoploids dominant in uplands (
Mitchell 1992).
The nematode
Anguina agrostis infects
spikelets and causes the ovaries to enlarge and become dark purple (Mulvey 1963 in
Aiken et al. 2003).
Grizzly bears and caribou have been observed grazing on wideleaf polargrass (Kershaw 1987, Cody 1965 in Walkup 1991). It has a high nutritional value, with crude protein of 17.8% to 19.7% (Klebesade 1969 in Walkup 1991).
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Arctagrostis latifolia is a circumpolar, arctic-alpine species occurring in Norway, the Russian Far East, Siberia, Greenland, Canada and very widely in Alaska. Indeed, wideleaf polargrass is one of the most common and widespread grass species in Denali, occurring in widely in muskeg, meadows, tundra, along rivers and in shrub-dominated areas.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Wideleaf polargrass occurs at 200-1500 m in Denali, with the greatest frequency over 500 m with the average around 1000 m. It doesn't show a strong preference for aspect, appearing with similar frequency in all aspect classes. This species occurs fairly equally at all inclines except for steep slopes (>28 degrees) in which it occurs in less than 15% of all plots. The average slope where it is found is 14 degrees, indicating a tendency to occur on moderate inclines.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Arctagrostis latifolia Throughout its range it is known to occur in a wide range of habitats in rocks, gravel, sand, silt, clay, till, moss and peat and to be calcareous (
Aiken et al. 2003).
Moist to wet sites, very wide ranging.