(entireleaf mountain-avens)
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Photo of Dryas integrifolia by Carl Roland
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Entireleaf mountain-avens is a mat-forming dwarf shrub like all members of its genus, with small leathery leaves below white flowers, distinguished from other species of mountain-avens by the usually toothless leaf margins.
Dryas integrifolia grows in well-drained alpine tundra and gravelly slopes, growing 3-12 cm tall from prostrate woody stems. The buds are
glandular and red-hairy. The leaves are
lanceolate, 3 times longer than broad, the base truncate or rounded, margins
entire or with a few teeth towards the base, the edges inrolled. The upper surface is dark green, the lower white-hairy. On the underside of the leaf, the midvein is typically covered in hairs; if visible it lacks
glandular hairs. Flowering stems are leafless, hairy, and bear a single flower. Flowers have eight (to ten) white petals, surrounded by a similar number of
sepals, 1-3 cm wide. The petals are broadly
ovate or
elliptic and hairy; the
sepals are narrowly triangular with wooly white hairs and many dark red
glandular hairs. Flowers have many
stamens and
pistils. The flowers develop into many single-seeded
achenes with attached feathery
styles. The
styles are initially twisted together before opening into a dandelion-like head. Entireleaf mountain-avens is easy to distinguish from other species of the genus
Dryas because of its smooth-edged,
lanceolate leaves.
Dryas integrifolia is a perennial species, with semi-evergreen leaves. It flowers early in the summer, the
stamens maturing before the
pistils (
Phillip et al. 1990).
D. integrifolia is
monoecious with bisexual flowers that attract insects. In a large study in Greenland, seed set in self-pollinated flowers was found to be similar to those out-crossed or left undisturbed, 60-70% in all cases (
Philipp et al. 1990). Only flowers that were emasculated and isolated had reduced fruit set, indicating
D. integrifolia is self-compatible. The pollen to ovule ratio of
D. integrifolia is fairly high, typically an indicator of an out-crossing breeding system, and the flowers are visited by a number of insects. Some of its flowers are heliotropic, aligned with the sun at noon, a habit which increases the solar radiation (and therefore heat) on the developing fruits, and results in heavier seeds (
Krannitz 1996). The
pistils develop into
achenes, each one attached to a long, feathery
style, which catches the wind and carries the seed far from the parent plant.
D. integrifolia also grows clonally, forming large mats.
Dryas integrifolia is an amphi-Beringian species that occurs primarily in North America, where it is broadly distributed, but reaches adjacent areas of Chukotka across the Bering Sea from Alaska. This species ranges from Alaska to Greenland, south to Newfoundland and northern Quebec, through the Canadian Arctic Archipelago and south along the Rockies to British Columbia and Alberta. In Alaska, the species occurs on the North Slope and in suitable habitat throughout alpine areas, its western limit being the Alaska Peninsula. In Denali, Dryas integrifolia occurs commonly in the mountains north of the Alaska range crest and in the upper Chulitna River drainage to the south.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Entireleaf mountain avens is equally common on most slopes, slightly more frequent on very steep slopes (inclines above 28 degrees). It occurs in the alpine and subalpine, particularly elevations of 900-1100 meters. This species seems is less frequent on southern aspects, and most common on east or west-facing slopes. Though common in the park, it is not one of the most abundant species of Dryas.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Well-drained dry to somewhat moist sites.
