(largeflowered wintergreen)
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Photo of Pyrola grandiflora by Carl Roland
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Large-flowered pyrola is an evergreen herb in the wintergreen family (Pyrolaceae), which grows in the forest understory, ranging into meadows and tundra in the mountains. Large-flowered pyrola is distinguished by its large (relative to other wintergreen species) white flowers. Plants grow 5-20 cm tall from a
rhizome. Large-flowered pyrola has only basal leaves that are broadly
ovate to rounded, with a blunt, round or
cordate base, and
petioles longer than the blade. Leaves are leathery with slightly
crenate margins. The
inflorescence is unbranched with 4-12 flowers spiraled around a reddish stem. The
perfect flowers have five large (6-10 mm long by 4-6 mm wide) white petals, often pinkish at the base. The flowers are open, flat to cup-shaped, the five petals spread apart. The petals are rounded with very finely
serrate margins. The reddish
sepals are narrowly triangular with membranous margins. The ten
stamens have a yellow
anther-covering and white
filaments. The
style is long-exserted from the flower and curved, with a ring below the
stigma lobes. Flowers face out and slightly downwards. Fruits are globose
capsules, 3-4 mm x 4-6 mm, containing many tiny seeds. Largeflowered pyrola can be distinguished from other members of its genus by its relatively large white flowers.
Pyrola grandiflora is a perennial with evergreen leaves, which turn a dark red color from the fall until early spring. It typically flowers in mid-summer.
Flowers are bisexual, and pollinated by bees. The
anthers have two pores at the tip, which release pollen when vibrated by bees at a certain frequency. Self-fertilization is also possible, but has not been tested in field studies. When pollinated, flowers develop into reddish
capsules, which look like flattened globes with the
style still attached. The
capsules split from the base, releasing ca. 1000 seeds to be dispersed by gravity and water. Plants also spread vegetatively by
rhizomes.
Pyrola grandiflora is a circumpolar species that occurs across the northern half of North America: east from Alaska to Greenland Quebec and Labrador, including all the Canadian provinces except New Brunswick, Nova Scotia and Newfoundland. Pyrola grandiflora occurs across Alaska except for the Alaska Peninsula and Aleutian Islands and the southeast panhandle. In Denali, the species is most common in the northeastern foothills and floodplains of the park, but ranges widely in suitable habitat throughout, including both on sides of the Alaska Range crest.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
This species has a bimodal elevational distribution: it is most frequent at 900-1100 meters, followed by 300-500 meters. This split probably reflects its preferences for different habitats, growing in both forests (low elevation) and moist tundra (high elevation). Additionally, within Denali, arctic wintergreen occurs is common on steep slopes (20-28 degrees) and low inclines (<4 degrees). Of those specimens on steeper inclines, they are more likely to be found on northern aspects.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Wide-ranging; somewhat wet to dry sites.
