Photo © Douglass Henderson
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Primula alcalina A. Cholewa & D. Henderson

Alkali primrose

Primulaceae (Primrose family)

General Description: A perennial herb from a flat basal rosette of light green, crinkly leaves, each 1-4 cm long. Young leaves have a white mealy coating that disappears as the leaves age. The leaf blades are elliptic and gradually narrow at the base to a winged petiole. Flowering stems are leafless and range between 5-30 cm tall. The inflorescence is a tight cluster of 3-10 erect flowers terminating the leafless stem. Flowers are white with a yellow center; the petals fused into a tube for their lower half, then flaring into 5 lobes, each about 1 cm long and clearly notched at the apex. The calyx is bell-shaped, with a somewhat white mealy coating. The involucral bracts at the base of the inflorescence also have a somewhat white mealy coating.

Illustration.

Field Identification Tips: Alkali primrose is distinguished by its tight rosette of crinkly leaves, and solitary, leafless flower stalk usually around 15 cm tall terminated by a tight umbel of white flowers. The white mealy bloom covering young leaves is absent from older, mature leaves.

Photo © Robert K. Moseley
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Phenology: Flowers in May and early June. Fruits develop through June, July, and August. The basal rosettes, with their distinctive wavy leaves remain green at least until the end of August. The leaves and flowering stem enlarge over the growing season, and by the time the capsules are ripe, may be several times their length compared to when first flowering.

Similar Species: Primula incana (Jones' primrose) is a widespread species rare in Idaho. It occurs in wetland habitats, but differs from alkali primrose in having lavender-colored flowers and mature leaves covered with a white, mealy powder. There are also technical differences in the flowers to distinguish the occasional white (albino) Jones' primrose plant that may be found. Other Primula species known for Idaho do not occur in wet, alkaline meadow habitats. The basal rosettes of alkali primrose and another member of the primrose family, Dodecatheon pulchellum (few-flowered shooting star), are similar in size and shape. However, the Dodecatheon leaves are not white-mealy at any stage, nor do they have crenulate margins.

Photo © Robert K. Moseley
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Habitat: Alkali primrose occurs in wet, spring-fed, alkaline, intermontane valley meadow systems. The alluvial soils are fine-textured, light-colored, and derived from predominantly calcareous outwash. Plants occur in the lowest topographic position in the meadows, where the subirrigated soil is saturated throughout the growing season. Plants are found on low, relatively level benches immediately adjacent to creeks and spring heads, as well as on low benches with hummocky microtopography, where plants are restricted to the tops and sides of the hummocks. Alkali primrose is not known from creeks having large seasonal or annual flows, or channel scouring from floods. Graminoids dominate the wet meadow habitats supporting alkali primrose, including Eleocharis pauciflora, Carex scirpoidea, C. simulata, Kobresia simpliciuscula, and Juncus balticus. Associated forbs are diverse, but have relatively low cover, and include Dodecatheon pulchellum, Triglochin maritimum, and Thalictrum alpinum. Hummocks are sometimes shared with shrubs such as Betula glandulosa, Potentilla fruticosa, and several Salix species.

Global Distribution: Narrowly endemic to east-central Idaho and immediately adjacent southwestern Montana.

Idaho Distribution: Known from a series of wet, spring-fed, alkaline meadows in the large intermontane valleys of east-central Idaho, in Lemhi, Butte, and Custer counties.

References:

Cholewa, A. F., and D. M. Henderson. 1984. Primula alcalina (Primulaceae): a new species from Idaho. Brittonia 36(1): 59-62.

Kelso, S. 1991. Taxonomy of Primula sects. Aleuritia and Armerina in North America. Rhodora 93(873): 67-99.

Moseley, R. K. 1989. Report on the conservation status of Primula alcalina, a proposed candidate species. Idaho Department of Fish and Game, Conservation Data Center, Boise, ID. 32 pp. plus appendices.