Flora of North America species comparison

Variety pulchellum is the most widespread and common variant of the species. It ranges from south-eastern Alaska and western Canada, to southeastern Manitoba, to Lassen County, California, northern and eastern Arizona, New Mexico, and northern Mexico. Scattered populations are found in western North Dakota (Burke County) and in western Nebraska (Morrill County). A collection at Fort Lewis, Thurston County, Washington (D. Thysell 705, WTU), may be an introduction.

Relatively small, usually high-elevation plants in southeastern British Columbia, Idaho, western Montana, northeastern Nevada, and western Wyoming have been segregated as var. watsonii. The origin of a similar specimen, supposedly from Mount Arrowsmith on Vancouver Island (collector unknown, UBC) remains to be confirmed. In Montana and northwestern Wyoming, such plants can be easily confused with the sparsely glandular Dodecatheon conjugens, which also has transverse rugose (not smooth or longitudinally wrinkled) connectives.

Plants with leaves to 25 cm wide may be seen along the Front Range of the Rocky Mountains in Colorado and in north-central New Mexico; this phase was named Dodecatheon radicatum. Some populations from Alberta (the type location of D. pulchellum) have similar leaves. Plants with yellow pollen sacs occur in some populations on the Great Plains in Alberta, Manitoba, and Saskatchewan, gradually becoming more common eastward. A collection from the Sierra Madre, Durango, Mexico (E. W. Nelson 4780, K, US) is allied to var. pulchellum. Some populations east of the Alaska Range and in adjacent northern Yukon, here assigned to var. pulchellum, have minutely glandular calyces, pedicels, nodes, and uppermost portion of scapes. The taxonomic significance of these plants has not been determined; they may indicate some past introgression with D. frigidum.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 7 (7 in the flora).

The variation within Dodecatheon pulchellum is substantial and, for the most part, each of the entities recognized here seems distinct although nearly all break down in one or more features; most seem to have intergraded with other entities in the past. Variety pulchellum is the most widespread and remains, even as treated here, quite variable. The depauperate, often uniflorous, high-elevation form, var. watsonii, is included in var. pulchellum; there is no difference except in overall size even on the East Humboldt and Ruby mountains of northeastern Nevada, the type location of var. watsonii. Widely disjunct populations assigned to var. monanthum remain problematic. The plants of northwestern California and southwestern Oregon differ only slightly from those found elsewhere in Oregon, including the Blue Mountains, where the type of var. monanthum was obtained. The southern Utah expression, while similar morphologically, displays a biogeographic pattern that is unique. A better understanding of the variation between the western and eastern phases of var. monanthum is needed.

The coastal var. macrocarpum has consistent morphological differences and a higher ploidy level (2n = 88, 132) compared with the more inland var. pulchellum (2n = 44). Whether or not the ploidy level difference is consistent remains to be shown.

The arid forms of Dodecatheon pulchellum exhibit remarkable morphological differences that require recognition (J. L. Reveal 2005). Hanging garden plants in Utah are recognized as var. zionense, following N. H. Holmgren (2005). Some populations assigned to this variety may ultimately prove to be merely large-leaved plants of either var. pulchellum or the Utah phase of var. monanthum. Zion shootingstar may owe both its large leaves and its glandular-puberulent pedicels and calyces to hybridization with D. redolens sometime in its evolutionary past, even though the latter taxon is no longer close geographically. Variety shoshonense, usually growing in moist, alkaline meadows, is found mainly in the northern Mojave Desert and the Intermountain West. The color pattern associated with the stamens differs from most other varieties of the species, suggesting a fundamental change associated with pollination and likely a closer relationship to var. cusickii (which also has yellow pollen sacs) than to var. pulchellum.

This taxon inadvertently was named Dodecatheon puberulum (Nuttall) Nuttall three years before the establishment of Exinia pulchella. To avoid nomenclatural disruptions, the basionym D. meadia var. puberulum Nuttall has been proposed for rejection (J. L. Reveal and K. N. Gandhi 2008).

(Discussion copyrighted by Flora of North America; reprinted with permission.)