Flora of North America species comparison

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.)

Variety zionense grows primarily in hanging gardens of north-central Arizona, southwestern Utah, in scattered, disjunct populations on the Colorado Plateau, and on the southern edge of the Uinta Mountains, Utah. In Colorado, var. zionense is known only from hanging gardens in Moffat County (S. O’Kane 3171, CS). The pollen sacs are basically maroon and fade to yellowish apically, unlike those of var. pulchellum which, in this area, has only maroon pollen sacs. The Uinta Mountains populations, segregated as subvar. huberi S. L. Welsh, occur at 2200 to 2400 meters; this phase has a maroon connective and a yellow filament tube. In Gray Canyon, a part of the Desolation Canyon area of Utah, both the connective and tube are yellow (N. D. Atwood and A. Evenden 24463, BRY); farther upriver at Dripping Springs, the connective and tube are maroon (N. D. Atwood and A. Evenden 24378, BRY). In Zion Canyon, the pollen sacs are purplish or at least heavily speckled with purple over yellow and the filament tube is proximally yellow and distally maroon. In White Canyon, Arizona, the tube is yellow and the connective purple (G. Rink 4829, NY). Without exception, at least the distal one-half to one-third of the pollen sac is purplish to maroon in all populations. As well, nearly all populations have minutely glandular pedicels and, often, calyces. Variation in stamen features may indicate that var. zionense, as defined here, comprises merely the ecological extremes of other variants, namely var. pulchellum and var. monanthum; the combinations of shade and continued moisture may be the only factors that promote the distinctive large leaf blades. Plants from the rim of Zion Canyon, which are small-leaved, are treated here as var. pulchellum, as are the small-leaved populations on seeping cliff-faces in Uintah County.

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