Asclepias ruthiae
Asclepias ruthiae is a species of flowering plant in the family Apocynaceae. It is endemic to Utah in the western United States, where it grows in desert and shrubland habitats.
Taxonomy
The species was first described by botanist Bassett Maguire in 1941 from material collected in the San Rafael Swell of Utah. It has historically been treated as a variety or subspecies of Asclepias uncialis, but is currently accepted as a distinct species.
Description
Asclepias ruthiae is a perennial herb with multiple stems arising from a caudex. The stems are suberect and reach approximately in height. Leaves are broadly ovate, long, with a pubescent surface and short petioles.
The inflorescences are small, umbel-like clusters bearing 2–7 flowers. The flowers have a pale grayish-violet corolla with reflexed lobes and a distinctive corona structure. Fruits are erect, curved follicles measuring up to in length.
The species is part of a complex including Asclepias brachystephana, Asclepias uncialis, and Asclepias cutleri, but differs in its broader leaves and shorter corona hood lobules.
Distribution and habitat
The species is restricted to central Utah, particularly the San Rafael Swell region. It occurs in desert shrublands, including saltbush communities and pinyon-juniper woodlands, and is sometimes found along drainages.
Conservation
Asclepias ruthiae is ranked as G3 (vulnerable) by NatureServe. It is known from more than 24 occurrences, though overall abundance and trends are poorly understood.
Potential threats include livestock grazing and roadside maintenance activities, although their impacts have not been fully quantified. The species occurs in some protected areas, including Capitol Reef National Park and Bureau of Land Management lands in the San Rafael Swell.
References
ruthiae Category:Flora of Utah Category:Endemic flora of the United States Category:Plants described in 1941