Welsh's milkweed, Asclepias welshii
"This species is known to occur only in the Coral Pink Sand Dunes and in the Sand Hills 8 miles to the northeast of the Coral Pink Sand Dunes, both in Kane County, Utah. In the Coral Pink Sand Dunes, about 6,906 plants occur on lands administered by the Bureau of Land Management. An estimated 4,606 plants are thought to occur on State of Utah land in the Coral Pink Sand Dunes State Park, while about 506 plants are estimated to grow in the Sand Hills northeast of the Coral Pink Sand Dunes. Altogether, the total population of this species is thought to be no more than 11,996 plants."
Continue reading the Federal Register Department of the interior Fish and Wildlife Service
130 photos of Welsh's milkweed - July 31, 2019 CPSD UT
View Welsh's milkweed observations on iNaturalist
View Welsh's milkweed plant information at Wildflower.org
View Welsh's milkweed plant information at Plants.USDA.gov
Sources: USFWS Mountain Prairie