Desert Milkweed. Asclepias subulata, Milkweed Family: ( Asclepiadaceae ), Desert Milkweed. Also called: Skeleton Milkweed, Rush Milkweed, Ajamente. We wish to thank Wikipedia, the free encyclopedia for some of the information on this page. We share images and information with Wikipedia. This is a good xeriscape landscaping plant in arizona and it is considered a small to medium evergreen shrub; gray green in color, usually leafless, its stems contain a milky sap. it has short-lived linear stems about 2 inches long . Some consider the plant a succulant. Butterflies are attracted to it. Especially Monarchs. Quick Notes: Height: Evergreen succculant growing to 2 - 5 feet tall and 4 feet wide. Flowers: The flowers in clusters that are light yellow to cream in color. They turn into a mature follicle, releasing seeds on silky hairs. Flowering Time: Phoenix Arizona, April - November. Leaves: The leaves are short lived. redish in color and small. Found: Native of the USA (AZ, CA, NV). Also in the following states of Mexico; Baja California, Sonora, and Sinaloa. Hardiness: USDA Zone 9a: to -6.6 �C (20 �F) USDA Zone 9b: to -3.8 �C (25 �F) USDA Zone 10a: to -1.1 �C (30 �F) USDA Zone 10b: to 1.7 �C (35 �F) USDA Zone 11: above 4.5 �C (40 �F) Soil pH requirements: 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline) 7.9 to 8.5 (alkaline) Sun Exposure: Full Sun Some Shade Elevation: 0 - 2,400 Feet. In most places including Arizona. Has been found as high as 3,000 feet. Habitat: Lower elevations. It grows well in sand, or sandy loam. It needs good drainage and aeration. It is remarkably tolerant of alkali. Desert washes, creosote bush scrub. An ideal xeriscape landscape plant in Arizona. Miscellaneous: Maintenance: Low. Leaf Photos Taken February 19 2006. Glendale, Arizona Xeriscape Garden. Flowers April 22, 2007. Mayo Clinic Hospital, Phoenix, Arizona.