Synonym:  Asclepias macrosperma. Asclepias involucrata.  (Milkweed)
Asclepiadaceae (Milkweed Family)

Semi-desert. Sand, canyon washes, shrublands. Spring, summer.
Hunter Canyon, Utah, May 3, 2005.

The soft green of this lovely plant is made softer by the downy hairs that cover the folded and twisting leaves.  Plants sprawl along the ground with flower clusters emerging from the ends of leaf stems.  Flowers are a greenish yellow and in the starburst sphere typical of plants in the Milkweed Family.  

In 1893 Alice Eastwood collected this species in Court House Wash in what is now Arches National Park.  She named it "macrosperma" for its large seeds.

Synonym:  Asclepias macrosperma. Asclepias involucrata.  (Milkweed)
Asclepiadaceae (Milkweed Family)

Semi-desert. Sand, canyon washes, shrublands. Spring, summer.
Hunter Canyon, Utah, May 3, 2005.

Asclepias tuberosa (Butterfly Weed)
Asclepiadaceae (Milkweed Family)

Semi-desert. Canyon washes, roadsides. Spring, summer.
Chesler Park Trail, Canyonlands National Park, Utah, June, 8, 2003.

Coming down-hill into Elephant Wash I watched expectantly for bright splashes of Butterfly Weed, and I was rewarded.  In the sands and stones below me yellow-orange flowers glowed.   

"Tuberosa" refers to swellings on the roots.

Asclepias tuberosa (Butterfly Weed)
Asclepiadaceae (Milkweed Family)

Semi-desert. Canyon washes, roadsides. Spring, summer.
Chesler Park Trail, Canyonlands National Park, Utah, June, 8, 2003.

Asclepias tuberosa (Butterfly Weed)
Asclepiadaceae (Milkweed Family)

Semi-desert. Canyon washes, roadsides. Spring, summer.
Big Spring Trail, Canyonlands National Park, Utah, September, 10, 2005.

Ripening seed pods.