Plant: vine; stems pubescent in lines above the petioles

Leaves: oblong (the revolute margins often giving a linear appearance, especially in dried material), 0.6-3 cm long, 0.3-0.5 cm broad, glabrous, sparsely pubescent to glabrate on the midvein above and beneath, the margins sparsely ciliate; petioles pubescent above, 2-3 mm long

INFLORESCENCE: subsessile, umbelliform, ca. 1 cm across

Flowers: 3-4 mm long; calyx lobes ca. 2 mm long; corolla whitish to yellowish, campanulate, the tube ca. 1 mm long, the lobes narrowly ovate, 2-4 mm long, densely pilose inside, the tips recurved; crown segments distinct, 1-2 mm long, erect, linear-lanceolate, slightly surpassing the stigma-head; anther wings ca. 0.4 mm long; corpusculum 0.2 mm long, the pollinia oblanceolate, ca. 0.25 mm long; stigma head apically rounded

Fruit: FOLLICLES 3-6(-7) cm long

Misc: Rocky slopes and canyons of desert mt. ranges; 450-1350 m (1500-4500 ft); all year (mostly May-Oct)

REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.

Duration: Perennial

Nativity: Native

Lifeform: Vine

General: Slender branched vine, woody at base; the stem pubescent in lines above the petioles, 0.5-2.5 m.

Leaves: Opposite and short-petioled, the petioles 1-3 mm long, pubescent above; blades oblong with strongly revolute margins, appearing linear, 0.5-3 cm long about 5 mm broad, shining and dark green above, sparsely pubescent on midvein above and beneath, the margins sparsely ciliate.

Flowers: White, in axillary umbels; flowers 3-4 mm long; calyx lobes about 2 mm long; corolla whitish to yellowish, with 5 petals, campanulate, densely villous within; crown segments distinct, 1-2 mm long, linear-lanceolate, slight longer than stigma-head.

Fruits: Fusiform follicle 3-7 cm long, glabrous, 4-5 mm wide.

Ecology: Found on rocky slopes and in canyons from 1,500-4,500 ft (457-1372 m), flowers May-October.

Distribution: From c AZ south into Sonora, MEX.

Notes: Look for a vine with opposite leaves which are distinctive with their tightly revolute margins that make the oblong leaves look nearly linear; small white flowers with hairy petals; and milky sap. Other common milkweed vines, (Funastrum cyanchoides (Syn: Sarcostemma cyanchoides) and F. crispum) have larger, showier flowers that are not distinctively hairy.

Ethnobotany: Unknown

Etymology: Metastelma comes from the Greek meta or instead and stelma a crown, referring to the absence of a corona, while arizonica means of or from Arizona.

Synonyms: Cynanchum arizonicum, Metastelma albiflorum, Metastelma watsonianum

Editor: SBuckley 2011, AHazelton 2015