Plant: perennial vine, Densely pilose, non-glandular, twining vines Leaves: lanceolate to ovate, the bases deeply to shallowly cordate to subsagittate, 2-9 cm long; petioles 1-5 cm long, shorter than the blades INFLORESCENCE: irregularly umbelliform to racemose, the peduncle tardily elongating to 3-4 cm. Flowers: 8-10 mm long; calyx lobes 4-6 mm long, somewhat longer than the corolla tube; corolla yellowish to white, green-veined on the lobes within, campanulate, the tube ca. 4-5 mm long, the lobes oblong, spreading-erect, about as long as the tube, hirsute to pilose outside and pilose toward the base inside; crown included within the corolla tube from which it arises and to which it is fused for ca. 1 mm, fleshy and cup-shaped, ca. 1.5 mm long on the inner surface and about equalling the base of the anther head, the rim free of the corolla for ca. 0.5 mm, undulate, the inner surface with 5 vertical ridges terminating at the rim in 5 pairs of knoblike lobes opposite the anthers; gynostegium elevated, the column ca. 2 mm high, the anther head funnel-shaped, slightly exserted from the corolla tube, the anther wings ca. 1 mm long; corpusculum 0.25 mm long, the pollinia pendulous from the translator arms, obovate, ca. 0.8 mm long with the upper 0.3 mm sterile and transparent; stigma head apically flat, depressed in the center Fruit: FOLLICLES 8-11 cm long, glabrous, prominently 5-winged Misc: Canyons and stream beds, desert mt. ranges; 900-1350 m (3000-4500 ft); Jul-Nov REFERENCES: Sundell, Eric. 1994. Asclepiadaceae. J. Ariz. - Nev. Acad. Sci. Volume 27, 169-187.

Sundell 1993, Wiggins 1964

Duration: Perennial Nativity: Native Lifeform: Vine General: Slender and twining vines, densely pilose with white hispid and spreading hairs, climbing to 2 m or more. Leaves: Opposite with internodes 3-20 cm long bearing slender petioles 1-5 cm long topped by lanceolate to ovate blades with deeply cordate bases, the blades 3-9 cm long, acute at the apex. Flowers: Axillary inflorescence racemose with 3-4 cm peduncle, 1-7 flowers, the pedicel equaling peduncles, the sepals ovate-lanceolate, 4-6 mm long, slightly longer than corolla tube, the corolla yellowish to white, campanulate, the tube 4-5 mm long with oblong lobes, about as wide in full flower, puberulent within and without, the crown fleshy, cup shaped and fused, the gynostegium is elevated with a column about 2 mm high, the anthers slightly exserted from the corolla tube, the stigma head flat on top, but slightly depressed in the middle. Fruits: Follicles 5-11 cm long, glabrous with wings 2-3 mm high, usually 4-5 and thin. Ecology: Found along streams and in canyons and stream beds from 3,000-4,500 ft (914-1372 m), flowers July-November. Distribution: Ranges across the upper Sonoran Desert and south into northern Sonora. Notes: The opposite cordate leaves, its vining habit and the non-glandular stems along with the 4-5 winged follicles are all key. Ethnobotany: Unknown Etymology: Matelea is thought to be named for the French botanist Jean Baptiste Cristophore Fusee Aublet (1720-1778), while arizonica means of or from Arizona. Synonyms: Gonolobus arizonicus, Lachnostoma arizonicum Editor: SBuckley, 2011