PLANT: Shrub 1-4 m tall, openly branched, sparingly armed, the branches rigid, densely pubescent when young, the bark dark gray or brown to reddish brown.

LEAVES: spatulate to obovate, 5-25 mm long, 3-8 mm wide, obtuse or rounded at the apex, rarely acute, densely glandular-pubescent, attenuate to a petiole 3-5 mm long, densely glandularpuberulent.

FLOWERS: pendant, single or in groups of 2-3 (Fig. 2A); pedicels 3-6 mm long; calyx tubular-campanulate, 2.5-6 mm long, densely pubescent; lobes 5, 1/4 to 1/2 the length of the tube, equal, or the calyx irregularly lobed and more or less two-lipped, then some lobes as long as the tube; corolla funnelform, slightly narrowed just above ovary, 7-14 mm long, whitish, greenish, or tinged with purple and brown, glabrous externally; lobes 5, broadly ovate or obovate, pale lavender, spreading, 1-2 mm long, with sparsely ciliolate or glabrous edges; stamens 5, subequa1, from slightly to 2-3 mm exserted from the corolla-tube; filaments adnate to a point between a little below the middle of the corolla-tube, densely pilose on the 20 CANOTIA Vol. 5 (1) 2009 lower 2/3 of their free portion; corolla-tube densely hairy from the base to the point of adnation of the filaments, then less densely hairy up to the point where the filaments cease to be hairy; anthers 1-2 mm long; style usually slightly shorter than the stamens, and only slightly exserted but sometimes long-exserted.

NOTES: Upper Sonoran Desert in AZ, in washes and on mountain slopes: Coconino, Gila, Graham, La Paz, Maricopa, Mohave, Pima, Pinal, Santa Cruz, Yavapai cos. (Fig. 1D); 300-1400 m (1000-4600 ft); Jan-Apr; s to Baja C. Sur, Son., and Sin., Mex. The distinction between Lycium exsertum and L. fremontii is usually not difficult in living plants but often so with dried specimens as habitat and flower color are important. The species are compared directly in lead 9 of the key.

REFERENCES: Windham, M.D. And G. Yatskievych. 2009. Vascular Plants of Arizona: Isoëtaceae. CANOTIA 5 (1): 27-29, 2009.

Common Name: Arizona desert-thorn

Duration: Perennial

Nativity: Native

Lifeform: Shrub

General: Openly branched, sparingly armed shrub, 1-4 m tall; branches rigid, dark gray or brown to reddish brown; young twigs densely pubescent.

Leaves: Alternate, on petioles 3-5 mm long; leaves often clustered; blades spatulate to obovate, 3-7 mm wide by 5-20 mm long, obtuse or rounded at apex, densely glandular-puberulent.

Flowers: Solitary or in clusters of 2-3 in leaf axils, pendant on 3-6 mm pedicels; calyx narrowly bell-shaped, 3-6 mm long, densely glandular-puberulent, topped with 5 lobes, these 1 mm long, deltoid, and acute; corolla whitish, greenish, or tinged with purple and brown, funnel-shaped, slightly narrowed just above ovary, 8-12 mm long, glabrous on the outside, topped with 5 lobes, these broadly ovate or obovate, spreading, 2 mm long, and pale lavender with sparsely ciliolate or glabrous edges; filaments fused to inside of corolla tube about halfway up the corolla, densely pilose above the fused portion; stamens usually exserted.

Fruits: Ovoid berry, 6-8 mm long, red, fleshy, 20-35 seeded.

Ecology: Found along washes and flats below 4,000 ft (1219 m); flowers year-round, mostly January-March.

Distribution: s AZ, se CA, and nw MEX

Notes: Told apart by its densely pubescent twigs, densely glandular-pubescent leaves, stamens exserted 2-5 mm, and pendulous flowers. Is separated from the common and widespread L. andersonii by its larger size and many hairy parts (L. andersonii is almost wholly glabrous). It is most similar to L. fremontii and is best distinguished by the flowers, which are mainly dark purple and erect in that species, with glabrous or lightly pubescent filaments. These differences are much easier to see in the fresh material rather than dried specimens, which often lose their color. L. fremontii also tends to grow in low saline habitats, while L. exsertum is found in upland habitats.

Ethnobotany: Berries used for food, eaten fresh, ground, dried, made into mush, and even boiled.

Etymology: Lycium is from Greek name Lykion used to describe a thorny tree or shrub, exsertum likely refers to the exserted (protruding) stamens.

Synonyms: None

Editor: SBuckley 2010, AHazelton 2016