Lycium

Shrubs, glabrous or hairy, leaves sometimes glaucous. Stems erect to prostrate, spinescent, with single (rarely) or multiple branches (often with divaricate branching). Leaves alternate, usually in fascicles (often drought-deciduous), petiolate or sessile, sometimes succulent; blade simple. Inflorescences axillary, fasciculate or solitary flowers. Flowers bisexual or unisexual, 4–5(–6)-merous, radially symmetric or calyx occasionally ± bilateral; calyx cupulate, tubular, or campanulate, sometimes accrescent in fruit; corolla white, greenish, yellowish, or lavender to deep purple lobes sometimes white with purple veins, tubular, funnelform, campanulate, or campanulate-rotate, lobes spreading or reflexed; stamens inserted at or proximal to midpoint of corolla tube, equal or unequal; anthers dorsifixed, ovate, dehiscing by longitudinal slits; ovary 2-carpellate; style filiform; stigma slightly 2-lobed. Fruits berries, juicy, occasionally hardened or drupaceous, globose to ovoid, rarely with constrictions (L. cooperi, L. macrodon, and L. puberulum). Seeds discoid to auriform, flattened. x = 12.

Distribution

North America, Mexico, West Indies, South America, Eurasia, Africa, Atlantic Islands, Indian Ocean Islands, Pacific Islands, Australia.

Discussion

Species ca. 90 (18 in the flora).

Species of Lycium typically inhabit subtropical regions, often growing in desert, coastal, or saline environments. Some species can spread vegetatively via root suckering; plants have also been known to sprout from roots. Most species of Lycium are hermaphroditic; some are gynodioecious or dioecious. At least two species, L. californicum and L. carolinianum, are polymorphic for sexual strategy, having either hermaphroditic or dimorphic (gynodioecious or functionally dioecious) populations. Most species are diploid; some are polyploid. Polyploidy is positively correlated with sexual dimorphism.

Lycium appears to have evolved in South America, with subsequent dispersal to North America and a single long-distance dispersal event to the Old World. Grabowskia Schlechtendal and Phrodus Miers were formerly treated as separate genera; they have been transferred to Lycium.

Selected References

None.

Lower Taxa

Lycium andersonii, Lycium barbarum, Lycium berlandieri, Lycium brevipes, Lycium californicum, Lycium carolinianum, Lycium chinense, Lycium cooperi, Lycium exsertum, Lycium ferocissimum, Lycium fremontii, Lycium macrodon, Lycium pallidum, Lycium parishii, Lycium puberulum, Lycium shockleyi, Lycium texanum, Lycium torreyi

Key

1	Berries not fleshy, green to yellow, orange, or brown, seeds 2–10.	> 2
2	Berries not constricted; flowers 4(–5)-merous; plants 0.3–0.6 m, bark pale tan to white.	Lycium shockleyi
2	Berries constricted; flowers (4–)5-merous; plants 0.6–3 m, bark usually dark brown, sometimes reddish, purple, or black.	> 3
3	Berries constricted at or distal to middle; calyx lobe lengths 0.5–1 times tube; leaf surfaces usually densely glandular-pubescent, not glaucous.	Lycium cooperi
3	Berries constricted proximal to middle, calyx lobe lengths 1–2 times tube; leaf surfaces glabrous or pubescent, glaucous.	> 4
4	Calyx lobes linear; Sonoran Desert.	Lycium macrodon
4	Calyx lobes ovate; Chihuahuan Desert.	Lycium puberulum
1	Berries ± fleshy, red to orange to orange-yellow; seeds 2–50+.	> 5
5	Seeds 2, each enclosed by a hard layer forming a pyrene.	Lycium californicum
5	Seeds 4–50+, each not enclosed by a hard layer.	> 6
6	Leaves glaucous; corollas (8–)12–25 mm, funnelform.	Lycium pallidum
6	Leaves rarely glaucous; corollas 4–16(–20) mm, tubular, funnelform, campanulate, or campanulate-rotate.	> 7
7	Calyx cupulate (to tubular in L. torreyi).	> 8
8	Corollas narrowly tubular or narrowly tubular-funnelform.	> 9
9	Corolla lobe margins glabrous or sparsely ciliate.	Lycium andersonii
9	Corolla lobe margins densely ciliate-lanate.	Lycium torreyi
8	Corollas tubular to funnelform or campanulate-rotate.	> 10
10	Corollas campanulate-rotate; coastal or wetland areas.	Lycium carolinianum
10	Corollas tubular to funnelform; mainly desert areas.	> 11
11	Leaf surfaces glabrous.	Lycium berlandieri
11	Leaf surfaces pubescent.	Lycium texanum
7	Calyx tubular, campanulate, or tubular-campanulate.	> 12
12	Calyx tubular or tubular-campanulate, 2–10 mm.	> 13
13	Leaf surfaces glabrous; plants with bisexual flowers only.	Lycium ferocissimum
13	Leaf surfaces glandular-pubescent; plants with either pistillate flowers or bisexual flowers.	> 14
14	Corollas deep lavender to purple, 8–20 mm; stamens included or slightly exserted; saline desert flats.	Lycium fremontii
14	Corollas greenish white to lavender, 7–14 mm; stamens exserted 2–3+ mm from corolla in bisexual flowers; desert washes and bajadas.	Lycium exsertum
12	Calyx campanulate, 2–6 mm.	> 15
15	Leaf surfaces glabrous; pedicels 10–20 mm; corollas funnelform; occurring mainly near habitation.	> 16
16	Corolla lobes equaling or longer than tube; leaves subsessile.	Lycium chinense
16	Corolla lobes shorter than or equaling tube; leaves petiolate.	Lycium barbarum
15	Leaf surfaces glabrous or puberulent to densely pubescent; pedicels 1–10 mm; corollas campanulate to tubular or funnelform; not restricted to human-modified areas.	> 17
17	Leaf surfaces glabrous or puberulent; corollas lavender or white with purple markings, campanulate to tubular; berries 10 mm; coastal desert areas, including by the Salton Sea.	Lycium brevipes
17	Leaf surfaces densely pubescent; corollas pale lavender to purple, narrowly campanulate to funnelform; berries 4–7 mm; inland, along desert washes and bajadas.	Lycium parishii