Solanum wallacei (A.Gray) Parish, 1901

Knapp, Sandra, 2013, A revision of the Dulcamaroid Clade of Solanum L. (Solanaceae), PhytoKeys 22, pp. 1-432 : 312-314

45. Solanum wallacei (A.Gray) Parish , Proc. Calif. Acad. Sci. ser. 3, 2: 166. 1901 Figure 108

Solanum xanti A.Gray var. wallacei A.Gray, Proc. Amer. Acad. Arts 11: 91. 1876. Type: United States of America. California: Los Angeles County, Santa Catalina Island, W.A. Wallace s.n. (holotype: GH [GH00077433]).

Type.

Based on Solanum xanti A.Gray var. wallacei A.Gray

Description.

Shrubs or small trees 1-3(-3) m tall, often spreading to 2 m diameter ("weakly erect" fide Thorne & Everett 34931). Stems densely pubescent with transparent simple uniseriate trichomes of varying lengths, the longest ca. 3 mm long, with weak tangled tips, usually glandular with a single-celled gland, drying brownish tan ( “tawny”); new growth densely pubescent with similar simple uniseriate glandular trichomes, these glistening and glandular. Bark of older stems brownish green, somewhat glabrescent. Sympodial units plurifoliate. Leaves simple or very occasionally with two small lobes at the base, highly variable in size along a single stem, 3-11(-14) cm long, 1.6-5.5(-9) cm wide, elliptic to obovate, both surfaces densely and evenly pubescent with long simple uniseriate trichomes to 3 mm long, these usually glandular with single-celled glands on tips, the pubescence slightly denser along the veins; primary veins 7-9 pairs, drying paler than the lamina; base truncate or acute (seemingly depending on age of leaf); margins entire or slightly undulate, occasionally lobed with 1 or 2 small lobes near the base, the lobes very small; apex acute; petioles 1-2.5(-4) cm long, pubescent with simple uniseriate trichomes like the leaves and stems, never twining. Inflorescences terminal or lateral, (2-)4-10 cm long, usually branched once, occasionally more often, with 20-30 flowers, only a few open at a time, densely pubescent with transparent simple uniseriate glandular trichomes to 2.5 mm long like those of the stems; peduncle (1-)2-5 cm, flowers only borne above the lowest branching point; pedicels 1.5-2 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, slender, spreading, densely pubescent with transparent simple trichomes like those of the inflorescence axis, articulated at the base and inserted into a small sleeve 1-1.5 mm long, this obscured by the dense pubescence. Buds ellipsoid to obovoid, included in the calyx tube until just before anthesis. Flowers all perfect. Calyx tube 3-3.5 mm long, broadly cup-shaped, the lobes 3-3.5 mm long, deltate, densely pubescent like the pedicels and inflorescence axis. Corolla 3-4.5 cm in diameter, violet to purple with or without green spots at the base of the lobes, the spots usually small and not confluent, rotate, lobed <1/4 of the way to the base, the lobes 0.3-0.5 mm long, 1-1.5 mm wide, planar or slightly cupped at anthesis, apiculate, the apiculae ca. 2 mm long, the abaxial surface densely pubescent with tangled simple uniseriate eglandular trichomes along the lobe midvein and laterally, the sinuses and adaxial surfaces glabrous. Filament tube minute, the free portion of the filaments 2-3 mm, pubescent with weak simple uniseriate trichomes near the base; anthers 4.5-5 mm long, 2-2.5 mm wide, ellipsoid, loosely connivent or spreading and not touching, poricidal at the tips, the pores lengthening to slits with age. Ovary glabrous; style 10-13 mm long, minutely papillate with slender glandular papillae or trichomes in the basal half; stigma capitate, the surface minutely papillate. Fruit a globose berry, 3-4 cm in diameter, glabrous, the pericarp shiny, green, turning yellow then black when ripe; fruiting pedicels 1.5-2 cm long, ca. 1.5 mm in diameter at the base, hanging from the weight of the berry. Seeds more than 100 per berry, 1.5-2 mm long, 1-1.5 mm wide, plumpish flattened reniform, reddish brown, the surfaces minutely pitted, the cells sinuate, when mature the seed appearing silky hairy with hair-like projections of the lateral cell walls, these ca. 0.2 mm long over the entire seed surface. Chromosome number: not known.

Distribution

( Figure 100 , inset). Endemic to Santa Catalina Island (Los Angeles County) off the coast of California, from sea level to 300 m.

Ecology.

Solanum wallacei occurs in chaparral, open areas and in canyon bottoms. It was formerly more common, and is now considered threatened, partly due to herbivory from goats.

Common names.

USA. California: Greasy nightshade (Grant & Wheeler s.n.), Santa Catalina nightshade, Wallace’s nightshade (CalFlora, http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=7665).

Conservation status.

Critically Endangered (CR); EOO <100 km2 (CR) and AOO <500 km2 (EN). See Moat (2007) for explanation of measurements. Solanum wallacei is on list 1B.1 (seriously endangered in California) in the California Native Plant Society’s Inventory of Rare and Endangered Plants (http://www.rareplants.cnps.org/detail/1480.html). The main threats to this species are feral herbivores such as goats. The confusion over the correct application of the name has in part led to it not being recognised as endangered at the Federal level in the USA or on the IUCN Red List ( IUCN 2001).

Discussion.

Solanum wallacei is quantatively as well as qualitatively distinct from Solanum umbelliferum , its closest relative, although DNA sequence data do not unambiguously support a specific level difference ( George 2011). Flowers and fruits are larger, and the green spots on the corolla are smaller and often completely lacking in Solanum wallacei . Island forms of Solanum umbelliferum from the more northerly Channel Islands (sometimes recognised as Solanum clokeyi ) approach Solanum wallacei in pubescence morphology, with long simple uniseriate trichomes, but the flowers and fruit of those island populations fall within the range of the rest of the distribution of Solanum umbelliferum .

Specimens examined.

United States of America. California. Los Angeles County: Santa Catalina Island, on lower part of Middle Ranch Canyon, 7 May 1971, Davidson 1516 (UC); Santa Catalina Island, Hay Press, 19 Feb 1928, Dunkle 1709 (RSA); Santa Catalina Island, Silverado Canyon, 28 Mar 1936, Dunkle 4713 (RSA); Santa Catalina Island, along Cape Canyon Road, on E side at cliff, where creek comes up to road, 17 Mar 1997, Elvin & Crockett 377 (RSA); Santa Catalina Island, Hamilton Canyon, 10 m, 18 Mar 1931, Fosberg S-4285 (F, MO, RSA, UC, UC, US); Santa Catalina Island, Cape Canyon, 200 m, 6 May 1931, Fosberg S-4812 (POM); Santa Catalina Island, Avalon, entrance of canyon W of Golf Links, 9 Apr 1901, Grant s.n. (A); Santa Catalina Island, Echo Lake, 10 Apr 1921, Knopf 77 (F); Santa Catalina Island, White’s Landing, on hillside by mill, 50 m, 8 Mar 1941, Moran 687 (MO, RSA, US); Santa Catalina Island, road east of Avalon, 3 m, 2 Jul 1909, Pendleton & Reed 1366 (POM, UC); Santa Catalina Island, Upper White Landing Road, 381 m, 3 Mar 1973, Propst & Hoefs 14 (RSA); Santa Catalina Island, Pebbly Beach Road, 15 m, 2 Jul 1909, Reed 2819 (POM); Santa Catalina Island, SW part of the island in Cape Canyon, just above bed of canyon near roadside, 256 m, 23 Apr 1993, Ross & Takara 6937a (RSA); Santa Catalina Island, Middle Ranch Canyon near Eagle Nest Rock, 152 m, 23 Jun 1965, Thorne & Everett 34931 (BM, RSA); Santa Catalina Island, near mouth of Hamilton Canyon NW of Avalon, 23 m, 23 Jun 1965, Thorne & Everett 34995 (RSA); Santa Catalina Island, north slope of Black Jack Mountain, 1/8 mile down road to White’s Landing, 412 m, 5 Apr 1966, Thorne 35798 (RSA); Santa Catalina Island, in canyon leading to White’s Landing, E of Black Jack Mountain, 91 m, 2 Jun 1966, Thorne 36520 (GH, RSA); Santa Catalina Island, 1 mile beyond Eagle Nest Lodge, Middle Ranch Canyon, 25 May 1965, Thorne 41570 (RSA); Santa Catalina Island, Avalon, Mar 1901, Trask s.n. (E, K, MO, US); Santa Catalina Island, along the road to Renton Mine, about due west of Pebbly Beach, 304 m, 9 May 1932, Wolf 3491 (RSA, US); Santa Catalina Island, Hamilton Canyon, below turn in road, above airport, 22 m, 4 Oct 1932, Wolf 4219 (A, RSA, UC); Santa Catalina Island, about 1 mile NE of the Wrigley Mausoleum at head of Avalon Valley, 122 m, 25 Jun 1941, Wolf 10891 (RSA).

Figures

Figure 100. Distribution of Solanum umbelliferum Eschsch. and Solanum wallacei (A. Gray) Parish (inset)

Figure 108. Solanum wallacei (A. Gray) Parish. (A, C-F drawn from Moran 687 B drawn from Trask s. n., coll. May 1896 G drawn from Walker 1433). Illustration by Bobbi Angell.