Solanum albescens (Britton) Hunz., Kurtziana 4: 137. 1967.

Knapp, Sandra, Saerkinen, Tiina & Barboza, Gloria E., 2023, A revision of the South American species of the Morelloid clade (Solanum L., Solanaceae), PhytoKeys 231, pp. 1-342 : 1

1. Solanum albescens (Britton) Hunz., Kurtziana 4: 137. 1967.

Figs 6 , 7

Poecilochroma albescens Britton, Mem. Torrey Bot. Club 4: 91. 1896. Type. Bolivia. La Paz: vic. Mapiri, 8,000 ft., Sep 1892, M. Bang 1575 (lectotype, designated by Bitter 1918, pg. 154; second step, designated here: W [acc. # 0100785 (1893-5558)]; isolectotypes: BM [BM000887671], E [E00504823], F [v0093033F], GH [00077569], K [K000590161, K000590162], M [M-0171597], MICH [MICH1109891], MO [MO-171597, acc. # 2218441], NY [00022197], PH [00020419], US [00027289, acc. # 1416199; 01014184, acc. # 98763], WU [acc. # 0120000]).

Capsicum albescens (Britton) Kuntze, Revis. Gen. Pl. 3[3]: 218. 1898 [28 Sep 1898]. Type. Based on Poecilochroma albescens Britton.

Solanocharis albescens (Britton) Bitter, Repert. Spec. Nov. Regni Veg. 15: 153. 1918. Type. Based on Poecilochroma albescens Britton.

Type.

Based on Poecilochroma albescens Britton.

Description.

Straggling shrublet to 0.5 m high, the branches often rooting where in contact with the soil, woody at the base. Stems terete, densely pubescent with eglandular 4-5-celled simple uniseriate trichomes ca. 0.5 mm long, these antrorse, crisped and curly at the tips, the basal cell enlarged; new growth sparsely pubescent with eglandular simple uniseriate 4-5-celled trichomes ca. 0.5 mm long along the veins and margins, these curled at the tips like those of the stem; bark of older stems whitish yellow, glabrescent, somewhat corky and peeling. Sympodial units plurifoliate, the leaves not geminate. Leaves simple, the blades 1-4 cm long, 0.4-1.9 cm wide, elliptic, widest at the middle, thick and fleshy or somewhat rubbery-coriaceous, discolorous and paler beneath; adaxial surfaces glabrous, with a few simple uniseriate trichomes along the sunken midrib; abaxial surfaces glabrous or with a few simple uniseriate trichomes scattered on veins and lamina; principal veins 3-4 pairs, sunken or obscure adaxially, drying yellowish; base acute; margins entire, slightly revolute and ciliate with simple uniseriate trichomes ca. 0.5 mm long; apex acute, the tip sometimes slightly rounded; petioles 0.1-0.3 cm long, glabrous or with a few scattered simple uniseriate trichomes adaxially. Inflorescences terminal or opposite the leaves, unbranched, 0.5-2 cm long, with 2-5 flowers clustered at the tips, glabrous to sparsely pubescent in the lower half (peduncle) with simple uniseriate 4-5-celled curly trichomes like those of the stems; peduncle 0.4-0.5 cm long; pedicels 1.5-2 cm long, ca. 0.5 mm in diameter at the base, ca. 1 mm in diameter at the apex, filiform and spreading or drooping, glabrous, articulated at the base leaving a tiny sleeve or peg ca. 0.5 mm long; pedicel scars 1-2 mm apart in the distal part of the inflorescence. Buds ellipsoid, the corolla strongly exserted from the calyx before anthesis. Flowers 5-merous, cosexual (hermaphroditic). Calyx tube 1.5-2 mm long, cup-shaped, the lobes 1-1.5 mm long, ca. 1.5 mm wide, deltate with a strongly swollen tip, this fleshy(?) tip drying dark and with a few simple uniseriate trichomes 0.1-0.2 m long at the very apex. Corolla 3-4 cm in diameter, 1.5-1.8 cm long, white, campanulate, lobed 1/8-1/6 of the way to the base, the lobes 3-5 mm long, 5-5.5 mm wide, the lobes not spreading, slightly curved inwards, adaxially glabrous, abaxially densely papillate, the papillae denser along the tips and margins. Stamens equal; filament tube minute; free portion of the filaments 1-1.5 mm long, glabrous; anthers 2.5-3.2 mm long, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age. Ovary conical, glabrous; style 7-7.5 mm long, straight, exserted beyond the anther cone, glabrous, fully included within the campanulate corolla; stigma minute, merely a widening of the style tip, the surfaces minutely papillate. Fruit and seeds not known. Chromosome number not known.

Distribution

(Fig. 8 ). Solanum albescens is endemic to the Bolivian Andes (Depts. Cochabamba, La Paz).

Ecology and habitat.

Solanum albescens is a plant of cloud forests and grassy areas near treeline on steep slopes, from 2,700 to 3,500 m elevation.

Common names and uses.

Bolivia. La Paz: kurpusa (Girault s.n.). No uses recorded.

Preliminary conservation status

( IUCN 2022). Endangered [EN - B1,2ab(ii, iv) D2]. EOO = 7,953 km2 [VU]; AOO = 20 km2 [EN]. The EOO would suggest that S. albescens should be assessed as Vulnerable, but the small number of known populations (<5) and the paucity of recent collections suggest an Endangered status based on the AOO is more realistic. Solanum albescens has not been collected within any protected area.

Discussion.

Solanum albescens is an unusual species in the Morelloid clade with large, campanulate corollas and a woody creeping habit. It was first described as a member of the genus Peocilochroma Miers ( Miers 1848) on the basis of its corolla shape ( Poecilochroma is now considered a synonym of the genus Saracha Ruiz & Pav.). Bitter (1918) later recognised it as a monospecific genus Solanocharis Bitter unrelated to Poecilochroma , but he did not suggest relationships due to lack of mature fruit on the few specimens he examined. Hunziker (1967) recognised it as a species of Solanum based on the morphology of the androecium and inflorescence, and considered it related to S. macbridei Hunz. & Lallana (a member of the Dulcamaroid clade with similar pedicel sleeves, campanulate corollas and small, leathery leaves; Knapp 2013). Child (1994) erected Solanum section Solanocharis , to include S. albescens , S. rheithrocharis Bitter (here considered a synonym of S. leptocaulon ), S. leptocaulon and S. poecilochromifolium Rusby (as ' poecilochromophyllum ', here considered a synonym of S. gonocladum ) based on their habit as decumbent shrubs with somewhat campanulate corollas.

Solanum albescens is morphologically similar to S. leptocaulon , sharing with it a decumbent habit, high elevation distribution and campanulate flowers. The species differ in leaf texture (those of S. albescens are much more leathery/coriaceous than those of S. leptocaulon ), pubescence ( S. albescens has curling trichomes confined to the stems or only on leaf margins, while the leaves of S. leptocaulon are often pubescent on the lamina and the trichomes are stiff and usually antrorse) and flower size (1.5-2 cm long in S. albescens and 1-1.2 cm long in S. leptocaulon ). Although the anthers of both species are similar in size (2.5-3 mm long) the relative size of the anthers is strikingly smaller in S. albescens due to the much larger corolla. The tips of the calyx lobes in S. albescens appear to be fleshy and somewhat swollen but this needs confirmation with field examination.

In some publications and databases, the authorship of Poecilochroma albescens is given as Britton ex Rusby because it was published in an enumeration of plants collected by Miguel Bang that was authored by H.H. Rusby ( Rusby 1896). In the protologue the name Poecilochroma albescens was explicitly attributed to N.L. Britton, and we are following the International Plant Names Index (https://ipni.org/n/204701-2) in attributing both name and description to Britton. In the protologue of Poecilochroma albescens ( Rusby 1896) two collections were cited: Bang 1575 and Rusby 2563, without citing a specific herbarium. In describing his new genus Solanocharis Bitter, Georg Bitter (1918) cited only Bang 1575 as type, thus effectively lectotypifying the name, but he cited four herbaria ("herb. Berol., Monac., Vindob., Vratisl."). We narrow this here and select the sheet of Bang 1575 held in Vienna (W) cited by Bitter (1918) as “Vindob.” as the second step lectotype; it is the best preserved of the duplicates cited by Bitter that we have seen.

Figures

Figure 6. Solanum albescens A flowering branch B branch with flower buds C detail of abaxial leaf surface D detail of adaxial leaf surface E bud F dissected flower (A-F Brooke 6905). Illustration by R. Wise.

Figure 7. Solanum albescens A habit B habit with flower buds C habit with flowers at anthesis (A-C Brooke 6905 [BM 000887669]). Reproduced with permission of the Trustees of the Natural History Museum.

Figure 8. Distribution map of Solanum albescens.