Solanum umalilaense Manoko, PhytoKeys 16: 67. 2012

Saerkinen, Tiina, Poczai, Peter, Barboza, Gloria E., Weerden, Gerard M. van der, Baden, Maria & Knapp, Sandra, 2018, A revision of the Old World Black Nightshades (Morelloid clade of Solanum L., Solanaceae), PhytoKeys 106, pp. 1-223 : 1

18. Solanum umalilaense Manoko, PhytoKeys 16: 67. 2012 Figure 55

Type.

Tanzania. Mbeya: Mbeya District, Umalila Forest Reserve , ca. 7 km W of Ruanda II on road to Izumbwe , 2 km SSE of Mbogo Mtn. main peak, 9°11'S, 33°18'E, 2180 m, 14 Nov 1992. R.E. Gereau, D.K. Harder, C.J. Kayombo & M.J. Kayombo 5084 (holotype: DSM; isotypes: EA, K [K001081869], MO [MO-2293667, acc. # 4281580], NHT) .

Description.

Annual to short-lived erect perennial herbs to 0.5 m tall, erect, predominantly branching from the base. Stems spreading, ridged or winged, dark purple to green, erect, not markedly hollow; new growth puberulent with simple, spreading, uniseriate, translucent, eglandular trichomes, these 2-8-celled, 0.3-0.8 mm long; older stems glabrescent. Sympodial units difoliate, the leaves not geminate. Leaves simple, 1.8-2.8 cm long, 0.1-1.7 (-2.1) cm wide, ovate to elliptic, membranous, green to dark green above and below, without smell; adaxial and abaxial surfaces glabrous or sparsely pubescent with simple uniseriate trichomes like those on the stem mainly along veins; major veins 3-4 pairs, paler green or often purple tinged; base truncate, narrowly winged on to the petiole; margins entire; apex acuminate to acute; petioles 0.6-1.3 cm long, glabrous or sparsely pubescent with simple uniseriate trichomes like those of the stem. Inflorescences 2-6 cm long, internodal, simple or usually branched and often leafy, the flowers spaced along the rhachis, with 2-9(-20) flowers, glabrous or sparsely pubescent with simple uniseriate trichomes like those on the stem; peduncle (0.5-)1.1-4 cm long, erect, ca. 0.5 mm thick at apex, stout; pedicels 5-7(-9) mm long, ca. 0.2 mm in diameter at the base, ca. 0.5 mm in diameter at the apex, stout, pendent, articulated at the base; pedicel scars widely spaced (1-)3-8 mm apart. Buds subglobose, the corolla exserted 1/2 from the calyx tube before anthesis. Flowers 5-merous, perfect. Calyx tube 0.8-1.0 mm long, cup-shaped, the lobes equal, 0.1-0.5 mm long, 0.5-0.7 mm wide, broadly deltate with an acute tip, green or purple-tinged, glabrous or sparsely pubescent with simple uniseriate trichomes like those of the pedicels. Corolla 7-11 mm in diameter, white, margins occasionally tinged with purple, with a yellow basal star, stellate, lobed ca. 1/2 way to the base, the lobes 2.5-3.5 mm long, 2-3 mm wide, spreading or reflexed, densely papillate abaxially. Stamens equal; filament tube to 0.1 mm long; free portion of the filaments 0.5-1.0 mm long, pubescent adaxially with tangled uniseriate simple trichomes; anthers 1.8-2 mm long, 0.5-0.6 mm wide, ellipsoid, yellow, poricidal at the tips, the pores lengthening to slits with age and drying. Ovary rounded, glabrous; style 3.1-3.5(-4.2) mm long, densely pubescent with simple uniseriate trichomes 0.2-0.5 mm long in the basal 1/2-2/3, exserted 1.0-1.5 mm beyond anther cone; stigma clavate, the surface minutely papillate. Fruit a globose berry, 3-4(-5) mm in diameter, pale yellow-brown at maturity, aromatic, the pericarp soft, matte, not transparent; fruiting pedicels 0.8-1.3 cm long, 0.3-0.5 mm in diameter at the base, 0.5-1.0 mm in diameter at the apex, stout and becoming woody, erect or spreading, pale brown, falling with the mature fruit, not persistent; fruiting calyx not accrescent, the tube ca. 1 mm long, the lobes ca. 1 mm long, appressed to the berry. Seeds (5-)6-12 per berry, 1.6-2.1 mm long, 1.3-1.8 mm wide, flattened and tear-drop shaped with a subapical hilum, brownish, the surfaces minutely pitted, thin, the testal cells rectangular to pentagonal in outline. Stone cells 9-22 per berry, ca. 0.5 mm in diameter. Chromosome number: 2n =4x=48 ( Manoko et al. 2012).

Distribution

(Figure 56 ). Endemic to the southern highlands of Tanzania.

Ecology.

Grows on volcanic soils, frequent on the ash layer in charcoal-burning areas, also commonly cultivated; between 1,700 and 2,200 m elevation.

Common names.

Tanzania: insungwe [Malila people] ( Schippers 2000).

Uses.

Leaves used as spinach; berries eaten raw.

Preliminary conservation status

( IUCN 2016). Solanum umalilaense is known mostly from cultivation in the southern part of Tanzania; based on its range (EOO = 2,559 km2; EN) and the number of populations (AOO = 32 km2), it would be assigned a preliminary conservation status of EN (Endangered), but might be better considered DD (Data Deficient). It is protected by local people and its range is poorly known.

Discussion.

Solanum umalilaense can be distinguished from other African species of morelloids by its simple to branched and often leafy inflorescences, flowers with very short rounded calyx lobes and persistent, small, light yellowish-brown fruits. Solanum umalilaense produces a large number of inflorescences such that, at full anthesis, the plant appears to be covered with white flowers, strikingly different from other species in the section ( Manoko et al. 2012), except some populations of S. tarderemotum (the branched-inflorescence form previously recognised as S. florulentum ). Like S. tarderemotum , the berries fall with the pedicels still attached.

Manoko (2007) used AFLP molecular markers to assess the relationships of the tetraploid African species and found that S. umalilaense (as "Sp. A") was a member of a cluster including S. retroflexum (as S. hirsutum (Vahl) Dunal and S. retroflexum ) that itself clustered with S. tarderemotum .

More field work is needed in southern Tanzania and adjacent Zambia to determine the true range and morphological variation of S. umalilaense ; collections analysed to date come from what might be a single population.

Specimens examined. Tanzania. Iringa: Mufindi, Igowole, 10 Mar 1989, Kayombo & Kayombo 215 (MO); Mbeya: Maganjo village, Lwindi ward, 8 Jul 2010, Manoko 2010-1 (DSM, NIJ, WAG); Isangati village, Iyunga ward, 8 Jul 2010, Manoko 2010-2 (DSM, NIJ, WAG); Igala village, Holondo ward, 8 Jul 2010, Manoko 2010-8 (DSM, NIJ, WAG); Isangati village, Iyunga Mapinduzi ward, 9 Jul 2010, Manoko 2010-11 (DSM, NIJ, WAG); Isangati village, Iyunga Mapinduzi ward, 9 Jul 2010, Manoko 2010-12 (DSM, NIJ, WAG); nr Umalila Forest reserve, 9 Jul 2010, Manoko 2010-14 (DSM, NIJ, WAG); Uyole, Mbeya, 22 May 1968, Mwambunga 6 (DSM).

Figures

Figure 55. Solanum umalilaense A Habit B Flower and buds showing calyx shape C Inflorescence and leaves D Infructescence showing detail of winged stem. (A-D NIJ-A 24750133). Photos by G. van der Weerden.

Figure 56. Distribution of Solanum umalilaense.