Solanum variabile
Citation:
Flora 21, Beibl. 2: 80. 1838.
Type:
Brazil. Rio de Janeiro, C. Martius s.n. (syntype, M [F neg. 6548]); Brazil. São Paulo: Taubatá [probably Taubaté], C. Martius s.n. (syntype, M [Morton neg. 8754); possible syntype, M [Morton neg. 8755]).
Last edited by:
Nee, M.
Written by:
Nee, M.
Habit:
Shrubs 1–3 (–5) m high, the internodes (0.5) 2–4.5 cm long. Stems densely tomentose with yellowish ferruginous porrect stellae, gradually glabrescent, the stalks 0.2–1 mm long, the rays 6–8, 0.2–0.4 mm long, the midpoint very short, a mere point; stems unarmed or sparsely armed with straight, thick-based prickles to 4 mm long, or the prickles to 8 mm long on vigorous shoots and sparsely tomentose in the lower 2/3.
Sympodial structure:
Sympodial units plurifoliate, not geminate.
Leaves:
Leaves simple, the blades 4–15 (–20) × 2–8 (–12) cm, 2–3 times as long as wide, often narrowly lanceolate, but on vigorous sprouts ovate to widely ovate in general outline, thick-chartaceous, greenish tawny and with the surface partially visible adaxially, more densely tomentose abaxially, the stellae of both leaf surfaces short-stalked and similar to those of the stem, the stalks 0.4–0.7 mm long and relatively thick, the blade unarmed even on vigorous young growth, or very rarely with a few straight prickles to 2 mm long on midrib abaxially; principal lateral veins 4–7 on each side of the midvein; base acute to rounded, rarely auriculate on very vigorous growth; margin usually entire, less often shallowly sinuous or even lobed, with very deep lobing on the most vigorous growth and the lobes on these again lobed; apex acuminate to attenuate; petioles 0.8–2.7 cm long, stellate-tomentose, unarmed, or rarely with a few prickles like those of the stem.
Inflorescences:
Inflorescences 5–11 (–15) cm in flower, about the same length in fruit, terminal, eventually overtopped and lateral, 2–6-branched, with 15–45 flowers, with all flowers apparently perfect, the axes stellate-tomentose like the stem, unarmed; peduncle 2–4.5 cm long and erect in flower, the branches 1.5–7.5 cm long; pedicels 10–13 mm in flower, to 22 mm long in fruit and gradually thickened above, spaced ca. 5 mm apart, articulated at the base.
Flowers:
Flowers homostylous, 5-merous. Buds ovoid, densely and closely stellate-tomentose. Calyx 4.5–5 mm long, the tube 3–4 mm long, the lobes ovoid-triangular, ca. 2.5 × 2 mm, splitting somewhat irregularly in the sinuses and thus longer in fruit but scarcely accrescent, unarmed, finely stellate-tomentose abaxially, glabrous adaxially. Corolla 2–4 cm in diameter, rotate-pentagonal with well-developed interpetalar tissue, white, the midzone oblong-lanceolate, ca. 15 × 4–5 mm, densely and finely stellate-tomentose abaxially, the lobes 5–6 × ca. 12 mm, glabrous adaxially except for very fine tomentum at the tip. Stamens with filaments 1.5–2.3 mm long; anthers free, 6.5–8.5 × 1.7–2.1 mm, attenuate, yellow, often drying dark, with minute apical pores directed distally and slightly adaxially, the pores not enlarging, but the anthers splitting longitudinally upon drying from a fissure further down. Ovary with a few simple, gland-tipped hairs; style 10–11 mm long, filiform, glabrous except for a few simple gland-tipped hairs near the base; stigma capitate.
Fruits:
Fruit a berry, 1.1–1.4 cm in diameter, globose, the immature fruits green, turning orange when ripe, glabrous.
Seeds:
Seeds 3.6–4 × 2.7–3.1 mm, flattened-reniform, yellowish, the surface minutely pitted, nearly smooth.
Chromosome number:
Not known
Distribution:
Southeastern Brazil from Edo. Rio de Janeiro to Rio Grande do Sul and one collection with imprecise locality data from Paraguay, growing at edges of various types of humid forests and in clearings, secondary growth, roadsides and shrubby places, from near sea level to 1500 m.
Phylogeny:
Solanum variabile belongs to subgen. Leptostemonum sect. Torva (Nee, 1999), but its relationships within that group have not been assessed with molecular data.
References:
Nee, M. 1999. Synopsis of Solanum in the New World.
Pp. 285–333 in M. Nee, D. E. Symon, R. N. Lester & J. P. Jessop (eds.), Solanaceae IV: Advances in Biology and Utilization. Royal Botanic Gardens, Kew.
Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum).
Amer. J. Bot. 93: 157-169.
Perhaps to Martius this was a “variable” species, but aside from the multiplicity of leaf shapes which is often found in sect. Torva, Solanum variabile is easily recognized and distinctive in the area where it occurs. The only other species of sect. Torva which share its range are S. guaraniticum to the south and southwest which is a smaller plant with more numerous and acicular spines on the stems, and S. scuticum mainly to the north which has inflorescences shorter and lateral at all stages and smaller flowers. Solanum paniculatum is common in part of the range of S. variabile; S. paniculatum has strongly bicolorous leaves due to the soon glabrate upper leaf surface. Superficially S. variabile is more similar to several species of non-spiny Solanum in the region such as S. rufescens of sect. Brevantherum s.l. (Nee, 1999) or even S. mauritianum of sect. Asterochlaena (sect. Brevantherum s.s.), Nee, 1999, but it can be immediately distinguished from either of those species by the presence of prickles and the attenuate anthers with small terminal pores.
The name Solanum repandum Vell. will probably have to be lectotypified on tab. 123 since the Vellozo herbarium is apparently no longer extant.