Solanum barbisetum Nees, Trans. Linn. Soc. London 17(1): 51 1834.

Aubriot, Xavier & Knapp, Sandra, 2022, A revision of the " spiny solanums " of Tropical Asia (Solanum, the Leptostemonum Clade, Solanaceae), PhytoKeys 198, pp. 1-270 : 1

4. Solanum barbisetum Nees, Trans. Linn. Soc. London 17(1): 51 1834.

Figs 2H , 8

Solanum eriophorum Dunal, Prodr. [A. P. de Candolle] 13(1): 249. 1852. Type. Myanmar. Tanintharyi: “Tavoy” [Dawei], 12 Aug 1827, N. Wallich s.n. [Wallich Catal. Burm. 1328] (holotype: G-DC [G00145974]).

Type.

Myanmar. Tanintharyi Region: “Tavoy” [Dawei], Aug 1827, N. Gómez 9071 (lectotype, designated by Hul and Dy Phon 2014, pg. 34: K [K000759381]; isolectotypes: GZU [GZU000255503], LE) .

Description.

Herbs to small shrubs to 1 m tall, heavily armed. Stems erect, terete, densely prickly and pubescent, the pubescence deciduous with age leaving only prickles and bristles on older stems; prickles of varying sizes to 0.5 cm long, broad-based, straight, yellowish tan in dry material, purplish black or yellowish tan in live plants, grading into long-stalked bristles and stellate trichomes; pubescence of porrect-stellate trichomes, mixture of sessile, short- and long-stalked, often recorded as purple-tinged or blackish red, the stalks multiseriate, to 3 mm long, the rays 4-6, 0.5-1 mm long, thin and brittle, the midpoints absent on stalked trichomes, the sessile trichomes with elongate midpoints to 2 mm long, always longer than the rays; new growth densely pubescent with mixture of short- and long-stalked stellate trichomes; bark of older stems greyish brown. Sympodial units difoliate, the leaves not geminate, or occasionally unifoliate in very small plants. Leaves simple, shallowly lobed, the blades (7-)12-30 cm long, (5-)10-17 cm wide, 1.5-1.7 times longer than wide, broadly elliptic to somewhat ovate, chartaceous, discolorous (paler green beneath fide Maxwell 91-651), sparsely armed along the midrib and major veins with prickles to 1 cm long; adaxial surface dark green, sparsely pubescent with sessile porrect-stellate trichomes, the rays 0-4, 0.1-0.5 mm long, the midpoints 2-3 mm long, delicate and thin; abaxial surface with similar sessile porrect-stellate trichomes, but these denser, especially along the veins; major veins 4-7 pairs, densely pubescent especially abaxially, in live plants often purple-tinged; base abruptly truncate, somewhat oblique; margins shallowly lobed, the lobes 4-7 on each side, occasionally somewhat secondarily lobed, to 1 cm long, more or less broadly deltate, apically acute, the sinuses less than halfway to the midrib; apex acute; petioles 3-9 cm long, half as long to almost as long as the leaf blades, prickly and sparsely pubescent, the prickles to 1 cm long, straight, grading into bristles that themselves grade into to a few long-stalked stellate trichomes, the pubescence largely of sessile stellate trichomes with 5-6 rays 0.5-1 mm long and midpoints to 2 mm, always longer than the rays. Inflorescences (1-)3-10 cm long, internodal and lateral, unbranched, with 10-40 flowers, few flowers open at any one time, densely bristly and pubescent with trichomes like those of the stems, the bristles sparser distally with early deciduous rays at the apex grading into prickles; peduncle 0.5-2 cm long, unarmed or armed with a few prickles; pedicels 0.5-0.8 cm long, 0.5-0.7 mm in diameter at the base and apex, slender and nodding at anthesis, densely bristly and stellate-pubescent like the inflorescence axes, articulated at the base; pedicel scars irregularly spaced 3-4 mm apart. Buds long-tapering and somewhat fusiform, almost completely enclosed in the foliaceous calyx. Flowers 5-merous, heterostylous and the plants weakly andromonoecious, with most flowers long-styled and only the most distal short-styled, these drop after flowering and the whip-like inflorescence axis tip persists in fruit. Calyx with the tube 2.5-5.5 mm long, deeply cupulate to somewhat urceolate, densely bristly with bristles to 5 mm long, these elongating in fruit, the lobes 5-8 mm long, 3-4 mm wide, lanceolate to broadly triangular, densely stellate-pubescent abaxially with sessile porrect-stellate trichomes with 4-6 weak rays and an elongate midpoint. Corolla 1.8-2.2 cm in diameter, white or violet (usually adaxially white and abaxially violet, but not always), deeply stellate, lobed nearly to the base, interpetalar tissue absent, the lobes 8-10 mm long, 1.5-3 mm wide, narrowly deltate, spreading to recurved at anthesis, glabrous adaxially, densely stellate-pubescent abaxially with sessile trichomes with elongate midpoints, these densest at the tips. Stamens slightly unequal, with 2 slightly longer than the rest; anthers 8.5-10 mm long, 2 slightly longer, ca. 1 mm wide, strongly tapering, yellow, glabrous, poricidal at the tips, the pores directed distally, not elongating to slits with drying; filament tube minute, glabrous; free portion of the filaments minute, glabrous, the anthers almost sessile. Ovary conical, glabrous; style (long-styled flowers) 8-10 mm long, glabrous, ca. 3 mm long in short-styled flowers; stigma capitate, the surfaces minutely papillose, bright green in live plants. Fruit a globose berry, 6-12 per infructescence, 1-1.4 cm in diameter, pale greenish white, completely enclosed in the bristly calyx tube, the pericarp thin and more or less shiny, glabrous; fruiting pedicels 0.7-0.9 cm long, ca. 1 mm in diameter at the base, 1.7-2 mm in diameter at the apex, somewhat woody, spreading to pendent; fruiting calyx greatly expanded to enclose the berry, the tube densely bristly and surrounding the berry, the lobes to 1 cm long, 0.3 cm wide, stellate-pubescent. Seeds 20-30 per berry, 2.5-5 mm long, (1.5)2-3 mm wide, flattened reniform, pale tan or yellowish brown (white in live plants), the surfaces minutely pitted, the testal cells pentagonal in shape. Chromosome number: not known.

Distribution

(Fig. 9 ). Solanum barbisetum occurs from southern China (Yunnan) and northeastern India to Laos and Thailand.

Ecology and habitat.

Solanum barbisetum grows in open areas, in fields and along forest edges in mixed broadleaf forests; usually from 300 to 2,000 m elevation, more rarely at sea level.

Common names and uses.

China. ci bao qie ( Zhang et al. 1994). Thailand. Nakhon Si Thammarat: ma uk pa (Rabil Bunnag 204); North: ma khûa chê pâ [Lao] (Winit Wanadorn 1424).

Fruits (ripe berries) said to be eaten in India ( Jain and Borthakur 1986).

Preliminary conservation status

( IUCN 2019). Least Concern (LC); EOO (1,244,077 km2), AOO (248 km2). Solanum barbisetum is widely distributed and is a plant of disturbed areas such as field and forest edges; the small AOO certainly reflects collection bias.

Discussion.

Solanum barbisetum is a distinctive species with its elongate inflorescences, berries enclosed in an accrescent calyx and copious long-stalked stellate trichomes on all vegetative parts. It is morphologically most similar to S. praetermissum and to a lesser extent S. involucratum ; it shares with both those species berries enclosed in accrescent calyces and large leaves. Solanum involucratum is not sympatric with S. barbisetum and is a more robust plant with pubescent berries and shorter inflorescences. Solanum praetermissum is more or less sympatric with S. barbisetum and has been treated as a variety of S. barbisetum in the past ( Clarke 1883, see description of S. praetermissum ). Solanum barbisetum differs from S. praetermissum in its bristlier pubescence, with the calyx trichomes becoming stiff and prickly as the fruit matures and its more attenuate leaf bases. The calyx pubescence of S. barbisetum is often purple-tinged; this is even visible in quite old herbarium sheets.

Solanum barbisetum was treated under this species name for Bhutan in Mill (2001), but with the note that "Most specimens from our area labelled ' S. barbisetum ' belong, or appear to belong to S. griffithii " ( Mill 2001: 1059). The correct name for S. griffithii (Prain) Wu & Huang is S. praetermissum (see description); care should be taken with the identification of material from Bhutan for these taxa.

The phylogenetic affinities of S. barbisetum are unclear. In the analyses of Aubriot et al. (2016a) it is resolved as sister to the ' S. expedunculatum and relatives’ clade ( S. expedunculatum Symon, S. heteracanthum Merr. & L.M.Perry, S. involucratum and S. procumbens ) but this is only supported with Bayesian inference. It might also be closely related to the morphologically similar S. praetermissum but that relationship is not clearly supported in molecular analyses ( Vorontsova et al. 2013; Aubriot et al. 2016a).

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 2. Vegetative characters for tropical Asian spiny solanums A large and densely hairy repand leaf of S. lasiocarpum (Meeboonya et al. RM 287, Thailand) B small, pubescent, very shallowly lobed leaf of S. miyakojimense (field photograph, unvouchered, Taiwan) C entire, pubescent leaf of S. robinsonii (Nuraliev 3031, Vietnam) D glabrescent and deeply dissected leaf of S. virginianum (Sampath Kumar et al. 126968, India) E conical straight prickles on a pubescent young stem of S. hovei (field photograph, unvouchered, India) F strongly hooked prickles on a glabrous young stem and on the abaxial leaf surface of S. trilobatum (Meeboonya et al. RM 242, Thailand) G needle-like purple prickles on the adaxial leaf surface of S. cyanocarphium (field photograph, unvouchered, Vietnam) H pubescent young stem of S. barbisetum armed with prickles and bristles (Suksathan et al. PS 3832, Thailand). Photograph credits: A, B, D-F X. Aubriot C, G M. Nuraliev H D. Pedersen.

Figure 8. Solanum barbisetum Nees A herbarium specimen collected in Laos in 1932 (Poilane 20487, P 00055977) B habit and leaves (Suksathan et al. PS 3832, Thailand) C detail of the calyx with stellate trichomes and bristles (Suksathan et al. PS 3832, Thailand) D many flowered inflorescence (Suksathan et al. PS 3832, Thailand) E detail view of a flower (Suksathan et al. PS 3832, Thailand). Photograph credits: A CC-BY, Museum national d'Histoire naturelle, Paris B-E D. Pedersen.

Figure 9. Distribution of S. barbisetum.