Solanum jamaicense
Citation:
Gard. Dict. ed. 8, no. 17. 1768.
Type:
JAMAICA. sin. loc., W. Houston s.n. (holotype: BM! [BM000815972]).
Written by:
Stephen Stern
Habit:
Shrub 1-2 m, occasionally scandent. Stems moderately armed with recurved, yellow to green roselike prickles, these 3-8 mm in length, the base 2-4 x 0.5-2 mm, moderately to densely pubescent with white, porrect-stellate hairs, the stalks nearly absent to 1 mm, multiseriate, the rays 6-8, 0.5-1mm, unicellular to multicellular, the midpoints absent to 1 mm.
Sympodial structure:
Sympodial units difoliate, the leaves geminate, those of a pair unequal.
Leaves:
Leaves simple, the blades 6-13x3-8 cm, rhombic, unlobed to 2-5 lobes per side, the sinuses cut less than 1/6 of the way to the midvein, the lobes obtuse, leaves chartaceous, slightly discolorous, dark green adaxially, light green abaxially, with both leaf surfaces sparsely to moderately pubescent with stellate hairs like those of the stem; major veins 3-6 on either side of the midvein, the midrib abaxially unarmed or with occasional prickles like those of the stem; base acute, decurrent onto petiole; apex acute to obtuse; petioles absent to 1 cm, moderately pubescent with hairs like those of the stem, unarmed or occasionally armed with prickles like those of the stem.
Inflorescences:
Inflorescences 1-3 cm, extra-axillary, unbranched, with 5-15 flowers, apparently all perfect, the axes moderately to densely pubescent with hairs like those of the stem but with the stalks to 1.5 mm, unarmed; peduncle absent to 0.5 cm; rachis 1-3 cm; pedicels 5-10 mm in flower, 10-15 mm in fruit, filiform, nearly contiguous, spaced 0.5-1.5 mm apart.
Flowers:
Flowers apparently all perfect, 5-merous. Calyx 2-7 mm long, the tube 1-2 mm, the lobes 3-5 x 0.5-1.5 mm, very narrowly triangular, moderately to densely pubescent with hairs like those of the stem but with the stalks to 1.5 mm, unarmed; fruiting calyx 4-9 mm, the lobes not accrescent in fruit. Corolla 1-2 cm in diameter, chartaceous, white to yellow-white, stellate, lobed nearly to the base, the lobes 4-6 x 1.5-3 mm, narrowly triangular, sparsely pubescent abaxially with hairs like those of the stem with midpoints either absent or to 1 mm, midpoints either white or occasionally purple, glabrous adaxially. Stamens 4-6 mm; filaments up to 1 mm, glabrous; anthers 3.5-5 x 1-2 mm, attenuate, tapering, connivent, yellow, the base cordate, the apex obtuse, the pores apical, directed introsely. Ovary very sparsely pubescent with multicellular, uniseriate glandular hairs 0.2-0.4 mm long; style 4-6 x 0.5-1.5 mm, exserted beyond stamens, cylindrical, white, sparsely pubescent with stellate hairs like those of the stem; stigma up to 1 mm wide, cylindrical, green.
Fruits:
Fruit a thin-skinned berry, 4-12 mm in diameter, globose, mottled green when immature, mottled orange or red when mature, glabrous.
Seeds:
Seeds 40-70 per fruit, 1-1.5 x 0.5-1 mm, reniform, brown, flattened, the surface netlike with many pits created by small raised ridges.
Chromosome number:
Not known
Distribution:
Solanum jamaicense is a weedy species of open fields, roadsides, or other disturbed areas from southern Florida through the Caribbean and Central America into northern South America and Brazil to northern Bolivia, at sea level to 900 m in elevation.
Phylogeny:
Solanum jamaicense is a member of the Micracantha clade (section Micracantha) of the spiny solanums (Leptostemonum; Stern et al. 2011).
References:
D’Arcy, W.G. 1973. Solanaceae. In R.E. Woodson eds., Flora of Panama. Annals of the Missouri Botanical Garden. 60: 573-780.
Stern, S., M.F. Agra, & L. Bohs. 2011. Molecular delimitation of clades within new world species of the “spiny solanums” (Solanum subgenus Leptostemonum). Taxon.
Solanum jamaicense is the most widespread of the species in sect. Micracantha and is a very common weed in pastures and roadsides in lowlands throughout the range of the section. While it can become scandent on other vegetation in weedy tangles, it is also the most shrublike species within sect. Micracantha.
There are a number of characteristics of S. jamaicense that are unusual in the section. Although it is often scandent on other vegetation, S. jamaicense often has a more erect growth form that is uncommon in the section, which are normally vining. The rhombic leaves that nearly lack a petiole due to the decurrent leaf base are unique in the section. The flowers of S. jamaicense are among the smallest of the section and, although the anthers remain tightly connivent, the style is often bent at the apex. Additionally, S. jamaicense has small (4-12 mm in diameter), thin-skinned fruits that are mottled during development and calyx lobes with long-stalked stellate hairs.
Phylogenetic results of Stern & Bohs (in prep) place S. jamaicense sister to S. lanceifolium, although with only moderate support (71% BS, 1.0 PP) and places them sister to the remainder of section Micracantha. This sister relationship was somewhat unexpected as S. lanceifolium shares many morphological characteristics with S. volubile, which has been considered a synonym of the former (D’Arcy 1973). The small flowers and berries of S. jamaicense and S. lanceifolium are perhaps the most obvious shared characteristic between these species.
Solanum jamaicense has some of the most difficult nomenclatural issues in the section, likely due to its widespread distribution but also because many names, such as S. acanthifolium and S. umbellatum, were not published but instead were listed by Dunal as herbarium names. The name S. brevipilosum is an illegitimate name because in the publication S. brevipilum is listed as a synonym. This was likely an attempt to correct the original spelling of S. brevipile. D’Arcy (1973) cited the P. Salzmann 384 specimen at G-DC as the lectotype for this species; however, this collection cannot be the lectotype because is not original material named in the 1813 description and the name is illegitimate since it had S. brevipilum listed in synonomy. A lectotype for this specimen should be chose from the Riedle collections at MPU, which were the basis for the original 1813 description. The name S. heterotrichum had two specimens cited by Dunal. The speciemen at G-DC is chosen as the lectotype because it has the best material.