Solanum lanceifolium
Citation:
Coll. 2: 286. 1789.
Type:
"West Indies", P. Isert s.n. (lectotype, designated by D’Arcy 1970: W! [W0022641]; isolectotypes: BM!, W! [W0022640, F neg. 33085: F!, MO!)
Written by:
Stephen Stern
Habit:
Vine, 1-4 m. Stems moderately armed with recurved, tan roselike prickles, these 1-2 mm long, the base 1-2 x 0.5-1 mm, densely pubescent with white to tan , porrect-stellate hairs, the stalks nearly absent to 1 mm, multiseriate, the rays 5-8, 0.5-1 mm, unicellular to multicellular, the midpoints nearly absent to 0.5 mm.
Sympodial structure:
Sympodial units difoliate, the leaves geminate, those of a pair slightly unequal.
Leaves:
Leaves simple, the blades 3-7 x 1-3 cm, ovate, chartaceous, slightly discolorous, dark green adaxially, light green abaxially, both leaf surfaces moderately to densely pubescent with hairs like those of the stem but with the midpoints 0.5-1 mm; major veins 3-6 on either side of the midvein, the secondary veins obscure, the midrib abaxially with a few to many recurved pirckles like those of the stem; base acute, often asymmetrical; margin unlobed; apex acute; petioles 0.5-2 cm, with recurved prickles like those of the stem.
Inflorescences:
Inflorescences 2-3 cm, extra-axillary, unbranched, with 5-15 flowers, apparently all perfect, the axes moderately to densely pubescent with hairs like those of the stem, unarmed; peduncle 0.5-1.5 cm; rachis 1.5-2.5 cm; pedicels 5-10 mm in flower, 10-30 mm in fruit, filiform, expanded distally, spaced 1-3 mm apart.
Flowers:
Flowers apparently all perfect, 5-merous. Calyx 2-4 mm long, the tube 1-2 mm, the lobes 1.5 x 0.5-1 mm, the lobes often reflexed, narrowly triangular, moderately to densely pubescent with hairs like those of the stem, unarmed fruiting calyx 3-5 mm, not accrescent in fruit. Corolla 1-2 cm in diameter, chartaceous, white, stellate, lobed nearly to the base, the lobes 5-10 x1-3 mm, lanceolate, moderately pubescent abaxially with hairs like those of the stem, nearly glabrous adaxially. Stamens 6-7 mm; filaments 1-2 mm long, glabrous; anthers 5-6 x 1-2 mm, attenuate, tapering connivent in bud, connivent to spreading in flower, yellow, the base cordate, the apex obtuse, the pores apical, directed slightly introrsely. Ovary glabrous; style 6-9 x 0.5-0.75 mm, exserted beyond stamens, cylindrical, white, glabrous; stigma 0.5-1 mm wide, green.
Fruits:
Fruit a thin to leathery skinned berry, 8-14 mm in diameter, globose, green when immature, orange to dark red when mature, glabrous.
Seeds:
Seeds 15-25 per fruit, 2-2.5 x 1.5-2 mm, reniform, brown, flattened, the surface netlike with many pits created by small raised ridges.
Chromosome number:
Not known
Distribution:
Solanum lanceifolium is common in disturbed areas and forest gaps from central Mexico through Central America and the Caribbean into northwestern South America at 100 -1600 (2900) m.
Phylogeny:
Solanum lanceifolium is a member of the Micracantha clade (section Micracantha) of the spiny solanums (Leptostemonum; Stern et al. 2011).
References:
D’Arcy, W.G. 1970. Jacquin names, some notes on their typification. Taxon. 19: 554-560.
Stern, S., M.F. Agra, & L. Bohs. 2011. Molecular delimitation of clades within new world species of the “spiny solanums” (Solanum subgenus Leptostemonum). Taxon.
The concept of S. lanceifolium presented above is a broad definition and encompasses much morphological variability. If one were to look at two specimens of S. lanceifolium there is a great likelihood that they would question whether they belong to the same species due to the great range of phenotypes in the species. However, drawing boundaries between phenotypes is nearly impossible due to the continuous variability of characters. Some of the most obvious differences in many collections are leaf size and pubescence. Leaves of many of the Mexico and Central America specimens are small with abaxial surfaces that are so densely pubescent that the mesophyll is not visible. Specimens from the Caribbean islands often have much larger leaves that are very sparsely pubescent which likely led to these being named as S. lanceifolium var. litorale. Because these phenotypic differences are continuous, it is not possible to draw boundaries and differentiate these as distinct species.
One example of local variation includes collections from Dominica, such as Whitefoord 7021 (BM) and Nicolson 2163 (MO), that have large leaves (to 15 x 5 cm) that are thinner and less pubescent than normal. However, other specimens from the Caribbean have large, densely pubescent leaves and some Central American specimens (notably some of the higher elevation collections from Nicaragua) have very large, sparsely pubescent leaves. The presence of these intermediates on the spectrum makes it necessary for me to “lump” these seemingly disparate phenotypes under a broad species concept.
The best characters to define S. lanceifolium are the presence of many small (1-2 mm long), broad-based, recurved prickles on the stem, the filiform pedicels that expand distally, especially in fruit, the small flowers with corollas 1-2 cm in diameter, and the generally small (3-7 x 1-3 cm), unlobed, membranaceous leaves that are moderately to densely pubescent below.
The lectotype of S. lanceifolium was a collection made by Isert in his 1787 trip to the West Indies that Jacquin saw for his 1789 description. The specimen at W was annotated by Jacquin and designated as the lectotype by D’Arcy (1970). This specimen is particularly nice because it is intermediate in many of the characteristics, such as leaf size and pubescence, that would at first glance appear to separate the Caribbean and Central American specimens. The type has slightly wider and more sparsely pubescent leaves than some Central American specimens but they are not as wide and are more pubescent than many Caribbean specimens.
The name S. crotonoides Sieber ex Presl is illegitimate as it was previously used by Lamarck in 1794; we have lectotypified it with the specimen at W because it has the best material from amongst the duplicates of this collection. The name S. obscurum is a herbarium name that was used but never validly published. Solanum preslei was also not validly published because it names S. crotonoides and S. inaequale as synonyms. The name S. inaequale was previously used by Hornemann in 1819 for a member of Solanum section Torva and then was used by Vellozo in 1829 for a species in Solanum section Geminata making it an illegitimate name.