Solanum monachophyllum
Citation:
Solan. Syn. 33. 1816.
Type:
VENEZUELA. Río Orinoco, A. Humboldt & A. Bonpland s.n. (holotype: P-Bonpl.!; isotype: B-W! [B04412-010]).
Written by:
Stephen Stern
Habit:
Shrub to scandent shrub 1-2 m. Stems sparsely armed with recurved, yellow to brown roselike prickles, these 1-2.5 mm long, the base 1-2 x 0.5-1 mm, moderately pubescent with tan to rusty, porrect-stellate hairs, the stalks nearly absent to 1 mm, multiseriate, the rays 6-10, 0.5-1 mm, unicellular to multicellular, the midpoints reduced and appearing gland-tipped to 1 mm.
Sympodial structure:
Sympodial units difoliate, the leaves usually geminate but occasionally spaced up to 2 cm apart, leaves of a pair slightly unequal.
Leaves:
Leaves simple, the blades 2-11 x 1-5 cm, ovate, leaves chartaceous, slightly discolorous, dark green adaxially, green to whitish green abaxially, with both leaf surfaces moderately to densely pubescent with white hairs like those of the stem with midpoints often elongated to 1 mm; major veins 4-6 on either side of the midvein, the midrib unarmed; base acute; margin unlobed to 2-3 obtuse lobes per side, the sinuses cut less than ¼ of the way to the midvein; apex acute to obtuse; petioles 1-2 cm, moderately to densely pubescent with hairs like those of the stem, unarmed or occasionally with sparse prickles like those of the stem.
Inflorescences:
Inflorescences 3-4 (7) cm, leaf-opposed to extra-axillary, unbranched, with 3-8 flowers, apparently all perfect, the axes glabrous to moderately pubescent with hairs like those of the stem, unarmed; peduncle 0.5-2 cm; rachis 1-3.5 (6) cm; pedicels 5-20 mm in flower and fruit, nearly contiguous, spaced 1-3 mm apart.
Flowers:
Flower apparently all perfect, 5-merous. Calyx 2-5 mm long, the tube 3-4 mm, the lobes 1-2 x 0.25-0.75 mm, triangular, moderately pubescent with hairs like those of the stem, unarmed; fruiting calyx 7-10 mm, lobes triangular, not accrescent in fruit. Corolla 1.5-2 cm in diameter, chartaceous, white, stellate, lobed nearly to the base, the lobes 7-12 x 1-2.5 mm, narrowly triangular, moderately pubescent abaxially with hairs like those of the stem, glabrous adaxially. Stamens 6-8 mm; filaments 2-3 mm long, glabrous; anthers 4-6 x 0.5-1.5 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 to sparsely pubescent with glandular hairs; style 10-12 x 0.25-0.75 mm, occasionally reduced to 3-4 mm in length implying andromonoecy, exserted beyond stamens, cylindrical, white, glabrous; stigma to 1 mm wide, clavate.
Fruits:
Fruit a berry, 8-12 mm in diameter, globose, green when immature, orange when mature, glabrous.
Seeds:
Seeds 25-40 per fruit, reniform, brown, 1.5-2 x 1-1.5 mm, flattedned, the surface netlike with many pits separated by small raised ridges.
Chromosome number:
Not known
Distribution:
Solanum monachophyllum is found along riverbanks, often occurring on sandbars that may be up to 3 m below the high water mark of the Guiana Shield in Suriname, French Guiana, Guyana, and Venezuela and into the Amazon Basin on the Rio Negro and Amazon Rivers in Brazil at 20-250 (450) m.
Phylogeny:
Solanum xxxxxxx is a member of the Micracantha clade (section Micracantha) of the spiny solanums (Leptostemonum; Stern et al. 2011).
References:
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 monachophyllum is found at low elevations throughout northern South America from Bolivar Department, Colombia in the west to French Guiana in the east and Para, Brazil in the south. Nearly all collection labels indicate that the species occurs along or near rivers or streams. Field observations of S. monachophyllum on the Essequibo River in Guyana found the species growing on sandbars with what appeared to be a persistent woody base and annual growth of small, herbaceous shoots. These sandbars were above water in the dry season but the high water marks on the riverbanks indicated that they could be as much as 3 m underwater in the wet season.
Although there is variability between collections, S. monachophyllum is consistently the least prickly species of the section, perhaps due to the fact that it rarely climbs on other vegetation and thus does not require the roselike spines for climbing. The leaves of S. monachophyllum are widest below the midpoint and are typically unlobed but rapidly growing shoot might have 2-3 coarse lobes per side. The stamens of S. monachophyllum often appear to be disorganized, that is some stamens in a given flower might be slightly longer or spreading while others are more tightly connivent.
Phylogenetic results weakly support (67% BS, 1.0 PP) a sister relationship between S. monachophyllum and S. leucopogon (Stern and Bohs in prep). This relationship is unexpected as the species differ in habitat, geographic location, and multiple morphological characters. The low resolution of the backbone of the phylogeny and the unique morphological characteristics of S. monachophyllum make it difficult to definitively place within the section.
Solanum cucyense and S. topirito were both published without Latin diagnoses, making them not validly published.
The epithet is from the Greek “monachos-” meaning “single or solitary” and “-phyll” meaning “leaf”.