Solanum montanum [L. ]

Solanum montanum

Citation author:

Citation:

Sp. Pl. 1: 186. 1753.

Type:

Peru. Probably Moquegua, Ilo, illustration in Feuillée, Journal des Observations Physiques, Máthematiques et Botaniques, 3: 65, pl. 45 (46 in text). 1725. (lectotype: designated by Knapp and Jarvis 1990).

Last edited by:

Bennett, J.

Written by:

Bennett, J.

Habit:

Perennial herb, often scandent or prostrate, 10–30 (–50) cm tall, arising from a subterranean spheroidal swollen caudex 10–30 (–40) mm in diameter, occasionally elongate and up to 75 mm long. Stems slender, glabrous to sparsely pubescent or rarely moderately pubescent, the hairs simple, uniseriate, unicellular or multicellular, up to 0.5 mm long.

Sympodial structure:

Sympodial units unifoliate, not geminate.

Leaves:

Leaves simple, the blades (1.1–) 1.7–8.5 (–13.5) x (0.8–) 1.0–6.0 (–11.0) cm, 0.8–2.2 times as long as wide, ovate to elliptic, succulent or semi-succulent, glabrous to sparsely pubescent, rarely moderately to densely pubescent adaxially and abaxially, particularly along the veins, the hairs simple, uniseriate, multicellular, up to 0.5 mm long; base decurrent; margin subentire to deeply lobed with 2–3 pairs of lobes, the lobes 0.3–2.0 (–4.0) x 0.4–1.0 (–2.2) cm, the lobe apex acute; leaf apex acute; petioles 0–1.5 (–4.5) cm, sometimes indistinct and with a wing up to 5 mm wide each side, pubescent with hairs like those of the leaf lamina.

Inflorescences:

Inflorescences 2.0–11.5 (–19.0) cm, sometimes arising midway along the petiole or midrib of the associated leaf, unbranched or branching once, with 4–8 (–10) flowers, all flowers perfect, the axes moderately pubescent, the pedicels more densely so, the hairs appressed, simple, uniseriate, multicellular, sometimes purple, up to 2 mm long; peduncle (1.5–) 3–8 (–11.5) cm; pedicels 0.5–1.4 (–2.0) cm at anthesis, 11–25 mm in fruit, spaced 5–10 (–15) mm apart in fruit, articulated at the base.

Flowers:

Flowers with the calyx 5.5–9.5 mm long, the tube 1.0–3.5 mm, the lobes equal, 4.5–6.0 x 1.0–2.0 mm at anthesis, 3.5–5.0 x 2.0–2.2 mm in fruit, ovate to elliptic, the apex acute to obtuse, moderately to densely pubescent abaxially with simple, uniseriate, unicellular or multicellular hairs, these sometimes purple, up to 1 mm long, glabrous to sparsely pubescent adaxially. Corolla 1.5–2.6 cm in diameter, pentagonal, chartaceous, white, lilac, purple or violet, often with purplish markings along the abaxial surface, the tube 1.0–1.5 mm long, the lobes 7.5–13 x 6–13 mm, glabrous to densely pubescent abaxially, especially along the midveins, with simple, uniseriate, multicellular hairs, these sometimes purple, up to 0.5 mm long, glabrous adaxially. Stamens 5, equal; filament tube 1.0–1.5 mm long, glabrous; filaments equal, 1.2–2.5 mm long, glabrous; anthers equal, 2.7–3.5 (–5.2) x 0.9 x 1.2 (–1.4) mm, oblong, yellow, not connivent, poricidal at the tips, the pores tear-drop shaped, rapidly opening into longitudinal slits with age. Ovary glabrous; style ca. 5.5 x 0.2 mm, cylindrical, straight, glabrous; stigma clavate, 0.8–1.5 x 0.5–0.7 mm.

Fruits:

Fruit 0.6–1.1 cm in diameter, globose, glabrous, pale green to whitish, sometimes with white markings, stone cells absent or a few present, angular, ca. 1.0 x 0.7 mm.

Seeds:

Seeds 1.2–1.4 x 0.8–1.0 mm, flattened, glabrous, pale to dark brown or black, the surface deeply pitted.

Chromosome number:

Not known

Distribution:

Chile [Regions I (Tarapacá), II (Antofagasta), III (Atacama), IV (Coquimbo), and V (Valparaíso)] and Peru (Departments of Ancash, Arequipa, Lima, Ica, La Libertad, Lambayaque, Moquegua, and Tacna). On sandy or rocky lomas, 5–3400 m in elevation.

Phenology:

Flowers all year round, but predominantly August to September.

Phylogeny:

This species belongs to the Regmandra clade of Bohs (2005), an isolated clade within the non-spiny solanums.

Commentary:

Solanum montanum is a common plant of the lomas of coastal Peru. Some specimens are notable for the swelling of the subterranean caudex which forms a small ‘tuber-like’structure. Although this is not homologous to the true tubers of potato (S. tuberosum), this feature has given rise to its common name ‘papa de loma’. Field investigations of populations of S. montanum have shown that this character is not constant and may perhaps be related to environmental conditions (e.g. rainfall). In general, plants that develop a swollen caudex have a small, compact habit, and with leaves that are to some degree petiolate with a subentire margin (similar to the type illustration of S. montanum). In contrast, other specimens (similar to the type specimen of S. phyllanthum) have a more robust and spreading habit, with leaves that are strongly decurrent on a winged petiole and with a lobed margin. In this respect they are similar to S. paposanum from high altitude regions of Chile, with which they share the unusual arrangement of the inflorescence in which the peduncle arises some way along the midrib of a bract-like leaf. However, the leaves of S. paposanum are always densely velutinous whereas those of S. montanum are subglabrous. A whole range of intermediate forms can be found and S. phyllanthum Cav. is here reduced to synonymy with S. montanum.

References:

Hooker, W.J. 1827. Witheringia montana. Mountain Witheringia, or St. Lorenzo Potatoe.
Curtis's Bot. Mag. 54(n.s.1): 2768.

Knapp, S. & C.E. Jarvis 1990. The typification of the names of New World Solanum species described by Linnaeus.
J. Linn. Soc., Bot. 104: 325-367.

Bohs, L. 2005. Major clades in Solanum based on ndhF sequences.
Pp. 27-49 in R. C. Keating, V. C. Hollowell, & T. B. Croat (eds.), A festschrift for William G. D’Arcy: the legacy of a taxonomist. Monographs in Systematic Botany from the Missouri Botanical Garden, Vol. 104. Missouri Botanical Garden Press, St. Louis.

Solanaceae Source

A global taxonomic resource for the nightshade family

Solanaceae

Solanum montanum L.

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