Solanum gonyrhachis [S.Knapp ]

Solanum gonyrhachis

Citation author:

S. Knapp

Citation:

Bull. Br. Mus. Nat. Hist. (Bot.) 19: 105. 1989.

Type:

Bolivia. La Paz: Prov. Nor Yungas, 2 km by road (ca. 1 km by air) NE and below Chuspipata, 2950 m, 16 17'30"S, 67 49'W, 29 Oct 1984, Nee & Solomon 30221 (holotype NY; isotypes BH, K).

Last edited by:

Knapp, S.

Written by:

Knapp, S.

Habit:

Spindly shrubs or hemiepiphytes, branches ca. 1 m long; young stems and leaves sparsely pubescent with lax uniseriate simple trichomes 0.5-1 mm long, these sparser but still present on older branches; the branches arching and slender; bark of older stems grey.

Sympodial structure:

Sympodial units unifoliate.

Leaves:

Leaves narrowly ovate, widest in the proximal third of the blade, shiny above, with uniseriate trichomes like those of the stems along the midrib, glabrous beneath, the blades 6-9 x 2-2.5 cm, with 4-6 pairs of main lateral veins, these not prominent above, except the keeled midrib, prominent and brown below (dry specimens), the apex long-acuminate, ciliate, the extreme tip rounded, the base truncate, somewhat cordate; petioles minute, 1-1.5 mm long, sparsely pubescent with uniseriate trichomes like those of the stems.

Inflorescences:

Inflorescences opposite the leaves or internodal, filiform and simple, 2-6.5 cm long, zig-zag at the pedicel scars, 5-15-flowered, with only 2 or 3 flowers on the inflorescence at a time, sparsely pubescent with simple, uniseriate trichomes 0.5-1 mm long; pedicel scars evenly spaced ca. 5 mm apart, the axis of the inflorescence bending ca. 80-90 at each scar. Buds globose when young, later ellipsoid or obovoid, sparsely pubescent with the uniseriate trichomes. Pedicels at anthesis filiform, purplish, deflexed, 0.9-1 cm long, tapering from the calyx tube to a slender base less than 0.5 mm in diam.

Flowers:

Flowers with the calyx tube conical, 1-1.5 mm long, strongly 5-ribbed, the ribs black in dry material, sparsely pubescent with uniseriate simple trichomes ca. 0.5 mm long, the lobes deltoid, apiculate, 0.5-1 mm long, sparsely pubescent with the trichomes like those of the tube, the tips of the apiculae densely papillose; corolla white, 0.8-1 cm in diam., lobed nearly to the base, the lobes planar or slightly reflexed at anthesis, the tips and margins of the lobes minutely papillose; anthers 2-2.5 x ca. 1 mm, poricidal at the tips, the pores tear-drop shaped; free portion of the filaments 0.5-0.6 mm long, the filament tube 0.1-0.2 mm long; ovary glabrous; style 3-5 mm long; stigma capitate, the surface minutely papillose.

Fruits:

Fruit not known.

Seeds:

Seeds not known.

Distribution:

Known only from middle to high elevations in NW Bolivia, in cloud forest, perhaps occasionally growing as a hemiepiphyte.

Phylogeny:

Solanum gonyrhachis is a member of the Solanum dolosum species group (Knapp, 2002) of the Geminata clade (Bohs, 2005).

Commentary:

Solanum gonyrhachis is a rare species, only collected from a single locality. This sparse occurrence (sensu Rabinowitz, 1981) is common in the S. confine and S. dolosum species groups.

Both S. gonyrhachis and its close relative S. dolosum have ciliate leaf apices, an unusual character in section Geminata. These species, with S. habrocaulon, are closely related to the members of the S. confine species group, but are segregated here because they are so distinctive morphologically. Label information of the type specimen indicates that the plant was growing as a hemiepiphyte, a habit also attributed to S. dolosum (see above).

The locality information on the specimen collected by Rusby at the falls of Madeira in western Brazil is surely a labelling error. The plant is definitely S. gonyrhachis, but the habitat of the lower Rio Madeira is very different from the cloud forests of the type locality (Nee, pers. comm.). Labelling errors often occurred with plants sent back from early botanical expeditions to South America, and Rusby did pass through habitat very like that of the type locality on his way down the eastern slopes of the Bolivian Andes.

References:

Rabinowitz, D. 1981. Seven forms of rarity.
Pp. 205-217 in H. Synge (ed.) Biological aspects of rare plant conservation. Wiley & Sons, New York.

Knapp, S. 2002. Solanum section Geminata (G. Don) Walpers (Solanaceae).
Flora Neotropica 84: 1-405.

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

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Solanaceae

Solanum gonyrhachis S.Knapp

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