Solanum cutervanum
Citation:
Ann. K.K. Naturhist. Hofmus. 7: 7. 1892.
Type:
Peru. Cajamarca: Cutervo, Jelski 30 (holotype, W [F neg. 33065]).
Last edited by:
Knapp, S.
Written by:
Knapp, S.
Habit:
Shrubs to small trees, 1-7 m tall; young stems and leaves densely covered with loosely branching golden tree-like trichomes; leaf scars somewhat raised, the stem not winged; bark of older stems dark reddish-brown, sparsely pubescent with the tree-like trichomes of the young stems. New growth densely pubescent with golden tree-like trichomes above and below.
Sympodial structure:
Sympodial units plurifoliate, branching monochasial or dichasial.
Leaves:
Leaves elliptic or occasionally narrowly elliptic (type), 6.5-13 cm x 1.7-5 cm, with 8-12 pairs of secondary veins, the adaxial surfaces of the blades drying dark, sparsely pubescent with golden tree-like trichomes, these mostly along the veins, the abaxial sides pubescent with golden trichomes like those of the adaxial surfaces, the pubescent denser than that above, the apex acute, the base acute, not winged on to the petiole; petiole 0.5-2 cm long, densely golden pubescent.
Inflorescences:
Inflorescences terminal, later appearing lateral or in the fork of the branches, densely pubescent with loose golden tree-like trichomes like those of the young stems, pyramidal, 4-10 cm long, branching ca. 10 times, with 10-20 flowers. Pedicels inserted in a sleeve ca. 0.5 mm long, densely pubescent with golden tree-like trichomes, slightly nodding at anthesis, 0.7-1.3 cm long, tapering from a basal diameter of 0.5 mm to an apical diameter of 1 mm. Buds elliptic, the corolla strongly exserted from the calyx tube.
Flowers:
Flowers with thecalyx tube conical, 1.5-2 mm long, lobes deltoid, 1.5-2 mm long, densely pubescent abaxially with golden tree-like trichomes, densely pubescent abaxially with dendritic and simple trichomes; corolla violet or occasionally white, 1.5-1.8 cm in diameter, lobed 3/4 of the way to the base, the lobes planar at anthesis, densely pubescent abaxially with tiny dendritic trichomes, these denser at the tips of the lobes; stamens with anther 3.4-4 mm long, 1-1.5 mm wide, poricidal at the tips, the pores becoming slit-like with age, free portion of the filaments 1-1.5 mm, occasionally slightly pubescent near the corolla, filament tube absent; ovary glabrous or with a few dendritic trichomes at the apex, glabrate in fruit; style 5-7 mm long, sparsely to densely pubescent at the base or along its entire length with golden dendritic trichomes; stigma bi-lobed, the surface minutely papillose.
Fruits:
Fruit a globose, purplish-black berry, with thin pericarp, 1-1.2 cm in diameter; fruiting pedicel woody, nodding to more or less erect, ca. 1 mm in diameter at the base.
Seeds:
Seeds reddish-brown, flattened lenticular, c. 810 per fruit, 3-4 mm x 2.5-3.5 mm, the surfaces minutely pitted.
Distribution:
Highland Peru from Piura to Puna, in rocky uplands, cloud forests and along trails in forest, from 2500-3300 m.
Phylogeny:
Solanum cutervanum is a member of the Solanum nitidum species group of the Dulcamaroid clade (Bohs, 2005).
References:
Knapp, S. 1989. A revision of the Solanum nitidum species group (section Holophylla pro parte: Solanaceae).
Bull. Br. Mus. Nat. Hist. (Bot.) 19: 63-112.
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.
Solanum cutervanum had long been confused with and placed in the synonymy of S. nitidum. Specimens of both these species were previously annotated as S. pulverulentum Pers., perhaps due to their superficial similarity and sympatric distribution. The two species, however, are very different. Solanum cutervanum has golden or brownish tree-like trichomes on stems, leaves and inflorescences and black berries, while S. nitidum has more delicate, greyish, strictly dendritic trichomes and red ripe berries.
Solanum cutervanum is closely related to S. ruizii, also from central Peru. It differs from that species in its often dichasial branching, rounded leaf bases, smaller flowers and deltate calyx lobes. These sister taxa are sympatric and flower size may contribute to reproductive isolation. Some populations of S. cutervanum from N Peru have broadly elliptical leaves superficially reminiscent of S. aureum Dunal, a vining species with golden pubescence. Solanum aureum, however, does not possess the sleeve-like pedicel insertion characteristic of the Solanum nitidum group.
Unfortunately the species name Solanum pulverulentum Pers., so long in use for this species, is a later homonym of S. pulverulentum L., itself a superfluous name of S. tomentosum L., and African spiny species. Linneaus only used the epithet pulverulentum in the 1759 edition of his Systemae Naturae, and in later publications reverted to the use of his original epithet tomentosum.