Solanum ochranthum
Citation:
Solan. Synopsis 6. 1816.
Type:
Ecuador. “in regno Quitense”, Humboldt & Bonpland s.n. (lectotype, P [Morton neg. 8721] designated here]; isolectotypes, P [Morton neg. 8272], P [LL neg. 519], P [LL neg. 514; Cibachrome K]).
Written by:
Peralta, I.E., S. Knapp & D.M. Spooner
Habit:
Large woody vines, to 8-10 m tall, clambering over vegetation. Stems 60-80 mm at base, younger stems green, pithy, 4-5 mm, pale greenish-brown, densely white pubescent with simple uniseriate trichomes, the longest 4-6-celled, 1.5-2.5 mm long, from multicellular bases, mixed with shorter white trichomes ca. 0.5 mm long, usually from unicellular bases and glandular trichomes ca. 0.05 mm long, with a 4-celled glandular head.
Sympodial structure:
Sympodial units 5-plurifoliate; internodes 2-10 cm long, or larger on older stems (not usually on herbarium specimens).
Leaves:
Leaves interrupted imparipinnate, 13-35 cm long, 11-20 cm wide, green, markedly paler abaxially, densely pubescent with simple uniseriate trichomes, adaxially sparsely to moderately pubescent with transparent patent trichomes 0.5-2 mm long, with multicellular bases, the trichomes breaking off and the surface very slightly rough to the touch, tiny 1-celled trichomes with a large 1-celled glandular head also present, abaxially the pubescence desne and soft, of weaker-walled and tangled 8-10-celled trichomes with unicellular bases, these densest along the veins, the glandular trichomes like those of the adaxial surface but sparser, the lamina surface pale abaxially with dark venation in dry specimens; primary leaflets 3-5 pairs, the basal pair much smaller than the rest, elliptic to oblanceolate, the base truncate to completely decurrent on the rachis, oblique basiscopically, the margins entire, the apex acute to acuminate; terminal leaflet usually larger than the laterals, 6-11 cm long, 2-4 cm wide, the petiolule 0.6-1.1 cm long; lateral leaflets 7.5-10 cm long, 2-3.5 cm wide, decurrent basiscopically to the rachis or with a tiny petiolule to 0.2 cm long; secondary leaflets absent; tertiary leaflets absent; interjected leaflets 7-16, opposite to subopposite, 0.1-0.5 cm long, 0.1-0.4 cm wide, in sets of 2 or 3 between the primary leaflets, completely decurrent onto the leaf rachis; petiole 2-4 cm long; pseudostipules usually present and well-developed in all nodes, 0.5-1.5 cm long, 0.4-1.5 cm wide, pubescent like the leaves.
Inflorescences:
Inflorescences 8-20 (30) cm long, many times (to 4-5 times) branched, with 2-60 (+) flowers, ebracteate, peduncle 3.5-12 cm long, densely pubescent like the stems, the pubescence more abundant at the apices of the branches. Pedicels 1-1.5 cm long, articulated at the middle, the articulation often swollen and conspicuous. Buds ca. 1 cm long, 0.5 cm wide, elliptic, straight, with the corolla more than halfway exserted from the calyx just before anthesis.
Flowers:
Flowers with the calyx tube 0.25-0.4 cm long, the lobes 0.2-0.5 cm long, 0.2-0.3 cm wide, deltate and irregularly splitting, the tips acute, densely white pubescent with 1-2-celled trichomes to 0.5 mm long, from unicellular bases; corolla 2.4-3.5 cm in diameter, rotate to rotate-stellate, bright golden yellow, the tube 0.8-1.1 cm long, the lobes 0.5-1 cm long, 0.5-1 cm wide, abaxially densely pubescent with simple uniseriate trichomes over entire surface, these more abundant and tangled at the tips and along the midveins, the lobes spreading at anthesis; staminal column absent, the stamens free, straight, the filaments 1.5-2 mm long, glabrous or densely white pubescent, the anthers 0.5-0.6 cm long, the sterile apical appendage absent; ovary conical, glabrous or with a few white uniseriate trichomes to 0.5 mm long, at the apex; style 1-1.3 cm long, pubescent ½-3/4 of its length, more densely pubescent basally, 0.5-0.7 mm in diameter, exserted 1-3 mm above the apex of the stamens; stigma capitate, occasionally somewhat 2-lobed, green.
Fruits:
Fruit 2-5 cm in diameter(or sometimes larger), the walls thick and woody, 2-3-locular, green, glabrous; fruiting pedicels 1.5-2.5 cm long, thickened and woody, to 0.5 cm in diameter, straight or slightly bent at the articulation; calyx lobes in fruit 0.2-0.3 cm long, 0.2-0.3 cm wide, thickened and woody, slightly reflexed and breaking off.
Seeds:
Seeds 4.3-5.0 mm long, 3.0-3.5 mm wide, 0.8-1.0 mm thick, obovate to orbicular, pale brown, pubescent with hair-like outgrowths of the lateral testa cell walls, which give a silky appearance to the surface, winged (0.7-0.8 mm wide) round the entire seed border.
Chromosome number:
2n = ploidy missing =24 voucher missing = (Correll 1962)
Distribution:
Central Colombia (Cordillera Central and Occidental) to southern Peru (Dept. Apurimac); montane forests, 1900-4100 m.
Phenology:
Solanum ochranthum flowers and fruits throughout the year, but has a marked flowering peak in June (Smith & Peralta 2002).
Phylogeny:
Solanum ochranthum is a member of the Potato clade (sensu Weese & Bohs, 2007); within the tomatoes and wild relatives it is a member of section Juglandifolia.
References:
Correll, D.S. 1962. The potato and its wild relatives.
Contr. Texas Res. Found., Bot. Stud. 4: 1-606.
Smith, S., & I.E. Peralta 2002. Ecogeographic surveys as tools for analyzing potential reproductive isolating mechanisms: an example using Solanum juglandifolium Dunal, S. ochranthum Dunal, S. lycopersicoides Dunal, and S. sitiens I.M. Johnston.
Taxon 51: 341-349.
Knapp, S. 2002. Tobacco to tomatoes: a phylogenetic perspective on fruit diversity in the Solanaceae.
J. Exp. Bot. 53: 2001–2022.
Solanum ochranthum is most closely related to S. juglandifolium, and can be easily distinguished from the latter by the markedly paler undersurfaces of the leaves, the more numerous interjected leaflets and the rotate, usually more golden yellow corollas and acute calyx lobes. The paler color of the undersurfaces is partly due to the dense pubescence but also due to a paler lamina. Some specimens of S. ochranthum have somewhat rough adaxial leaf surfaces, but they never as rough as S. juglandifolium. Close examination with a dissecting microscope should allow the two taxa to be easily distinguished. For a discussion of the equivocal nature of the key in Correll (1962), see S. juglandifolium. Solanum ochranthum occurs at slightly higher elevations than does S. juglandifolium, particularly where the two taxa are sympatric.
Solanum ochranthum has large fruits (to more than 5 cm in diameter, see Fig. 6H in Smith & Peralta 2002) with markedly woody walls at maturity, a character state unusual in Solanum in general, although S. abitaguense and S. cucullatum of section Geminata and S. lycocarpon (a spiny Solanum from the cerrados of southern South America) also have very large fruits (Knapp 2002a).
The many varieties of S. ochranthum described by Bitter reflect the variability in leaf size and number of leaflets in the species, and the variability in pubescence throughout the range. Some populations are more pubescent than others, but the difference is only one of degree and the character varies randomly throughout the distributional range of S. ochranthum.
Specimens of Solanum ochranthum collected by Jameson but distributed as Jameson 829 at BM, NY, US, W [LL neg. 788]) have been annotated as isotype material of S. ochranthum var. connascens by J.G. Hawkes, possibly due to their overall morphological similarity to the holotype in W. Solanum ochranthum is, however, remarkably uniform in the Ecuadorian Andes, so these sheets are possibly from another collection made by William Jameson, a British ornithologist collecting in the Quito area in the 19th century. Jameson’s localities are not consistent even within a single numbered collection, but the holotype in W has no locality, while sheets of Jameson 829 are labelled “Andes of Quito”. These may be isotypes, as they are very similar to the holotype of var. connascens, but in the absence of specific evidence to the contrary, these specimens labeled Jameson 829 cannot be considered to have come from the same gathering as the type.