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Magnoliopsida
Solanum trizygum Bitter
EOL Text
Montane And premontane forest from Mexico to the Cordillera de la Costa in Venezuela, absent from the Andes, from ca. 600-3200 m.
Solanum trizygum is superficially similar to S. conicum of the eastern Amazon, and is phylogenetically closely related to that species (Knapp & Helgason, 1997, Fig. 8). It differs from S. conicum in its more lanceolate leaflets that ate very shortly petiolate or sessile, and in its more elongate fruit. The fruit of S. trizygum also resembles that of S. savanillense, but is longer and has a more pronounced beak. Solanum trizygum is quite common locally in the cloud forests of Central America.The distribution pattern of Solanum trizygum, occurring in Central America and in the Cordillera de la Costa in Venezuela, is quite common in angiosperms (see Knapp, 1991a, b, 2002). This may be indicative of some dispersal in the past, but alternatively may support geological hypotheses linking the Cordillera de la Costa with the Pacific plate (see discussion in Knapp, 1991b).An un-numbered Moritz collection from Venezuela (BM, F, GH, W [F neg. 33118, F, MO, US, WIS]) distributed from W could also be type material of Solanum trizygum, but as it is labelled ‘Colombia, leg. Moritz’ it was excluded from consideration as a lectotype by Knapp & Helgason (1997).
Solanum trizygum is a member of the Solanum mite species group of section Pteroidea in the Potato clade (Bohs, 2005). Based on morphology (Knapp & Helgason, 1997), S. trizygum is sister to a group composed of S. conicum + (S. savanillense + S. uleanum).
- Bohs, L.. 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.
- Knapp, S.. A cladistic analysis of the Solanum sessile species group (section Geminata pro parte: Solanaceae). J. Linn. Soc., Bot. 106: 73-89.
- Knapp, S.. A revision of the Solanum sessile species group (section Geminata pro parte: Solanaceae). J. Linn. Soc., Bot. 105: 179-210.
- Knapp, S.. Solanum section Geminata (G. Don) Walpers (Solanaceae). Flora Neotropica 84: 1-405.
- Knapp, S. & T. Helgason. A revision of Solanum section Pteroidea Dunal: Solanaceae. Bull. Nat. Hist. Mus. London, Bot. 27: 31-73.
Habit
Somewhat woody shrub to 1 m. Stems ca. 5 mm in diameter, usually bright green and fleshy, completely glabrous, but occasionally with sparse reddish papillae (when dry) or simple uniseriate trichome scattered near the nodes.
Sympodial Structure
Sympodial units unifoliate.
Leaves
Leaves 10-40 x 5-10 cm, pinnate, elliptic, with 3-6 (most commonly 4) pairs of leaflets, glabrous or minutely papillose adaxially, occasionally with a few uniseriate trichomes along the veins abaxially, occasionally purple abaxially and along the rachis; petiole 2-5 cm long; lateral leaflets lanceolate to elliptic 4-15(-25) x 2-4 cm, with 6-8 pairs of primary veins, the base attenuate, only very occasionally oblique, the apex acuminate; petiolule 0.1 cm long; basal leaflets either equal to the laterals or somewhat smaller; terminal leaflet similar in shape to the laterals, 6-20 x 3-6 cm, the base attenuate, the apex acuminate; petiolule ca. 1 cm or less.
Inflorescences
Inflorescence axillary, 1-4(-9) cm long, simple, ca. 2-4 arising from a single axil, bearing 2-3 flowers at a time, with 20-30 pedicel scars, glabrous or minutely papillate at the tips. Buds elliptic, the calyx strongly 5-ridged (in dry specimens) in earl bud, ca. 3 x 2 mm, strongly exserted from the calyx tube. Pedicels at anthesis 1-1.5 cm, ca. 0.5 mm in diameter at the tip, nodding.
Flowers
Flowers with the calyx tube 1-1.5 mm, open-conical, the lobes deltate to broadly triangular, 0.5-1 x 0.5-1 mm, glabrous; corolla 9-10 mm, greenish white or white, lobed nearly to the base, the lobes reflexed at anthesis, minutely papillose at the margins and tips; anthers 2-2.5 x 1-1.5 mm, poricidal at the tips, free portion of the filaments 0.5-1 mm long, the filament tube absent; ovary conical, glabrous; style 5-6 mm long, minutely papillose in the lower half; stigma minutely capitate, occasionally somewhat clavate.
Fruits
Fruit a conical, green berry, the beak not abruptly narrowed, ca. 1-1.2 cm in diameter, 1.2-2.5 cm long, the surface rugose, the raised portions white, when ripe smelling distinctly of wintergreen; fruiting pedicels 1.5-2 mm long, ca. 3 mm in diameter at the apex, erect.
Seeds
Seeds 3.0 x 2.0-2.5 mm, ovoid-reniform to elliptic, greenish brown, ca. 40 seeds per fruit; epidermal cells sinuous and irregular, with anticlinal thickenings but without projections.