You selected: Solanum trisectum in DC., Prodr. 13(1): 36. 1852. Status: Accepted.
Solanum trisectum , in DC., Prodr. 13(1): 36. 1852. Type: Portugal. Madeira: sin. loc., 1839, Lemann s.n. (holotype, G-DC, IDC microfiche 800:2060.3.4).
Synonyms
Nycterium triphyllum , Trans. Cambridge Philos. Soc. 6: 536. 1838 Type: Portugal. Madeira: Lemann or Lippold, two syntypes probably at CGE, see discussion.
Normania triphylla , Fl. Madeira 2(1) : 87. 1872. Type: Based on Nycterium triphyllum Lowe.
Last edited by Knapp, S. July 2006. Description written for PBI: Solanum by Knapp, S.
Habit
Herb to fleshy subshrub to 1 m; stems ca. 5 mm in diameter, hollow, erect, green, densely glandular pubescent, the trichomes ca. 0.5 mm long, the glands unicellular.
Sympodial structure
Sympodial units 3-4-pluri-foliate, the inflorescences becoming more crowded near the growing tip of the plant.
Leaves
Leaves 3-lobed to 3-foliate, sometimes with only a single basal lobe or unlobed on upper stems, 4-8 x 2-9 cm, the lower lobes ca. 8 x 5 cm, elliptic, the terminal lobe ca. 8 x 5 cm, ovate, widest in the middle, with 5-6 pairs of primary veins, densely glandular pubescent on both surfaces, the upper surface with sparse simple uniseriate trichomes to 1 mm long on the lamina, the lower surface more densely pubescent with simple uniseriate trichomes on the veins and lamina; base truncate or cordate (if leaves unlobed); margins entire or shallowly toothed, densely glandular ciliate, the trichomes ca. 0.5 mm; apex acute to acuminate; petiole 1.5 –5 cm, densely glandular pubescent.
Inflorescences
Inflorescences internodal, just below leaf, 2.5-8 cm long, simple, with 6-9 flowers, densely glandular pubescent with simple gland-tipped trichomes ca. 0.5 mm long; pedicel scars widely spaced 0.5-1 cm apart, flush with the rachis; peduncle 0.5-2 cm. Buds ellipsoid, strongly exerted from the calyx just before anthesis. Pedicels at anthesis 1-1.3 cm, ca. 1 mm in diameter, slender and erect, densely glandular pubescent, the trichomes 1-2 mm long.
Flowers
Flowers with the calyx tube broadly cup-shaped, 2-3 mm long, the lobes 5-6 mm long, narrowly elliptic, sparsely pubescent with simple uniseriate trichomes to 2 mm long abaxially, glandular adaxially, the apex acute; corolla 3-3.5 cm in diameter, pale purple, the lobes ca. 1 mm, minutely triangular, flattened or slightly reflexed at anthesis, densely papillose on the margins and tips of lobes; anthers heteromorphic, the 2 longest 7-9 x 1-1.5 mm, 2 mid-length anthers 5-6 x 1-1.5 mm, shortest anther ca. 3 x 1-1.5 mm, poricidal at the tips, the pores lengthening to slits with age, yellow in color, all but the shortest curved and bearing horns ca. 1 mm at 2-4 mm from the base; free portion of the filaments 2-3 mm, minutely glandular, the filament tube less than 1 mm; ovary conical, glabrous; style 0.7-0.8 cm, strongly curved upwards; stigma minutely capitate, papillose.
Fruits
Fruit a flattened globose berry, 1-1.5 cm in diameter, reddish orange or red when mature, the pericarp thin; fruiting pedicels 1-1.5 cm, not markedly woody, ca. 1 mm in diameter, slightly nodding; fruiting calyx enlarged, spreading at fruit maturity.
Seeds
Seeds ca. 5 x 4 mm, ovoid, dark reddish brown, with irregularly crenate margins, the surfaces shallowly pitted, the testal cells with straight walls.
Distribution
Extremely rare endemic of Madeira, known only from laurisylva (laurel forest) in the north of the island.
Phylogeny
Solanum trisectum is a member of the Normania clade of Bohs (2005), and was previously recognised as one of two species (the other being S. nava) of the endemic Macaronesian genus Normania.
Commentary
Solanum trisectum is an extremely rare plant, and was thought to be extinct until collected in 1991 in the laurel forests of northern part of Madeira (Short, 1994). Considered by Dunal (1852) as a member of his subsection Tuberarium (potatoes and relatives), S. trisectum and its close relative S. nava of the Canary Islands were considered as a distinct section of Solanum by Bitter (1912, 1917). Francisco-Ortega et al. (1993) recognised these two species as the genus Normania, differentiated from Solanum on the basis of the horned anthers, zygomorphic flowers, and distinct seed and pollen morphology. Molecular studies indicate that these species (and their close relative S. herculeum, previously recognised as the genus Triguera) form a distinct clade within a larger, monophyletic Solanum (Bohs & Olmstead, 2001).
Solanum trisectum can be distinguished from S. nava by its 3-foliate leaves, its more densely glandular parts and its yellow anthers with horns about one-third of the way from the base. The species is endemic to the island of Madeira, and has only been found in the northern part of the island in laurel forest. Its restricted range and lack of known populations makes it of considerable conservation concern on a global scale. Solanum trisectum can be given a preliminary conservation assessment of Endangered (EN), using the IUCN Red List criteria. The instability of populations of this species (Francisco-Ortega et al. 1993) will make conservation difficult. Solanum trisectum is cultivated (as Normania triphylla) at the Botanic Garden of the Radboud University of Nijmegen (http://www.bgard.science.ru.nl/). Plants of S. trisectum have naturalized in the area of the National Botanic Garden in Brest, France (R.N. Lester pers. comm. in Bohs & Olmstead, 2001), but I have seen no herbarium specimens from that area.
The typification of Solanum trisectum has been widely misinterpreted. In coining the name Solanum trisectum, Dunal (1852: 36) cited a specimen in G-DC collected by Charles Lemann in Madeira and “Nycterium triphyllum Lowe ex h. DC”. He did not explicitly cite Lowe’s published description of Nycterium triphyllum, only the annotation on the herbarium specimen in G-DC (IDC 800: 2060.3.4), thus the two names are heterotypic and the G-DC sheet collected by Lemann is the holotype of S. trisectum. Others have assumed that because Solanum triphyllum Vell. (Fl. Flum. 2: 120.1827) has priority, Dunal was proposing a replacement name, which in fact there is no evidence he was doing. A sheet at Kew is a possible isotype, and is dated July 1837. Child (1990) indicated that an isotype of S. trisectum was “Lehmann 1030” at BM, but no such specimen can be found, and he misdesignated the collector as Lehmann, who did not collect in Madeira. It is possible that he was referring to the sheet at K, but that specimen is without a number, and was collected by Lemann, a known collector in Madeira. Others (Francisco-Ortega et al., 1993; Bohs & Olmstead, 2001) have all assumed, incorrectly, that S. trisectum was based on Lowe’s Nycterium triphyllum, and have assumed both names were based on the same material.
The typification of Nycterium triphyllum is more complicated and still not satisfactorily resolved. Lowe (1838) cited two specimens in his original description of Nycterium triphyllum, as follows: “Hab. in Madera rariss: in parte Septentrionali prope S. Vicente secus vias intervenit Car. Lemann M.D.: in orientali prope Portella serius detexit Lippold. Ex insulis Canariensibus, in Herbario Lemanniano siccum quoque vidi.” Francisco-Ortega et al. (1993) incorrectly assumed Child’s (1990) designation of the “isotype” of S. trisectum was a lectotypification of Nycterium triphyllum as well. Lemann’s herbarium is mostly at the University of Cambridge (CGE), the lectotype of Nycterium triphyllum will need to be sought there.
References
- Bitter, G. 1912. Solana nova vel minus cognita II. Repert. Spec. Nov. Regni Veg. 11: 1-18.Bitter, G. 1912. Solana nova vel minus cognita II. Repert. Spec. Nov. Regni Veg. 11: 1-18.
- Bitter, G. 1917. Solana Africana II. Bot. Jahrb. Syst. 54: 416-506.Bitter, G. 1917. Solana Africana II. Bot. Jahrb. Syst. 54: 416-506.
- 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.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.
- Child, A. 1990. A synopsis of Solanum subgenus Potatoe (G. Don) (D’Arcy) (Tuberarium(Dun.) Bitter (s.l.)). Feddes Repert. 101: 209-235.Child, A. 1990. A synopsis of Solanum subgenus Potatoe (G. Don) (D’Arcy) (Tuberarium(Dun.) Bitter (s.l.)). Feddes Repert. 101: 209-235.
- Dunal, M.F. 1852. Solanaceae. Pp. 1-690 in A. P. DeCandolle (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 13(1). Victoris Masson, Paris, France.Dunal, M.F. 1852. Solanaceae. Pp. 1-690 in A. P. DeCandolle (ed.), Prodromus Systematis Naturalis Regni Vegetabilis 13(1). Victoris Masson, Paris, France.
- Francisco-Ortega, J., J.G. Hawkes, R.N. Lester & J.R. Acebes-Ginovés 1993. Normania, an endemic Macaronesian genus distinct from Solanum (Solanaceae). Plant. Syst. Evol. 185: 189-205.Francisco-Ortega, J., J.G. Hawkes, R.N. Lester & J.R. Acebes-Ginovés 1993. Normania, an endemic Macaronesian genus distinct from Solanum (Solanaceae). Plant. Syst. Evol. 185: 189-205.
- Short, M.J. 1994. XCV. Solanaceae. Pp. 295-303, in Press, J.R. & M.J. Short (editors) Flora of Madeira. HMSO, London.Short, M.J. 1994. XCV. Solanaceae. Pp. 295-303, in Press, J.R. & M.J. Short (editors) Flora of Madeira. HMSO, London.
