Solanum myoxotrichum
Not known
Eastern and northern Madagascar with some collections from the east of Antananarivo and eastern Mahajanga; growing in wet montane forest; 1000–3000 m elevation.
Solanum myoxotrichum was one of the first three spiny Solanum species from Madagascar to be included in molecular phylogenetic studies (Bohs, 2005) and is a member of the Old World clade of subgenus Leptostemonum (Levin et al., 2006). It is a member of a somewhat well-supported Madagascar clade with other Malagasy species in the analyses of Vorontsova et al. (2013) and is most closely related to Solanum erythracanthum (with which it is sometimes synonymized).
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.
D’Arcy, W.G., & A. Rakotozafy 1994. Solanaceae. Famille 176, pp. 1-146. In Flore de Madagascar et des Comores, P. Morat (ed.). Muséum National D’Histoire Naturelle, Paris.
Levin, R.A., N.R. Myers, & L. Bohs 2006. Phylogenetic relationships among the "spiny" solanums (Solanum subgenus Leptostemonum). Amer. J. Bot. 93: 157-169.
Vorontsova, M. S., S. Stern, L. Bohs, and S. Knapp. 2013. African spiny Solanum (subgenus Leptostemonum, Solanaceae): a thorny phylogenetic tangle. Bot. J. Linn. Soc. 173: 176-193. doi:10.1111/boj.12053
Local Names. Madagascar: Angivo-isity (D’Arcy and Rakotozafy 1994).
Solanum myoxotrichum is a striking forest species with stems densely covered in reddish long-stalked trichomes. The main stems have denser indumentum than young shoots, consisting of trichomes with lignified stalks that reach over 2 mm in length, mixed with mature prickles up to 7 mm long and sessile porrect trichomes. All stages of prickle development can be observed. The elongate multiseriate stalks of stellate trichomes thicken to become orange and more robust, and eventually form small acicular prickles with stellate trichomes on the apices; as the prickles continue growing the apical trichomes are deciduous and the tip becomes sharp.
Solanum myoxotrichum occurs principally in the humid zones of Fianarantsoa, Toamasina and Antsiranana, with a few collections made in the subhumid zone of Antananarivo. The lower-elevation variants of S. myoxotrichum from drier habitats have shorter indumentum and show a gradual transition to the weedy and ubiquitous S. erythracanthum. Solanum myoxotrichum is maintained at species rank for convenience and because the number of intermediate collections is comparatively small; the somewhat intermediate S. forsythii is included within S. myoxotrichum on the basis of its wet forest habitat and relatively dense stem pubescence. Solanum myoxotrichum can be distinguished from S. erythracanthum by its calyx lobes of 3-7 mm long in flower (versus 1.5-2.5 mm in S. erythracanthum), copious indumentum on the main stems longer than 2 mm (versus glabrescent main stems in S. erythracanthum) and main stems usually wider than 4 mm in diameter (versus always under 4 mm in diameter in S. erythracanthum).
We have chosen the Kew duplicate of Baron 2805 (K00414178) as the lectotype of S. myoxotrichum because Baron 2805 is more widely distributed than the other collection (Central Madagascar, Jan 1882, Baron 1005 [K000414180]) cited in the protologue, and the duplicate at K was seen by Baker. We have chosen Forsyth-Major 387 (K000414181) as the lectotype of Solanum forsythii as it is composed of the best quality material of the duplicates found. Forsyth-Major 387 appears to be a mixed collection number: BM000887178, G00015055, and G00015056 have the date 25 January 1895 (contradicting the protologue) and acute leaf apices, while K000414181 has the date 4 January 1895 (matching the protologue) and acuminate leaf apices. The specimens labelled 25 January are probably not isosyntypes. The second collection cited in the protologue is from Joshimanitra forest, 10 Nov 1884, Forsyth-Major 115 (K000414182, BM000887176, G00015054) and is composed of inferior quality material.