Monanthotaxis Baill., Bull. Soc. Linn, Paris 2: 878, 1890

Couvreur, Thomas L. P., Dagallier, Leo-Paul M. J., Crozier, Francoise, Ghogue, Jean-Paul, Hoekstra, Paul H., Kamdem, Narcisse G., Johnson, David M., Murray, Nancy A. & Sonke, Bonaventure, 2022, Flora of Cameroon - Annonaceae Vol 45, PhytoKeys 207, pp. 1-532 : 165-167

Monanthotaxis Baill., Bull. Soc. Linn, Paris 2: 878, 1890

= Clathrospermum Planch. ex Benth., Gen. Pl. 1(1): 29, 1862.

= Enneastemon Exell J. Bot. 70 (Suppl. 1): 209, 1932.

= Exellia Boutique, Bull. Jard. Bot. État Bruxelles 21: 117, 1951.

= Atopostema Boutique, Bull. Jard. Bot. État Bruxelles 21: 121, 1951.

= Gilbertiella Boutique, Bull. Jard. Bot. État Bruxelles 21: 124, 1951.

Description.

Scrambling shrubs or lianas, up to 30 m tall, d.b.h. up to 11 cm; stilt roots or buttresses absent. Indumentum of simple hairs. Leaves: petiole 1-11 mm long, 1-3 mm in diameter; blade 3-35 cm long, 1.4-12.5 cm wide, linear to elliptic to ovate to obovate to oblong, apex acuminate to acute, base decurrent to subcordate, discolorous, whitish below; midrib sunken or flat; secondary veins 6 to 23 pairs; tertiary venation percurrent. Individuals unisexual or bisexual; inflorescences cauliflorous or ramiflorous on old or young foliate branches, axillary, leaf opposed or extra axillary. Flowers with (6-)9 perianth parts in 2 or 3 whorls, 1 to more than 50 per inflorescence with a peduncle from 1 to 70 mm long; pedicel 1-60 mm long; in fruit 2-55 mm long; bracts 2 to 3, one or two basal and one inserted on the pedicel at varying levels; sepals 3, valvate, free, 0.5-10 mm long, ovate to elliptic to triangular, apex acute or obtuse, base truncate; petals free; outer petals 3 or 6 (when petals in one whorl), valvate, 1-50 mm long, 1-25 mm wide, ovate to elliptic, apex acute to rounded, base truncate; inner petals (0-)3, valvate, 0.5-25 mm long, 0.3-10 mm wide, ovate to elliptic to rhombic, apex acute to rounded, base truncate; stamens 1 to more than 125, in 1 to 6 rows, 1-2 mm long, linear or cuneiform to clavate; anthers sometimes connate apically covering connectives, connective discoid to truncate to absent, glabrous or pubescent; staminodes 6 to 12(13) or absent; carpels free, 3 to 150, 1-4 mm long, stigma bilobed or cylindrical or elongate and flattened at top, pubescent or glabrous. Monocarps sessile or stipitate, stipes 1-25 mm long; monocarps 2 to 25, 6-60 mm long, 5-25 mm in diameter, moniliform, cylindrical to ellipsoid, apex rounded to apiculate, smooth or verrucose or weakly torulose; seeds 6-25 mm long, 4-11 mm in diameter, ellipsoid; aril absent.

Type species.

Monanthotaxis congoensis Baill.

A genus of scrambling shrubs or lianas with 79 known continental African species, from West, Central and East Africa, plus around 23 endemic species from Madagascar. In Cameroon 26 species are known, six endemic.

The genus Monanthotaxis is easily identified when sterile by its lianescent or scrambling habit, discolorous leaves with very glaucous lower surface, and percurrent (parallel) tertiary venation. Some species are unisexual and have cauliflorous inflorescences; some are confirmed as monoecious, but for others, even though male and female flowers are known, it remains to be confirmed if they occur on the same or different individuals. The stamen number is highly variable within the genus ranging from 1 or 2 to over 100 ( Hoekstra et al. 2018); some species have very characteristic large anthers fused towards the apex, hiding the small or absent connective ( M. bicornis , M. pellegrinii and M. zenkeri ). Some species also have staminodes varying in number from 6 to 12.

In the checklist to the plants of Mt Cameroon ( Cable and Cheek 1998, p. 11) the species M. oligandra Exell is cited as present, but its occurrence in the country is not confirmed by the recent taxonomic revision ( Hoekstra et al. 2021). Though we have not seen the specimen, M. oligandra is not known to occur north of South-West Democratic Republic of the Congo, so its presence in Cameroon is unlikely.

Taxonomy.

African species (excluding Madagascar) are revised in Hoekstra et al. (2021).