Monanthotaxis gracilis (Hook.f.) P.H.Hoekstra, 1971

Hoekstra, P. H., Wieringa, J. J., Maas, P. J. M. & Chatrou, L. W., 2021, Revision of the African species of Monanthotaxis (Annonaceae), Blumea 66 (2), pp. 107-221 : 162

36. Monanthotaxis gracilis (Hook.f.) P.H.Hoekstra — Fig. 15a–g ; Map 22

Monanthotaxis gracilis (Hook.f.) P.H.Hoekstra in Guo et al. (2017) 14. — Uvaria gracilis Hook.f. in Hook.f. & Benth. (1849) 210. — Oxymitra gracilis (Hook.f.) Sprague & Hutch.(1916) 154. — Richella gracilis (Hook.f.) R.E.Fr. (1959) 139. — Friesodielsia gracilis (Hook.f.) Steenis (1964) 359. — Type: G. Don s.n. (holo BM000547066), Sierra Leone.

Oxymitra platypetala Benth. in Benth. & Hook. f.(1862) 472. — Cleistopholis platypetala (Benth.) Engl. & Diels (1901) 34. — Type: G. Mann 857 (holo K00198952 ), Sierra Leone, Southern Province, Bagroo river, Apr. 1861.

Unona millenii Engl. & Diels (1901) 40. — Type: H. Millen 149 (holo K not seen), Nigeria, Lagos, Mar. 1896.

Oxymitra rosea Sprague & Hutch. (1916) 154. — Richella rosea (Sprague & Hutch.) R.E.Fr. (1959) 139. — Friesodielsia rosea (Sprague & Hutch.) Steenis (1964) 361. — Type: P.A.Talbot 199 (holo BM000547067), Nigeria, Cross River State, Oban, 1911.

Scandent shrub or liana, 4–20 m long, 2–10 cm diam; young branches pale brown to brown, covered with appressed to ascending hairs c. 0.1 mm long, becoming glabrous; old branches pale grey. Leaves: petiole 2–4 mm long, 0.4–0.9 mm diam, grooved, indument as on branches; lamina oblanceolate, 4–16.5 by 1.4–5.7 cm, 2.4–3.3 times longer than wide, subcoriaceous, not punctate, glaucous below, above glabrous, but primary vein covered with few, yellowish, short hairs, below glabrous except for a few yellowish hairs 0.1–0.2 mm long on the primary vein, base narrowly subcordate, appearing cuneate, with thickened black margin, apex acute to acuminate, acumen to 20 mm long, secondary veins 7–9(–10) per side, curving upwards, tertiary venation slightly percurrent. Inflorescences extra-axillary or leaf-opposed, composed of lax (1- or) 2- or 3-flowered rhipidia; sympodial rachis 2–5 mm long, covered with appressed, yellowish, short hairs; pedicels 15–50 mm long, 0.3–0.4 mm diam, fruiting pedicels 0.3–0.8 mm diam, indument as on sympodial rachis; lower bracts lanceolate, 1–2 by 0.4–0.6 mm, densely to sparsely covered with appressed, yellowish, short hairs; upper bract in lower half of the pedicel, ovate to lanceolate, 1.5–2.5 by 0.8–1 mm, sparsely covered with appressed, yellow hairs; flower buds ovoid to deltoid. Flowers bisexual; sepals free, ovate, 3 (or 4), 6–6.2 by 3.8–4.5 mm, apex obtuse, sparsely covered with appressed hairs, persistent in fruit or not; receptacle c. 3 mm diam, convex; petals greenish, yellowish, olive or tinged with pink, 6, in two whorls, outer petals ovate to lanceolate, 12–30 by 7–12 mm, outside covered with appressed, yellowish hairs, becoming glabrous, apex of inside covered with glandular-like hairs, base glabrous; inner petals ovate to rhombic, 5–9 by 3–5 mm, outside covered with appressed, short hairs, inside glabrous or sparsely covered with hairs; stamens 80–125, in three to five whorls, free, linear-oblong, 0.7–1.2 mm long, filaments c. 0.1 mm long, thecae latrorse, connective truncate, circular seen from above, hiding thecae, glabrous, staminodes absent; carpels 17–24, subcylindric, 1.2–1.9 by 0.2–0.4 mm, densely hairy, ovules 2–5, lateral, stigma elongate, 0.4–0.6 mm long, hairy. Monocarps 10– 20, red when ripe, moniliform, each part globose to ellipsoid with 1–5 seeds, 13–35 by 4–5 mm, sparsely covered with appressed hairs, densely so when young, apex apiculate, apiculum 1–2 mm long, stipes 4–8 mm long, slightly grooved. Seeds 1–5, ellipsoid, c. 6 by 4 mm, tawny brown, ends rounded, raphe not visible or slightly visible from base to apex on both sides.

Distribution — Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Nigeria, Cameroon, Equatorial Guinea.

Habitat & Ecology — In primary forest, secondary forest, swamp forest and gallery forest, on river banks and summit ridges. Altitude: 10– 870 m. Flowering: January, March, April, August to November; fruiting: October to April, June, July.

Vernacular name — Sierra Leone: Mabwe (N.W. Thomas 1461).

Preliminary IUCN conservation status — Least concern (LC). EOO: 1 240 501 km 2, AOO: 148 km 2. This species is known from many locations and quite some reserves.

Notes — 1. Monanthotaxis gracilis and M. quasilanceolata can easily be distinguished from all other Monanthotaxis species by the long and slender pedicels with ovoid to deltoid flower buds and ovate to lanceolate outer petals. Monanthotaxis gracilis differs from M. quasilanceolata by having pale grey branches, very short hairs on the branches and pedicels, small lanceolate bracts, a globose instead of conical connective, more and shorter carpels, and much smaller monocarps and seeds.

2. The number of stamens differs between Upper Guinea with 110–125 stamens and Lower Guinea with 80–90 stamens. However, stamens of only 2 flowers from the west of Upper Guinea have been counted and more material in flower of especially Ghana and Ivory Coast is needed to verify if there is a gradient in the stamen number.

Figures

Map 22 Distribution of Monanthotaxis glabra P.H.Hoekstra (■, D means uncertain det) and M. gracilis (Hook.f.) P.H.Hoekstra (●).

Fig. 15 a–g. Monanthotaxis gracilis (Hook.f.) P.H.Hoekstra. a. Flowering branch; b. sepal; c. outer petal; d. inner petal; e. stamen, side and front view; f. carpel and longitudinal section of carpel; g. fruit. — h–o. Monanthotaxis obovata (Benth.) P.H.Hoekstra. h. Flowering branch; i. sepal; j. outer petal; k. inner petal, inner and side view; l. androecium and gynoecium; m. stamen, front and side view; n. carpel and longitudinal section of carpel; o. fruits. — p–u. Monanthotaxis stenosepala (Engl. & Diels) Verdc. p. Flowering branch; q. flower, side view; r. inner petal, inner and side view; s. stamen from behind and side view; t. gynoecium; u. longitudinal section of carpel. — Modified from Engler & Diels (1901) table 15, 17 and 18.