Monanthotaxis whytei (Stapf) Verdc. — Plate, 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 : 210

77. Monanthotaxis whytei (Stapf) Verdc. — Plate 6d–f; Map 47

Monanthotaxis whytei (Stapf) Verdc. (1971b) 29. — Popowia whytei Stapf (1905) 81. — Type: A. Whyte s.n. (holo K000198908 ), Liberia, Sino, Sinoe Basin , 1904.

[ Popowia prehensilis A.Chev.(1920) 11, nomen nudum. — Based on: A.J.B. Chevalier 16048 ( P00362640 ), Ivory Coast, Abidjan, Bingerville, 13 Dec. 1906; A.J.B. Chevalier 17077 ( P00362642 , P01982378 , P01982379 , P01982380 ), Ivory Coast, Abidjan, vallée de l’Agnieby, entre Guébo et Mbago, 2 Feb. 1907; A.J.B. Chevalier 17701 ( P01982383 ), Ivory Coast, Aboisso , entre Bianouan et Soubié, 27 Mar. 1907.]

Shrub or liana, to 20(–50) m long; young branches dark brown, covered with appressed to ascending, reddish brown hairs c. 0.2 mm long, becoming glabrous; old branches dark brown to blackish. Leaves: petiole 1–4(–7) mm long, 1.1–2.1 mm diam, grooved, indument slightly denser than that on young branches; lamina obovate to narrowly so, 8.8–19.4 by 3.5–8.5 cm, 1.7–2.8 times longer than wide, chartaceous to subcoriaceous, not punctate, discolorous, green above, glaucous below, above covered with erect, yellowish hairs, becoming glabrous, below sparsely covered with appressed, yellowish hairs c. 0.1 mm long, primary vein covered with few, yellowish hairs to 0.3 mm long, base narrowly subcordate, glands hardly visible, apex acute to slightly acuminate, acumen to 3 mm long, secondary veins 8–14 per side, curving upwards, tertiary venation percurrent, sometimes hardly visible. Inflorescences cauliflorous, ramiflorous or axillary, composed of solitary flowers or few-flowered fascicles to short glomerule-like rhipidia; sympodial rachis 2–8 mm long, densely covered with slightly erect, yellowish hairs 0.1–0.2 mm long; pedicels 7–11 mm long, 0.6–0.7 mm diam, fruiting pedicels 13–20 mm long, c. 1.6 mm diam, indument as on sympodial rachis; lower bracts triangular to ovate, 0.5–1.6 by 0.5–0.7 mm, indument as on sympodial rachis; upper bract in lower half or halfway the pedicel, triangular to lanceolate, 0.7–1.5 by 0.4–0.6 mm, indument as on sympodial rachis; flower buds globose. Flowers bisexual; sepals free, broadly ovate, 1–1.8 by 1.1–1.8 mm, densely covered with appressed, yellowish hairs, persistent in fruit; receptacle c. 2.3 mm diam, flat; petals dirty greenish yellow to yellow, 6, in two whorls, outer petals broadly ovate, 3.4–5 by 3.4–4.5 mm, outside covered with appressed, yellowish hairs, inside glabrous except for the margins, inner petals elliptic to ovate, 3–4 by 1.5–2.2 mm, outside with yellowish, short hairs on the primary vein, inside glabrous except for a few small hairs at the apex; stamens 9, in one whorl, free, obconical, 0.9–1.1 mm long, filaments c. 0.2 mm long, thecae latrorse, connective truncate, prolonged inward and outward, square seen from above, glabrous, staminodes 9, alternating with the stamens, 0.3–0.6 mm long, ovoid-triangular, glabrous; carpels 26–34, subcylindric, 1.1–1.3 by c. 0.2 mm, densely hairy, ovules 3, lateral, stigma elongate, 0.4–0.6 mm long, grooved, glabrous. Monocarps up to 10, yellow to orange when ripe, often with a white exudate, ellipsoid to subglobose, 15–38 by c. 8 mm, constricted between the seeds, verrucose, densely covered with appressed/ascending yellow hairs, becoming glabrous, but longer persistent at stipe and top, apex rounded to shortly apiculate, apiculum to 1 mm long, stipes 4.5–12 mm long, grooved. Seeds 1–3, globose to ellipsoid, 9–10 by 6–7 mm, ochre-brown to reddish brown, both ends rounded, raphe slightly visible as a longitudinal furrow from base to apex.

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

Habitat & Ecology — In primary forest, swampy forest, secondary forest, gallery forest and in savanna areas, on gravel, sandy soil, wet cliffs and on river banks. Altitude: 50– 600 m. Flowering: November to February,April to July; fruiting: all year round.

Preliminary IUCN conservation status — Least concern (LC). EOO: 934 306 km 2, AOO: 160 km 2. This species has a wide distribution and occurs in several nature reserves and has been collected several times quite recently. Therefore, this species is currently not under threat of extinction.

Notes — 1. Monanthotaxis whytei can be recognised by the cauliflorous or ramiflorous inflorescences, globose floral buds, and flowers each with 9 stamens and 9 small staminodes. The majority of specimens have angular stems and they can easily be recognised by this character in West Africa.

2. In an ontogenetic study, Ronse Decraene& Smets (1990) found that this species actually forms two whorls of staminodes, but the outer whorl already stops very early during the development and is not visible in mature flowers.

3. There are some differences among different collections in seed shape (subglobose to ellipsoid) and in stipe length, but no consistent correlating patterns were found.

Figures

Plate 6 a. Monanthotaxis trichantha (Diels) Verdc. a. Flowering branch. — b–c. Monanthotaxis trichocarpa (Engl. & Diels) Verdc. b. Flowering branch; c. fruiting branch. — d–f. Monanthotaxis whytei (Stapf) Verdc. d. Flower; e–f. inflorescences with flowers (a: LÖtter 1757; b: LÖtter 1624; c: LÖtter 1184; d–f: photographed in Botanical gardens Utrecht, no specimen collected). — Photos: a–c: M.C. Lötter; d–f: L.Y.T. Westra.

Map 47 Distribution of Monanthotaxis whytei (Stapf) Verdc.