Monanthotaxis chasei (N.Robson) Verdc.

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 : 140

14. Monanthotaxis chasei (N.Robson) Verdc. — Map 10

Monanthotaxis chasei (N.Robson) Verdc. (1971b) 25. — Popowia chasei N. Robson (1958) 155. — Type: N.C. Chase 5375 (holo K000198970 ; iso BM000553829 , LISC000389 ,S, SRGH not seen), Zimbabwe, Manicaland, Mutare, Umtali , S.T. Commonage , 610 m, 26 Dec. 1951.

Scandent shrub or liana, to 10 m long; young branches reddish brown, densely covered with appressed, yellow-brown hairs 0.2–0.4 mm long, becoming glabrous, old branches dark brown. Leaves: petiole 4–7 mm long, 1–1.5 mm diam, terete, indument as on branches; lamina elliptic to obovate, 5.7–14.6 by 2.7–7.6 cm, 1.5–2.5 times longer than wide, chartaceous, sometimes slightly punctate, dark green above, glaucous below, above covered with appressed, white hairs 0.2–0.3 mm long, becoming glabrous, primary vein covered with slightly longer-persistent, yellow hairs, below sparsely to rather densely covered with appressed, yellowish hairs 0.2–0.3 mm long, more densely so on the primary vein, base rounded to subcordate, with slightly thickened black margin, apex acute to acuminate, acumen to 15 mm long, secondary veins 9–13 per side, slightly curving or straight and curving at end near margin, tertiary venation percurrent, hardly visible above. Inflorescences extra-axillary or leaf-opposed, composed of solitary flowers to 3-flowered fascicle-like rhipidia; sympodial rachis absent or up to 3 mm long, covered with appressed to ascending, yellowish hairs c. 0.2 mm long; pedicels 4–17 mm long, 0.6–0.8 mm diam, fruiting pedicels 8–35 mm long, 1–1.4 mm diam, indument as on rachis; lower bracts ovate, 1.3–1.8 by 0.6–0.9 mm, indument as on rachis; upper bract in the lower half of the pedicel or halfway, broadly ovate, 0.5–1.2(–4) by 0.9–1.4(–3.9) mm, indument as on sympodial rachis; flower buds globose. Flowers bisexual; sepals free or connate at the base, depressed ovate, 1.5–2.5 by 3.4–4.4 mm, apex rounded to mucronate, densely covered with appressed, yellow hairs, persistent in fruit; receptacle 3–3.5 mm diam, flat; petals colour in vivo unknown, 6, in two whorls, outer petals ovate, 7–8.5 by 5.2–8.4 mm, outside and margins of the inside covered with yellow-brown hairs, inner petals elliptic, 6.6–7 by 3.8–5.2 mm, outside and apical part of the inside covered with yellowish hairs; stamens 24, in three whorls, free, obovoid, c. 1.3 mm long, filaments c. 0.4 mm long, thecae latrorse, connective truncate, prolonged slightly inward and outward or not prolonged, not hiding thecae, glabrous, staminodes absent; carpels 17 or 18, subcylindric, 2–2.3 by 0.4–0.5 mm, glabrous or sparsely covered with few hairs, ovules 4, lateral, stigma elongate, 0.8–1.1 mm long, glabrous. Monocarps 4–8, reddish orange, ellipsoid to narrowly ellipsoid, 11–38 by 6–9 mm, verrucose, sparsely covered with few hairs or glabrous, apex rounded to apiculate, apiculum c. 1 mm long, stipes 3–6 mm long. Seeds 1–4, ellipsoid, 6–8.5 by 4.8–5.2 mm, ochre-brown, apex rounded or flattened, raphe hardly visible.

Distribution — Malawi, Mozambique, Zimbabwe.

Habitat & Ecology — In mixed evergreen forest, gallery forest, dense woodland; on sandy loam soil.Altitude: 396–1500 m. Flowering: October to January; fruiting: January to May.

Vernacular name — Mozambique: Mutadza (E.C. Andrada 1026).

Preliminary IUCN conservation status — Near threatened (NT). EOO: 192 050 km 2, AOO: 96 km 2. This species is known from 13 locations including 3 nature reserves; however, the area of occupancy is quite small and several of the locations are under threat of forest degradation or mining activities.

Note — Monanthotaxis chasei is the only species of Monanthotaxis in Zimbabwe, Malawi and the north of Mozambique with almost glabrous carpels. The yellowish brown, appressed hairs on the young branches and the veins on the lower side of the leaves set it apart from other species of Monanthotaxis with extra-axillary flowers and 24 stamens in three whorls.

Figures

Map 10 Distribution of Monanthotaxis chasei N.Robson (■) and M. maputensis P.H.Hoekstra (●, O means uncertain dets).