Ochna stolzii Gilg ex Engl. (Engler 1921: 480)

Shah, Toral, Mashimba, Fandey H., Suleiman, Haji. O., Mbailwa, Yahya S., Savolainen, Vincent, Larridon, Isabel & Darbyshire, Iain, 2023, A taxonomic revision of the ecologically important Ochna holstii (Ochnaceae) complex using molecular and morphological data, Plant Ecology and Evolution 156 (2), pp. 174-200 : 174

2. Ochna stolzii Gilg ex Engl. (Engler 1921: 480)

Figs 2A , 4C , 7

Type.

TANZANIA • Station Kyimbila; 1913; Stolz 2212; holotype: B†; lectotype (designated here): M [M0109480]; isolectotypes: G [00341181], JE [JE00002320], S [S08-21470], U [U0283523], WAG [WAG0002472].

Description.

Shrub or suffrutex 0.4-1.8(-2) m tall. Bark smooth grey to brown. Stems brown to purple, glabrous, sometimes with white lenticels and often flaking off; young new growth brown and densely puberulous. Stipules brown, linear, semi-persistent, 3.5-4 cm long. Leaves green, drying blue-black above and brown below or brown throughout, slightly coriaceous, glabrous, small, elliptic to obovate or sometimes lanceolate, 1-4.5 cm long, 0.5-2 cm wide; leaf base cuneate, acute to rounded or sometimes attenuate at the apex, margins spinulose-serrate; lateral veins 15-20, ± prominent on both sides, tertiary vernation reticulate above and below, midrib raised on both sides; petiole obsolete or up to 1.5 mm long; buds small brown, glabrous, bud scales deciduous, up to 4.5 mm long; annual shoot scales deciduous, 3.5-4 mm long sometimes up to 1.5 cm long. Flowers solitary or arranged in fascicles with up to 4 flowers, or in racemes with 3-6 flowers; rachis 0.5-2.5 mm long, often puberulous; pedicels 1-2.5 cm long, articulated at or near the base, or up to 2.5 mm, glabrous or slightly puberulous. Sepals green to brown, elliptic, 7-9 mm long, 5-7 mm wide in flower, turning carmine red in fruit, 7-19 mm long, 6.5-10 mm wide. Petals yellow, obovate, 9-11.5 mm long, 5.5-8.5 mm wide. Anthers dehiscing by longitudinal slits, 1.5-1.8 mm long; filaments longer than anthers, 2-3 mm long. Carpels 5; styles united at apex, 5-7 mm long. Drupelets black, ellipsoid, 10-13 mm long, up to 1 cm wide, attached at the base.

Distribution.

Tanzania and Mala wi (Fig. 7 ).

Habitat.

Upland and montane grassland, rocky outcrops, and upland Brachystegia woodlands. Altitude: 1525-2400 m.

Phenology.

Mostly flowering and fruiting from November to February, which corresponds to the short rainfall season (November and mid-January) in Tanzania and the hot and rainy season occurring (November and April) in Malawi.

Preliminary IUCN conservation assessment.

Ochna stolzii has an estimated EOO of 58,579 km2 and an AOO of 80 km2. The species faces threats of habitat destruction in parts of its range. For example, many of the montane grasslands of the Njombe area have been converted to rangeland or extensive timber plantations. This is a growing threat to the Sao Hill occurrence in the Mufundi area as well. With its restricted range and only being known from 10 locations, with the ongoing threat of habitat destruction, the species is therefore assessed as Vulnerable: VU B2ab(ii,iii).

Additional material examined.

TANZANIA - Njombe District • Stromgebiet des oberen Ruhudje; 1931; fr.; Schlieben 1140A; K [K001383210] • Njombe ; Oct. 1931; fl.; Staples 190; K [K001383206] • Njombe ; 10 Dec. 1931; fr.; Lynes DK 93; K [K001383204] • Msima Stock Farm ; 1932; fr.; Emson 387; EA, K [K001082550] • Msima Stock Farm ; 1932; fr.; Emson 241; EA, K [K001082553] • Rugauga , south, Highlands club; 19 Jan. 1952; fr.; Wigg 999; K [K001383201] • Idunduge ; Nov. 1953; fr.; Carmichael 314; EA, K [K001383203] • Njombe-Milo Rd. ; 1950 m; 28 Jan. 1961; fr.; Richards 14019; K [K001383208] . - Iringa District • Dabaga ; 7 Feb. 1932; fr.; Lynes 12; K [K001383157] . - Mufindi District • Sao Hill; Dec. 1963; fr.; Proctor 2466; K [K001383199] • Mufindi tea estates, near Ngwazi lake ; 1850 m; 20 Nov. 1986; fr.; Brummit & Mwasumbi 18072; K [K001383198] • Lake Ngwazi ; 8°31'S, 35°09'E; 1850 m; 28 Mar. 1991; fr.; Bidgood & Vollesen 2157; K [K001271359] • Mafinga-Mufindi 23 km; 8°24 ’0.00” S, 35°28 ’40.08” E; 1900 m; 9 Nov. 2008 fr.; Luke 12770; K [K001383197] .

MALAWI - Chitipa District • Near the top of the Mafinga Mts, above Chisenga ; 22 Nov. 1952; Angus 839; K [K001387712] . - Rumphi District • Nyika Plateau, 2 miles from Zambia Rest House; 2250m; 14 Nov. 1967; Richards 22529; K [K001387711] • Nyika Plateau , Chelenda Bridge and River ; 21 Nov. 1967; fr.; Richards 22670; K [K001387786] • Nyika Plateau , Chowo grassland; 27 Dec. 1975; fr.; Phillips 745; K [K001387714] • Nyika Plateau , edge Fingira Rock ; 5 Nov. 1977; fr.; Pawek 13177; K [K001387713] • Nyika Plateau ; 5 Nov. 1977; fr.; Pawek 13184; K [K001387783] • Nyika Plateau ; 3 Jan. 1977; fr.; Pawek 12240; K [K001387785] • Nyika Plateau , Chowo Rocks ; 2200 m; 11 Jan. 1983; fr.; Dowsett-Lemaire 561; K [K001387784] • Nyika national park , near Chirinda falls , between Chelinda and Chirinda; 10°37'S, 33°50'E; 2400 m; 13 Dec. 1983; fr.; Kruif 1330; K [K001271505] .

Bibliography.

Gilg (1925: 68); Sleumer (1934: 69); Robson (1963: 241); Verdcourt (2005: 25).

Notes.

By its leaf shape and inflorescence arrangement, O. stolzii most closely resembles O. oxyphylla , differing by its suffrutescent habit (0.4-1.8 m tall) and small leaves, being a small or dwarf shrub 0.4-1.8 m tall. It also differs in habitat, with O. stolzii found on grasslands, woodlands and rocky outcrops, whereas O. oxyphylla is only found in forests. Banda 764 and White 2806 from Nikya Plateau, Malawi, could be O. stolzii although the plants are slightly larger, up to 3.5 m tall, and the young stems are glabrous.

Figures

Figure 2. Species of Ochna, habit and leaf margin. A. Ochna stolzii (from Richards 22529). B. Ochna oxyphylla (from Carmichael 354). C - D. Ochna holstii (C from Maas Geesteranus 4971, D from Pierlot 1731). Drawn by Andrew Brown.

Figure 4. Dissection of rehydrated drupelets shows that there are no distinguishing morphological characters in the embryo of any of the mentioned taxa, particularly separating Ochna holstii I and II. A. Ochna holstii II. B. Ochna holstii I. C. Ochna stolzii. D. Ochna oxyphylla.

Figure 7. Distribution map of Ochna stolzii in Tanzania and northern Malawi.