Drypetes burnleyae Cheek

Cheek, M., Ndam, N. & Budden, A. Notes on the threatened lowland forests of Mt Cameroon and their endemics including Drypetes burnleyae sp. nov., with a key to species of Drypetes sect. Stipulares (Putranjivaceae). Kew Bull 76, 223–234 (2021). DOI: https:

Type

Cameroon, Southwest Region, on Hunters path to ‘Lake Njonji’, 40 minutes’ walk N then E from Njonji, 4°08’N, 9°01’E, alt. 150 – 300 m, fr., 19 Nov. 1993, Cheek 5490 (holotype: K barcode K000593141, isotypes: BR, K, MO, SCA, WAG, YA).

Morphology General Habit

Dioecious tree or shrub 2.5 – 6 m tall, trunk 4 – 7 cm diam. at 1.5 m from the ground, bark grey

Morphology Reproductive morphology Fruits

Fruiting and flowering from burrs on the leafy stems Fruit ellipsoid, (1.2 –) 1.4 – 1.9 cm long, 0.8 – 0.9 (– 1) cm diam., with 2 opposite shallow longitudinal grooves when dry, completely covered in appressed whitish brown hairs

Morphology Stem

Leafy stems distichous, densely golden hairy completely covering terminal internode of stem apex, rapidly caducous at the internodes below, hairs simple, 0.05 – 0.2 mm long appressed; epidermis below the first node longitudinally furrowed, grey white or white, glossy, often c. 50% covered in micro-epiphytes, lenticels developing from c. fourth internode, white, slightly raised, elliptic 1 – 2 mm long, c. 0.5 – 1 mm wide; internodes even in length 2.1 – 5.8 (– 6.3) cm long, diam. 0.3 – 0.35 cm at the fourth internode from apex, stems slightly flexuose, or terete, with up to 8 leaves per stem

Morphology Leaves

Leaf-blades drying grey-green above, brown below, narrowly oblong-elliptic, rarely slightly oblanceolate-oblong, (19.5 –) 20.5 – 33 (– 40.2) × 6.5 – 11.4 (– 13) cm, acumen 0.4 – 1.1 (– 1.4) cm long, acute, base acute, inconspicuously asymmetric, margin entire, lateral nerves (7 –) 8 – 11 (– 12) on each side of the midrib, drying black, arising at 45° from the midrib, arching upwards distally, then running parallel to the margin and connecting with the secondary nerve above by 3 – 4 brown tertiary nerves, sometimes with a short brown intersecondary nerve present; quaternary nerves brown (concolorous with blade) forming a reticulate pattern, conspicuous on abaxial surface, glabrous

Morphology Leaves Petiole

Petiole drying grey, slightly laterally compressed, adaxial surface slightly and shallowly grooved or not, surface longitudinally wrinkled, (0.7 –) 0.9 – 1.3 × 0.2 cm, glabrous

Morphology Leaves Stipules

Stipules persisting to the fourth node below stem apex, coriaceous, grey-brown, lanceolate or oblong-lanceolate, (7 –) 8 – 10 × (2 –) 3 – 3.5 mm, apex long tapering, acute, margins revolute, surface finely longitudinally furrowed, indumentum as stem apices

Morphology Reproductive morphology Inflorescences Bracts

Bracts concave, brown, ovate-elliptic 1.5 – 1.75 mm long 1 – 1.25 mm wide, apex acute, completely covered in appressed, yellow-brown hairs, hairs simple, 0.125 – 0.175 mm long; bracteoles triangular, 0.75 – 1 mm long and wide, indumentum as bracts

sex Female

Female flower “with pale yellow ovary and narrow white annular disc” (Thomas 9710), 5 – 7.5 mm long, 3.2 – 3.5 mm wide, pedicel 1.5 – 2 mm long, 0.8 – 1 mm diam., indumentum as bracts Female inflorescences in axillary fascicles subtended by the most distal (oldest) leaves from the apex or sometimes at leafless nodes, 1 – 8-flowered, each flower subtended by a bract and pair of bracteoles

Disc

Disc protruding beneath ovary by 0.25 mm, 1.25 mm high, rounded, entire, glabrous Disc flat, glabrous, rounded-quadrangular 1.75 mm diam., each of the 4 edges with a shallow notch (accommodating an anther filament), upper surface with raised coarse reticulations, cells c. 0.2 – 0.3 mm diam. Rudimentary ovary absent

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary ovoid 5.5 – 6 mm long, 4.7 – 6 mm wide, lacking grooves, completely covered in appressed yellow-brown hairs c. 0.25 mm long; 2-locular

Morphology Reproductive morphology Flowers Gynoecium Stigma

Stigmas 2, black, sessile, parallel, transversely oblong-ellipsoid, 0.8 – 0.9 mm long, 1 – 1.25 mm wide Stigmas persistent, not accrescent

sex Male

Male inflorescences as the female, 1 – 7-flowered Male flowers “Calyx light green” (Tchouto 687) 4 – 4.5 mm long, 2.5 – 3 mm wide at anthesis, opening from globose buds

Morphology Reproductive morphology Flowers Pedicel

Pedicel 1.5 – 2 mm long, 0.5 – 0.7 mm diam., indumentum as in females Pedicel accrescent (0.15 –) 0.2 – 0.4 cm long

Morphology Reproductive morphology Flowers Calyx

Outer sepals 2, concave, ovate-elliptic, 3.5 – 4 mm long, 4 mm wide, apex rounded, indumentum as females covering 20 – 70% of surface Inner sepals 2, ovate-elliptic, 5.5 mm long, 4.8 – 5.5 mm wide, apex and indumentum as outer sepals Outer sepals 2, concave, elliptical 3.5 – 4 mm long, 2.8 – 3.8 mm wide, apex rounded, outer and inner surface densely covered (90 – 100% of epidermis covered) in indumentum as in the bracts, but hairs 0.25 mm long Inner sepals 2, orbicular 3 mm long, 3 mm wide, indumentum as in females, 90% cover

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 4, not exserted, 1 – 1.4 mm long, filaments stout, 0.4 mm long, glabrous, anthers orbicular, 1 mm long, 1 mm wide, dorsal face flattened, ventral with 4 longitudinal thecae, apex rounded, apex with 2 – 3 tufts of hairs 0.5 mm long, margin fringed with hairs

Morphology Reproductive morphology Flowers Corolla

Sepals persistent, not accrescent

Morphology Reproductive morphology Seeds

Seeds 2, one per locule, dark brown, plano-convex, 16 mm long, 10 mm wide, 6 mm broad, lacking surface ornamentation.

Distribution

Cameroon, South West Region (Map 1). So far only known from coastal forest of Mt Cameroon.

Ecology

Infrequent small tree or shrub of undisturbed lowland evergreen forest on old volcanic or pre-Cambrian rocky soils; 50 – 300 m alt.

Conservation

Drypetes burnleyae has an extent of occurrence of 94 km2 and area of occupancy of 32 km2 as calculated using GeoCAT (Bachman et al. 2011). There are only three “threat-based” locations (IUCN 2012), in the Onge forest and the Bomana-Njonji forest. These areas of Mount Cameroon are threatened with forest clearance, both for timber and oil palm. Species within the genus Drypetes are slow growing trees and shrubs and are indicators of good quality, undisturbed forest. They do not regenerate well after major forest disturbance and are therefore especially sensitive to the threats posed by forest clearance. Given the threats and restricted range, an assessment of Endangered (EN B1+2ab(iii)) is given to this species.

Etymology

Named in honour of Mrs Gwendoline Etonde Burnley (1932 — 2020) of Limbe (formerly Victoria), the first anglophone female MP of Cameroon, and UN delegate for Cameroon. She championed the cause of restoring the Limbe Botanic Gardens as part of the UK Government-supported Mount Cameroon Project that sought to protect the world-renowned plant diversity of Mt Cameroon. Until recently, she was Chair of the Friends of the Limbe Botanic Garden.