Olinia huillensis subsp. burttdavii Sebola

Sebola, R.J. & Balkwill, K. 2013. A monographic study of the Oliniaceae. Kew Bulletin 68: 419. https://doi.org/10.1007/s12225-013-9465-x

Type

Type: South Africa, Mpumalanga Province, Graskop district, The Pinnacle, Sebola 225 (holotype J! isotypes BM!, K! & PRE!).

Morphology General Habit

Shrubs up to 3 m high

Morphology General Bark

Bark and stems dark-grey branchlets grey, distinctly quadrangular, thick with short internodes

Morphology Leaves

Leaves 30 – 53 × 19 – 31 mm, obovate, coriaceous, glabrous on both surfaces margins with a tinge of red base cuneate apex often incised, recurved and slanted to one side of blade becoming deeply emarginate Primary veins conspicuous above Secondary veins conspicuous below, loop twice before margins

Morphology Leaves Petiole

Petiole short, reddish, sparsely pubescent above, 1.5 – 2 mm long

Morphology Reproductive morphology Inflorescences

Inflorescence units compact axes thick, distinctly quadrangular

Morphology Reproductive morphology Inflorescences Bracts

Bracts caducous

Morphology Reproductive morphology Flowers

Flower 5-merous

Morphology Reproductive morphology Flowers Pedicel

Pedicel slightly glaucous, very short, 0.5 – 1 mm long

Morphology Reproductive morphology Flowers Hypanthium

Hypanthium broad and thick-walled, glabrous, up to 12 mm long

Morphology Reproductive morphology Flowers Calyx

Sepals as for the genus

Morphology Reproductive morphology Flowers Corolla

Petals spathulate to slightly oblong, apiculate, thickly textured, glabrous on both surfaces, pink and turning red at maturity, 5 – 7 mm long

Morphology General Scales

Scales markedly pubescent and often yellowish, 2.5 – 3 × 3 mm

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens as for the genus

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary 5-locular style slightly pubescent, 2 – 4 mm long stigma capitate

Morphology Reproductive morphology Fruits

Fruit pink, becoming red when mature, ovoid, 10 – 14 mm in diam., apex marked by hypanthium scar/rim 5 – 7 mm in diam.

Ecology

The plants tend to occur on windswept rocky outcrops in montane grassland, or mist-prone environments at high altitudes alt. 1475 – 2500 m.

Conservation

The distribution is restricted to Mpumalanga, South Africa where it overlaps with that of subsp. huillensis. Its extent of occurrence is approximately 2683 km2, mainly in nature conservation areas, where there are no apparent threats to its habitat due to human activities (development and agricultural practices, pers. obs.). Since 1997 there has been no visible destruction to habitats or reduction of population sizes. However, information on the numbers of individuals per locality and the number of localities appears limited, and more data is desirable. It is thus assessed as Data Deficient (DD).

Phenology

Flowers from Oct./Nov. fruits set from April/May.

Note

The epithet burttdavii honours the late Joseph Burtt Davy, an important plant collector in the Transvaal province (now split into Mpumalanga and Limpopo province) of South Africa and Swaziland who first recognised this taxon as distinct. Subsp. burttdavii is readily separable from other subspecies of Olinia huillensis by having branches that are distinctly quadrangular and thick with shorter internodes. Inflorescence units are shorter than the axes and the hypanthia are glabrous, robust, strong, deep red and short relative to petal lengths. This is in contrast to subsp. huillensis with inflorescence units longer than the axes, hypanthia that are creamy white to slightly pink, weak and narrow and twice as long as the petal lobes. Subspecies burttdavii differs from O. usambarensis, with which it was confused (Burtt Davy 1926), by its shorter obovate leaves and thickly textured and glabrous hypanthia. This subspecies differs from the other two by its habit, either shrubby or a small tree measuring below 2.5 m high, and often multi-stemmed with stout terminal branches. Leaves are coriaceous with a tinge of red on margins.