Encephalartos aplanatus – Vorster (1996)

Encephalartos aplanatus (scientific name)

*updated 18.10.2017

 

Description


Encephalartos aplanatus lacks aerial stems and has a mostly subterranean habit. Plants are solitary with an exposed apex. Branching or suckering does not occurs as is the case with E. villosus.

The plant has few leaves, 2-6 normally, with occasionally 8 per plant. Young leaves are erect and arching but becomes almost horizontal with age. Young leaves are covered in fine hair but this is lost as the leaves get older. Leaves can grow to 3.5m long with a petiole of 200mm. The petiole and lower rachis is covered in a whitish indumentum.

The pinnae are directed towards the apex and opposing leaflets are inserted at 180 degrees to each other. The lower pinnae are progressively reduced to prickles. Median pinnae are narrowly ovate, tapers to an acute but not pungent tip with both margins sparsely dentate, very rarely entire. Median pinnae are up to 300mm long, 40mm wide and dark glossy green in colour.

Pollen cones number up to 3 per plant. They are up to 650mm long, 80mm to 100mm in diameter and the peduncle can be up to 220mm long. The male strobili emerge green but turn a pale yellow when mature. The exposed part of microsporophylls are flat, smooth and hairless. A female plant bears one or two cones. They can be up to 400mm long and 120mm in diameter. Peduncles are stout and up to 60mm long. The exposed faces of megasporophylls are flat, smooth and also hairless, like the microsporophylls. The facets are indistinct with sharp abaxial ridges. The cones appear in January, mid summer, pollen is shed in mid autumn and the female cones disintegrate in early to mid Spring. Seeds are ellipsoid, about 25mm long and 13mm to 15mm in diameter. The sarcotesta is bright red.

Female cone

Male cone

Leaf detail

Distribution & Habitat


The species is endemic to, and occurs only in a small area in the north eastern part of Swaziland. It occurs in the shade of deciduous, fairly dry ravine forest. It is not known to occur with E. villosus or E. umbeluziensis. On a field expedition by the author of the taxon, only one colony was found and plants were scattered and not very healthy. Searching known localities where the species occurred in the 1940’s also proved to be fruitless. It is possible that E. aplanatus was never abundant in the wild and to compound matters, the species has been collected to near extinction.

 

Cultivation & Propagation


E. aplanatus can be treated much the same as E. villosus given that the two species are closely related and have a similar habitat. They like shade and well drained soils. Propagation is by seed. Unlike E. villosus, E. aplanatus does not sucker to form clumps.

 

Notes


E. aplanatus was figured under E. villosus by Dyer (1947) until it was described as a distinct species by Vorster. The two species have nearly identical cones, the same acaulescent habit and small number of leaves, 6-10 only. It is differentiated solely on vegetative characteristics instead of differences in the reproductive structures. The leaves are longer, 3,5m as opposed to 2,5m in E. villosus, often shortly petiolate instead of sessile and pinnae are larger, more dentate and the margins are twisted out of plane or undulate.

Recent research found two related but distinct species of Porthetes beetles present in both E. aplanatus and E. villosus cones. These species are restricted to their specific host cycad species and may provide additional support for the recognition of E. aplanatus. Since the closest occurrence of E. villosus is 100km away, E. aplanatus is not considered to be a hybrid involving that species.