Encephalartos inopinus – Dyer (1964)

Lydenburg Cycad (Eng), Lydenburg Broodboom (Afr)

Category: Threatened and Protected

 

Description


The stems of mature Encephalartos inopinus plants are slender in diameter, about 15cm to 25cm, and variable in length up to about 3m. However, very old multi-stemmed plants, like those in the Olifants River krantzes, become procumbent and can reach as much as 4.5m in length. The trunks sucker relatively freely. The stem is very characteristic with the different size leafbases resulting in a “patchwork” pattern.

The leaves of E. inopinus is a fresh bluish-green colour and has a silvery bloom. Leaves are typically about 0.8m to 1.5m long, depending somewhat on the degree of sunlight or shade to which the plant is exposed. The rachis is characteristically yellowish-green, more-or-less straight, but quite often with some upwards curvature and a slight twist towards the apex. In most specimens the leaves exhibit a pronounced bare petiolar section, up to about 20cm in length. However, a lesser number of plants have leaflets which reduce progressively in size towards the leafbase and consequently have a much shorter petiole.

Although teeth are normally absent from the pinnae margins, occasionally minute teeth are found on the lower leaflet margins towards the apex. Leaflets are typically about 14cm to 20cm long and 8mm to 12mm wide. The fairly widely-spaced leaflets bend gracefully down under their own weight from the rachis so as to give a gentle inverted “V” appearance, a characteristic which adds much to its overall form. This inverted “V” leaflet arrangement is uncommon in the genus, with the only other species showing this being E. heenanii, E. paucidentatus, E. ghellinckii and, to some extent, E. cycadifolius.

Male plants of E. inopinus bear, somewhat sporadically, up to 4 silvery green, rather pointed, cones. The cones measure about 18cm to 25cm in length by 6cm to 8cm at their widest diameter and have a peduncle of up to 10cm long. Pollen is shed somewhat earlier in the year compared to other species, typically in February. The female plants bear, also somewhat sporadically, 1 to 3, barrel-shaped, greenish-yellow cones with a whitish bloom. The cones are about 30cm to 35cm long by about 15cm to 20cm in diameter. Female cones have a very short, stout peduncle completely surrounded by the bracts arising from the stem apex. Cone scales are somewhat unusual in being more-or-less the same size throughout the cone with only the few smaller sterile apical scales being smaller. The cone bulla and facet surfaces give a striking geometrical appearance to the structure as a whole. Seeds, which are shed some 6 months after pollination (i.e. about August), are pale orange in colour. They measure about 4cm x 2.7cm with the seed kernel having dimensions of 3.2cm x 2.0cm.

Female cones

Male cones

Leaf detail

Distribution & Habitat


E. inopinus occurs very sparsely, mainly in thick bush on north-facing steep slopes or rocky outcrops in the generally rugged terrain of the Olifants River catchment area. The climate is simply “hot” and the rainfall ranges from a meagre 375mm to 750mm annually. Goode reports that only the occasional plant is tall enough to protrude through the bush cover but that there are some particularly fine specimens, with up to eight stems, hanging from inaccessible narrow ledges high up in one of the gorges.
Cultivation & Propagation


There is little information available on the optimum conditions for garden cultivation of E. inopinus. Based on observations, it is suggested that, like so many of the members of the genus, a semi-shady position with good drainage would be most appropriate. Care should be taken when removing basal suckers to avoid rot setting in to either the parent plant or the suckers. This species can also be propagated by seed but the sporadic coning makes that difficult.

 

Notes


In 1955 the attention of a group of hikers in the Transvaal’s Lydenburg district was caught by an unusual looking plant. One of the group, Dr Helmoed van Hoepen, removed a sucker from this specimen and replanted it in his Johannesburg garden. Here it flourished, but it was not until nine years later that it attracted the interest of botanists. In an effort to relocate the parent plant, a Mr. C.A. Els, also a member of the original hiking group, set off in August 1964 with Dr L.E. Codd, Dr I.C. Verdoorn, Mrs. E. van Hoepen and Dr R.A. Dyer. Unfortunately the original plant appeared to have perished, but a second specimen was found on a nearby sheer krantz along the Steelpoort River between Penge and the Kromellenboog asbestos mine. A local from the area told the party that there were three more plants in mountainous territory a little further to the east. At that time, Drs Dyer and Verdoorn had been hard at work on their cycad survey and believed they had seen all possible species. This new finding, described enthusiastically by Dyer as “one of the major botanical discoveries in South Africa in recent times”, was thus something of an “unexpected” bonus.

By curious coincidence, the farm on which the new plant was found, was called “Onverwacht” (“unexpected”) and it was thus a natural choice for Dr Dyer to latinize the epithet in his 1964 description of Encephalartos inopinus. The botanical description was published without its author having seen any cone material, apart from two damaged young male cones. In 1969, a Transvaal Nature Conservation officer was fortunate enough to find a new but scattered colony of E. inopinus. He was able to bring a female cone back for Dr Dyer’s inspection. Male cone material was also provided and, with this new evidence, Dr Dyer was able to complete the botanical description for the species in 1971.

In times before cycad collecting was fashionable, E. dolomiticus and E. inopinus grew in near proximity in habitat. However, no natural hybrids of these two species, or with any other species, have been recorded.

As with many Encephalartos species, the habitat population of E. inopinus has suffered much from the activities of collectors. In addition, Douglas Goode maintains that large troops of baboons in the area frequently damage the immature cones and that this possibly explains the absence of seedlings. In terms of the Threatened Plant Unit’s listing, E. inopinus is described as “endangered”, sharing this unfortunate status with many other species.