|
Description
The stem is well-developed and often suckering from the base. It can be up to 2m long and 250mm to 400mm in diameter. Older stems are mostly leaning or procumbent when longer than one meter.
The leaves are strongly glaucous ("blue"), straight but not very rigid and sometimes spirally rotated around the axis to give the plant a rather untidy appearance. The petiole is about 120mm long, and the complete frond about 800mm.
The pinnae are directed towards the apex of the frond at an angle of about 45° with the rachis, with opposing leaflets set at an angle of about 90° to each other. The basal leaflets do not overlap, but the median and apical leaflets overlap so that the upper margins of the lower leaflets cover the lower margins of the leaflets in the direction of the apex of the frond, as seen from above. The lower leaflets are not, or only slightly, reduced in size towards the base of the frond. The median leaflets are very narrowly elliptic and slightly curved, tapering to both ends with the apices spinescent, the margins in mature plants having no spines, up to 170mm long and 10mm to 12mm wide.
The male and female cones are very different in outward appearance. They are olive-green, and at a first glance they appear to be hairless, but when the cone scales separate when the cones fall apart, a dense hair coat around the margins of the scales become visible. In mature plants up to three male cones per stem have been recorded. These are very narrowly egg-shaped, 300mm to 400mm long and 60mm to 100mm in diameter, carried on a stalk which is about 80mm long. The faces of the scales are drawn out into a conspicuous lip. Up to three female cones per stem have been seen. These are egg-shaped, 300mm to 450mm long and 180mm to 250mm in diameter, apparently sessile but with an 80mm long stalk hidden amongst the scale leaves at the apex of the stem. Characteristically the female scale faces are conspicuously warty.
|
|
Distribution & Habitat
E. dolomiticus occurs (or perhaps more correctly, occurred) in the eastern Transvaal Drakensberg, where it is known from only a few sites. Here it was recorded in extremely rugged terrain. It was found it in short grassland with scattered small trees, apparently always associated with dolomite outcrops, hence the specific epithet. There are no climatological data for this remote region, but judging from the vegetation the annual rainfall probably amounts to 600mm to 800mm, and occasional frost may occur in winter.
Cultivation & Propagation
Very little information is available, but is seems as if this species is not a vigorous grower. Coming from a dry area, it is probably sensitive to over-watering, and transplantation either from the wild or from one garden situation to another is likely to be hazardous. It should always get as much direct sunlight as possible.
|
|
Notes
The existence of this species has been suspected since the early 1970's, but information was so slow in coming forth that it was only described in 1988. This spesies remains extremely poorly known and it is unlikely that we will ever learn much about it, as it has practically been eliminated in nature. Those specimens which survived removal are scattered through private collections, often without any data about their origin, and often not recognized for what they are, because in the vegetative state this species is without strong distinguishing characteristics.
It seems likely that material of this species was first collected by private collectors, active in what was at that time virtually unexplored Transvaal Drakensberg. Allerted by what they found, the area was subsequently visited by officers of the then Transvaal Division of Nature Conservation. They were responsible for most of the extant herbarium specimens and photographs of plants in nature. At first these plants were thought to represent an outlying form of Encephalaltos eugene-maraisii, probably because of the glaucous fronds and geographical location. Once the cones were studied, it became clear that a distinct species was involved. As part of the so-called E. eugene-maraisii complex, this species was studied in detail during the mid-seventies. Research continued, but the species was not published as a new species because the available information was so meagre. In 1988 E. verrucosus was published by Robbertse, Vorster & Van Der Westhuizen, but was pre-empted by a paper by Lavranos & Goode which appeared a few months before. E. dolomiticus thus has nomenclatural priority according to the International Code of Botanical Nomenclature and E. verrucosus is synonymous.
On account of its stiff, glaucous fronds with spinescent leaflet apices, E. dolomiticus resembles not only E. eugene-maraisii, but also E. dyerianus, E. lehmannii, E. middelburgensis, E. princeps, and to some extent E. cupidus. There are, however, profound differences between the species:
- Both E. dyerianus and E. cupidus are readily distinguished from E. dolomiticus by their very short or absent leafstalks, smooth female cone scale faces, and their male cone scale faces which are not drawn out into drooping lips.
- It differs from E. middelburgensis by its egg-shaped rather than cylindrical female cones of which the scale faces are warty instead of smooth.
- E. eugene-maraisii and E. lehmannii differ from E. dolomiticus by their female cone scale faces having smooth faces, overlain to a greater or lesser extent with russet-brown hairs.
- The resemblance between E. princeps and E. dolomiticus is superficially much closer, both in the egg-like shape of the female cones and the warty surfaces of the female cone scales. The male cones of these two species also show some resemblance in that the scale faces are drawn out into a drooping structure, but in E. princeps it is a beak-like rather than a lip-like structure.
Collectors often claim that this species can be distinguished by its spirally twisted fronds, but this is not a feature of all plants. It seems as if this species never was plentiful, and that collecting has reduced it to near or complete extinction in nature. Clearly this is an example of a species fighting for survival. The plants are much too valuable to be in private hands, scattered over the country and perhaps even abroad. Its only hope for survival is that all identified specimens should be brought together under the care of a body such as the National Botanical Institute, where a controlled breeding programme could be set up.
|