Stangeria eriopus – Kunze (1839)
Stangeria (Eng), Stangeria, Bobbejaankos (Afr)
Stangeria eriopus is a small cycad species with stems completely subterranean and a root shaped like a carrot. The underground part can be 100mm up to 250mm in diameter. Stangeria is a perennial plant and often branches into several growing points. Branching occurs in the stem portion and not the root. The root makes up most of the subterranean part and only the apical part is considered to be the stem. The transition from root to stem is not readily detectable according to Dyer (1966). The apex produces woolly scales but these are shed early. As in other cycads, S. eriopus also forms corralloid roots. These roots may play a part in the aeration of the roots (more pronounced in badly aerated soils) but it has been showed that the symbiotic bacteria found in these roots, facillitates nitrogen fixation. Two species have been identified, namely Bacillus radicola and Azotobacter sp.
Leaves are formed one at a time at each growing point. The new leaves have an inflexed ptyxis and young leaves appear to be rolled up at the tip. The leaves are covered by short, grey hair but this disappears soon, except at the base of the petiole. The leaves are pinnate and vary in lenght from 250mm to 2m depending on the environment. The petiole makes up half of this length.
The pinnae are soft to leathery and varies in texture and size. They are arranged in 5 to 20 opposite or almost opposite pairs. The lower pinnae have stalks but the upper ones are fused at the base. The venation of the pinnae are considered primitive and resembles that of ferns. The pinnae have a prominent midrib with faint lateral veins branching out. The veins fork at least once near it origin and sometimes 2 or 3 times more.
Stangeria has stalked cones as reproductive organs with male and female cones borne on different plants. S. eriopus appears to bear a single cone per growing point and herbarium data suggests coning takes place throughout the year. The male cone is cylindrical and tapers to the apex. The young cones are covered with short, silvery hair which falls off when the cone matures. The cone then displays a yellow-brown colour. Male strobili are about 30mm to 40mm in diameter and 100mm to 250mm long. Microsporophylls are spirally arranged around the axis of the cone and triangular or rhomboid as seen from above. They are ± 12mm wide and long and the outer face ± 12mm wide and 4mm to 6mm high. Each microsporophyll bears about 150 microsporangia (Chamberlain 1919) on the lower surface in groups of 3 to 6. When a male cone is mature, it elongates along the central axis and this separates the microsporophylls from each other to release the pollen.
The female strobilus is elliptic or cone shaped with a rounded apex. Young cones are covered with silvery hair but this is lost and colour is then dark green when mature. Length is up to 180mm and diameter 80mm. The macrosporophylls are also spirally arranged, but in such a way that the outer faces appear to be arranged in six vertical columns. They are about 60mm wide and long with the outer scale face up to 40mm high. The outer surface is slightly convex and overlaps the scales above it. Two ovules are borne at the base of the macrosporophyll and are up to 35mm long and 25mm wide. When the female cone is mature, the macrosporophylls also separate. The micropyle secretes a drop of sticky fluid and pollen falling on it is retained. When the fluid evaporates the pollen is drawn into the ovule and fertilization takes place. The cone disintegrates eventually and seeds fall to the ground. The sarcotesta covering the sclerotesta is dark red. The latter measures about 20mm in lenght by 14mm wide and is stained pink by the sarcotesta. This changes to brown when exposed to the atmosphere.
Distribution & Habitat
This species is restricted to coastal areas on the east coast of South Africa from Bathhurst to the border with Moçambique. It is found within 50km, but not closer than 2km to 3km from the sea. It does not seem to tolerate saltspray and occurs only occasionally in the grassland of the first coastal dunes where it is sheltered from any spray. It grows in full sun in the grassland, partial shade in the coastal parkland and in the dense shade of coastal forrest. The soil is mostly sandy and derived from sandstone. In the north Stangeria occurs on granite soils and in the Transkei plants were observed on heavy black clay. Soils are slightly acidic. Rainfall occurs mostly in summer and is more than 1000mm in the north, falling to less than 750mm in the southern part of the distribution. Frost occurs rarely.
Cultivation & Propagation
S. eriopus is easy to grow and plants in cultivation are usually more attractive than in the wild. It is usually advisable to let wounds dry out before replanting cycads but for Stangeria it is better to dust the wounds with a fungicide or sulpur, then wrap it in plastic to prevent desiccation until it can be planted again. Leaves should be left on the plant and not removed, unless they die. Stangeria is best grown in shade for more luxuriant foliage. They prefer sandy, acidic soils, rich in organic material. A layer of mulch is also advantageous to keep the tuber covered and prevent the soil from drying out. True to cycad nature, growing plants from seed is slow. It appears that the sarcotesta inhibit germination, probably chemically, and it is advisable to remove it. To germinate seed, use a light, sandy, humus rich soil, press the seeds halfway into the soils with the long axis parallel to the surface. Never cover the seed with soil and preferably put the seed bed under glass to keep the air humid inside. Keep it in the shade. When the radicle appears the seeds can be potted individually to prevent damage to the taproot, which is already well developed by the time leaves appear.
S. eriopus was at first misidentified by Kunze as the fern Lomaria coriacea and later, still incorrectly, described as Lomaria eriopus, probably because of the inflexed vernation, 'primitive' venation of the pinnae and the general appearance of the leaves. Male and female strobili were unknown then and the mistake was only rectified when live material was collected by Dr. Max Stanger (the genus Stangeria was named after him) in 1851 and sent to England. When this plant produced cones, it was named Stangeria paradoxa by Moore, refering to the paradoxal nature of the plant as being either a 'fern-like Zamia or a Zamia-like fern'. However, the specific epithet, eriopus, was validly published for this taxon and the correct name is Stangeria eriopus. The specific epithet means 'woolly', but this probably refers to the velvety hair, covering the leaf when it appears. The cones, which have the same covering, was unknown when the name was proposed by Kunze.