Encephalartos horridus – Jacquin (1801)

Eastern Cape Blue Cycad (Eng), xxx Broodboom (Afr)

Category: Endangered

 

Description


The stems of typical, mature Encephalartos horridus plants are between 50cm and 1m in length and 20cm to 30cm in diameter. When grown in deep soil, the bottom half or more of the stem may be covered by soil, creating the impression that E. horridus is a dwarf species. In more rocky areas, the stems may be entirely above ground level. The entire crown of the stem is slightly woolly. E. horridus forms thick, tuberous roots and even small seedlings have large roots, appearing out of proportion with the stem and leaves. Many of these tuberous roots may be formed, especially if the original tap root is broken off or damaged. Plants may be unbranched but are more usually branched from the base. Large clusters of plants may be formed.

The very characteristic leaves of E. horridus, for which the species is named, are approximately 1m long and usually sharply recurved towards the tip. Younger leaves have a very attractive silvery-blue colour but turn green with age. The petiole is up to 15cm in length and the leaf base is large and light-brown in colour.

The pinnae at the middle of the leaf are approximately 10cm long and 2,5cm broad. In drier, less fertile areas the leaflets tend to be narrower and the leaf less recurved at the tip. Each leaflet has two or three prominent lobes on the lower margin, up to 4cm in length. These lobes are twisted out of the plane of the leaflet, giving the leaves a dense appearance. The leaflets are fairly widely spread towards the base of the stem. Those near the base are smaller and may be entire, but are not reduced to more than one prickle. Towards the tip of the leaf the leaflets are more closely spaced and forms an even regular pattern, especially in plants growing in more fertile soil. The tips of the leaflets and lobes are very sharp and thorn-like.

Single cones are usually formed, although male and female plants with two cones have been observed. The cones have a brownish- or blackish-red colour, due to a dense layer of fine hair on the cone scales. In older cones the hair wears off and the cones appear more green in colour. Male and female cones are supported by a short, thick peduncle, approximately 8cm long and 3cm in diameter. The male cone is cylindrical in shape but narrower at the ends than in the middle. It is up to 40cm long and up to 12cm in diameter. The cone scale is 3cm to 4cm long and approximately 3cm broad, with a relatively smooth face. The face of the cone scale at the middle of the cone forms a beak up to 1cm long. There are usually about 15 spirals of scales. The female cone is egg-shaped and up to 40cm long and up to 20cm in diameter. The cone scale is approximately 5cm long, 5cm wide and 3cm high. The face of cone scales at the middle of the cone protrudes about 2cm and is ridged towards the tip. The scale face is fairly smooth. There are usually 8 to 10 spirals of scales. The seeds are pale red to carmine in colour and are approximately 3,5cm long and 2,5cm in diameter. The seeds tend to be roughly triangular with three flattened surfaces.

Some variation occurs within the species. In the Port Elizabeth district, to the west and north of the city, plants have been found which are in all respects smaller than the “normal” E. horridus found in the Uitenhage district. Some uncertainty still exists about the status of this “dwarf” form. The first of these smaller plants were found on a quartzite hill with sparse, sour vegetation. This different habitat gave rise to the possibility that the dwarf nature of these plants was the result of the poorer soil conditions. There have subsequently been reports of dwarf plants originating from areas where the conditions are closer to those in the fertile Uitenhage area.

The dwarf plants seem to differ from the typical specimens of E. horridus in the following ways:

    • The stems of mature plants are only up to approximately 20cm high and up to 15cm in diameter.
    • The plants branch more freely from the base of the stem, forming large clusters, sometimes of almost the same size as the original stem.
    • The leaves are only up to approximately 50cm in length, with narrower leaflets, although longer leaves can be seen in some specimens.
    • The female cones are only up to 30cm long and up to 15cm in diameter.
    • The male cones, before elongation, and only approximately 20cm long and 8cm in diameter.

The seeds are only approximately 2cm long and 1,5cm in diameter.

Although smaller in these respects, the dwarf plants are similar to the typical form in all other respects. There are no distinct differences in cone or leaf characters. The dwarf nature seems to be persistent in cultivation.

Female cones

Male cones

Leaf detail

Distribution & Habitat


E. horridus occurs in the Eastern Cape Province, in the districts of Port Elizabeth and Uitenhage. Its habitat varies from Karroo scrub, including the dense Addo and Uitenhage bush, to sourveld near Port Elizabeth and from deep, fertile soil to infertile, rocky ridges. The vast majority of plants occur in the drier but more fertile areas where they grow amongst plants such as the indigenous spekboom (Portulacaria), noors (Euphorbia) and the alien prickly-pear. Rainfall varies from 250mm to 600mm per year and is fairly evenly distributed throughout the year. The climate is temperate and frost is unusual. Summer temperatures may be as high as 40°C or more.
Cultivation & Propagation


E. horridus grows well in the garden and once established, forms new leaves and cones regularly. It responds well to deep, fertile soil with sufficient organic material in the form of compost. The soil must be well-drained, however, and plants should be grown in full sun to preserve the blue colour of the leaves. E. horridus is very attractive amongst succulent plants, for example in a rockery, or may be used on its own as an accent plant or with low green shrubs to provide contrast. E. horridus is easily pollinated by hand and is easy to cultivate from seed. Seedlings do not grow fast, however, and it may take a few years before they can be planted in the garden. E. horridus can also be propagated by removing suckers from the parent plant.

 

Notes


Encephalartos horridus is a very distinctive South African cycad which has been known to botanists for almost 200 years. Its very characteristic leaves always make an impression on people who see it for the first time, as is evident from its name. It is not known who discovered E. horridus, botanically speaking, or when it happened but by 1801 at least one plant was growing in Vienna and in this year it was described, illustrated and named by Jacquin, who called it Zamia horrida. In 1834, when he introduced the genus name, Encephalartos, Lehmann changed the name to Encephalartos horridus. This species name is unique amongst South African cycads in that it is the only one with a negative connotation. Charles Joseph Chamberlain, who saw plants in habitat at Despatch during a visit in 1912, wrote: “It’s terrible leaves give it a clear title to its name” and concluded that “Encephalartos horridus is well named”.

E. horridus is most closely related to E. trispinosus, a very variable species which was separated from E. horridus in 1965. Before that it was known as E. horridus var. trispinosa. Some forms of E. trispinosus are the only other cycads which could be confused with E. horridus. With this exception, it is readily distinguished from other species, even in the absence of cones. The following differences occur between E. horridus and E. trispinosus:

  • E. horridus occurs only in the Port Elizabeth and Uitenhage districts and its distribution area does not overlap with that of E. trispinosus which occurs further east in the Bushmens and Fish River Valleys.
  • The median leaflets of E. horridus are wider and the twisting of the lobes on the lower surface of the leaflets is much more regular and uniform than in E. trispinosus, where the lobing is irregular, especially in the lower part of the leaf, where the leaflets are frequently entire. The leaflets of E. trispinosus are only distinctly lobed in the top part of the leaf.
  • The colour of young leaves of E. horridus is an intense silvery blue, whereas the leaves af E. trispinosus are less blue and green in some forms.
  • The cones of E. horridus are brownish-red in colour while those of E. trispinosus are yellow, greenish-yellow, or bluish-green.
  • The female cone scales of E. horridus are relatively smooth, with some ridges, while those of E. trispinosus are much wrinkled and pimpled.

In the Uitenhage district E. horridus grows together with E. longifolius and many hybrids have been found. Features of both parents as well as intermediate characteristics occur in these hybrids. Leaflets range from entire to deeply lobed. In most cases the green colour of E. longifolius predominates, while cone colour tends to be closer to that of E. horridus. The colour of young leaves of E. horridus is an intense silvery blue whereas the leaves of E. trispinosus are less blue and may be green in some forms. The cones of E.horridus are brownish-red in colour while those of E. trispinosus are yellow, greenish-yellow or blue-green. There has been also been unconfirmed reports of hybrids between E. horridus and E. lehmannii in the Uitenhage district.

E. horridus must have been very abundant untill fairly recently. Not many years ago it was still possible to see plants along the roads around Uitenhage. The numerous specimens in gardens in Uitenhage, Despatch and Port Elizabeth, and the fact that it is very well represented in collections in the rest of South Africa and overseas, indicate clearly that its days of abundance in nature are past. Only a few colonies are protected in the Springs Nature Reserve near Uitenhage. Although E. horridus has been declared an endangered species and may not be removed from its natural habitat without a permit, very few viable seeds seem to survive in nature. Almost all the seed appear to be infested with the curculionid weevil. The status of reproduction of E. horridus in nature therefore seems uncertain.