Gymnosporia harveyana

Loes.

Family:
Celastraceae
Common names:
black forest spikethorn (Eng.); swartbospendoring (Afr.)

Fruit and leaves

This is an evergreen, dense, spiny shrub or small tree, with lovely shiny foliage and small white-and-red fruits. It is suitable for small gardens as a background planting or can be pruned into a creative shape for special accent in a garden.

Description
Gymnosporia harveyana is a densely leafy, evergreen shrub or small tree that is usually about 2 m high, but it can grow up to 6 m if given enough space and filtered sunlight.

Thread -like stipules and the base of the leavesIt bears slender, straight spines up to 70 mm long in the axils of the leaves or on the brachyblasts (short shoots). This spikethorn can be easily identified by its conspicuous, thread-like stipules (leaf-like structure at the base of the leaf), up to 2 mm long. The young branchlets are angular. The hairless leaves have a distinct petiole (leaf stalk), are thinly leathery, shiny bright green above and paler below and are clustered together on older twigs or alternate on younger ones. The leaf blade is ovate or elliptic to rounded, 10-40 x 6-25 mm, with a sharp apex and sharp to rounded base; the margin is irregularly toothed and the teeth are very sharp and incurved; the venation is more prominent below than above and the midrib is raised on both sides.

The very small, white flowers are borne in small bunches. One finds separate male and female trees. Male flowers have five sepals (units of the calyx), five petals, five stamens and a short nonfunctional ovary.Female flowers have five sepals, five petals, five very short nonfunctional stamens, shorter than those of the male flowers, and a functional ovary with a 3-branched style at the top.

Open capsule showing seed.The fruits are white on one side and red on the other, round, semi-fleshy and pendulous on long, slender stalks. When dry, the capsules split open in three parts and reveal the seeds, which are almost completely enclosed by an orange aril (an outer covering).

There are flowers or fruits on the trees almost all year round and the species is not threatened or vulnerable in the wild.

Distribution and Habitat
Gymnosporia harveyana is fairly widespread in the subtropical, eastern parts of southern Africa in forest margins or as an understorey shrub or small tree in inland forests of the Soutpansberg and Drakensberg escarpments in the Limpopo Province, Mpumalanga, Swaziland and KwaZulu-Natal. Its distribution extends further southwards into the coastal forests of KwaZulu-Natal and the Eastern Cape as far as Uitenhage. Further northwards it occurs on the Vumba and Inyangani Mountains in Zimbabwe and Chimanimani Mountains on both sides of Zimbabwe and Mozambique, on the Nyika Plateau in Malawi and as far north as Njombe in Tanzania. In its forest habitat in the wild it is protected from frost and is adapted to warm to hot and humid or moist conditions, with moderate rainfall all through the year, especially in summer.

Derivation of name and historical aspects
Gymnosporia: gymno is the Greek for naked and sporia means seed. The name alludes to the seeds: although they are enclosed by the aril or outer covering, they lie open or naked in the capsule when it splits open. The name harveyana honours the renowned botanist William Henry Harvey (1811-1866), who was born in Ireland, the youngest of eleven children. He came to the Cape when he was 23 years old and stayed about four years before he returned to Ireland where he was the Keeper of the Herbarium of Trinity College, Dublin. In later years he was associated with the University of Dublin and, with Dr O.W. Sonder of Hamburg, he wrote three volumes of Flora capensis from 1860-1865.

G. harveyana is one of ± 35 species of Gymnosporia in southern Africa and 108 in the world; the genus belongs to the family Celastraceae. Gymnosporia is an Old World genus of trees, shrubs and dwarf shrubs, comprising about 108 members occurring in Africa, Madagascar and adjacent islands, southern Spain, the near Middle East, Pakistan, India, Sri Lanka, Thailand, Vietnam, S China, Taiwan, Ryukyu Islands, Malesia, Queensland (Australia) and the Polynesian Islands. G. harveyana was previously considered to be the same as G. mossambicensis or Maytenus mossambicensis. Today they are recognized as two distinct species.

G. mossambicensis also occurs in South Africa, but only in the most northern part of the Limpopo Province and low-lying areas in Mozambique. It is a multistemmed shrub in mixed woodland, without the conspicuous stipules, but also with white flowers, not tiny and red as in G. rubra, a small shrub that also occurs in forest margins. In the past, G. mossambicensis was known by the common name, black forest spikethorn, but this name is now applied to G. harveyana. A closely related species with which it is often confused, G. nemorosa, has conspicuous white lenticels on the twigs and is known as the white forest spikethorn.

Other noteworthy members of the family are the spindle trees (Euonymus species) which are cultivated as ornamentals for their attractive autumn colours and brightly coloured fruits.

Ecology
When the capsules dry out on the trees or are picked and left to dry out for a few days, it is interesting to notice that the valves inside are pink, becoming purple, in contrast with the orange arils. This attractive colour system of dark purple and orange invites birds and they disperse the seeds. Flowers and/or fruits can be found on trees all through the year.

Like other indigenous trees, G. harveyana grows slowly to moderately fast, but should last for many years once it is established. It usually forms stands if given the opportunity. The small, inconspicuous flowers of the spikethorns are usually produced in profusion, especially in the case of G. buxifolia and have a sweet or most unpleasant smell which attracts especially flies as pollinators, but ants, bees and certain beetles also visit the flowers.

Uses and cultural aspects
The roots and leaves of other species of Gymnosporia such as G. senegalensis, G. buxifolia and G. putterlickioides are used medicinally, but G. harveyana has been not been recorded to have special medicinal or cultural value.

Growing Gymnosporia harveyana

In the wild it grows in full shade in forest, so it will be best placed in a shady spot in the garden, its shiny leaves providing a lovely background. It can be propagated from seed. Like G. bachmannii, a closely related species (Joffe 2003), the seed must be sown in well-drained, fertile soil that contains plenty of compost and it should be watered well during the summer period. Young plants require protection from frost. The shrub can be pruned into a creative shape. No pests are known to attack this plant.

References and further reading

  • Gunn, M. & Codd, L.E. 1981. Botanical exploration of southern Africa. Balkema, Cape Town.
  • Joffe, P. 2003. Creative gardening with indigenous plants. a South African guide, edn 1, impression 2. Briza Publications, Pretoria.
  • Jordaan, M. 2003. A taxonomic revision of the Gymnosporia mossambicensis group (Celastraceae: Celastroideae). Kew Bulletin 58: 833-866.

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    M. Jordaan
    National Herbarium, Pretoria
    June 2004

     

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