Colpoon compressum P.J.Bergius (=Osyris compressa (P.J.Bergius) A.DC)
Common names: Cape sumach, coast tannin bush (Eng.); wildepruim, wurgbessie, basbessie, kuslooibas, namtarri (Afr.); mtekaaza, umbalanythi (Xhosa); umbulanyathi (Zulu)
SA Tree No: 99
Colpoon compressum, is a very decorative and useful plant in cultivation as well as in its natural habitat. It is a hemi-parasitic plant, in other words a plant that is capable of producing its own food (by photosynthesis) as well as utilising nourishment from a suitable host plant by means of parasitism. This, together with some other interesting features, makes the Cape Sumach a highly successful species in the Cape Floristic Region and in other vegetation types.
Colpoon compressum is classified as a shrub although it can attain the size of a small bushy tree of 1-5 m in height. It is a partial parasite on the roots of plants. The Cape sumach has a smooth greyish bark and the leaves are opposite, stiff, erect and crowded up the stem.The elliptical leaves, which are tough and leathery, are 10-50 x 10-27 mm, and blue-green with a grey bloom.
The flowers are small, about 2 mm across, yellowish green, slightly scented, inconspicuous, and are borne in small terminal heads or panicles. Flowers are either just male on one plant or hermaphroditic (can be male and female on the same plant). The flowers and fruits are produced erratically throughout the year, but mainly from April to December.
The fruits are highly decorative on the plant and are ellipsoid (elliptic in long section and circular in cross section), fleshy, about 15 x 10 mm, becoming bright, shiny red and then purplish black. Fruits don't ripen all at once which is why these plants can be very attractive for long periods throughout the year.
Least Concern (LC). Colpoon compressum is a very tough and well-established plant in its native habitat. The plants are relatively short-lived but highly developed as can be noticed by the abundance of fruits each plant produces throughout the year, enabling it to secure maximum offspring. Its semi-parasitic lifestyle also gives it an added advantage over other plants. Colpoon compressum is not threatened or in danger of becoming threatened.
Distribution and habitat
Colpoon compressum occurs on coastal dunes and inland slopes from Namaqualand and the Cedarberg in the Western Cape along the south and east coast to Kosi Bay in KwaZulu-Natal. Associated biomes include mountain and coastal fynbos as well as savanna habitats. Plants thrive in sandy conditions and are an important soil stabiliser in coastal dune systems. Colpoon grows in close proximity to other plants, such as species of Rhus, Coleonema, Maytenus, Leucadendron, Metalasia and Chrysanthemoides.
Derivation of name and historical aspects
The generic name is from the Greek kolpos, meaning 'breast' or 'womb, possibly referring to the shape of the berries. The specific epithet compressum means laterally flattened.
There has been some taxonomic confusion about the status of the genus Colpoon, and its South African relatives in the Santalaceae, Osyris and Rhoiacarpos. In 1961, a study by Stauffer recognised them as three distinct genera. Then in 1994, Hilliard placed Colpoon in synonymy within Osyris, seeing no essential difference in their floral structure, and this species became Osyris compressa. Now, recent molecular phylogenetic studies have shown that these three genera are indeed distinct, and Colpoon has been re-instated.
The genus Colpoon contains two species: C. compressum and C. speciosum.
This species is similar to an inland species, namely Osyris lanceolata (Transvaal Sumach), but the latter can easily be recognised by the alternate leaves and the axillary flowers.
Colpoon compressum is designed for survival. Its blue-green, leathery leaves enable it to withstand heat and wind intensities normally associated with the coast. It is a fast grower and establishes itself rapidly through masses of seeds, which are produced for at least eight months of the year.
As it is hermaphroditic, the plant has a much greater chance of producing viable seeds faster and it ensures that cross-pollination takes place between separate plants which creates a stronger gene pool for the species.
The scented flowers attract insectiverous pollinators ranging from bees and butterflies to flies and ants. Colpoon compressum is also an important food plant for the larvae of the Common Dotted Border (Mylothris agathina ), a yellowish, medium-sized butterfly that occurs along the coast. The glossy green berries grow fast and become dark red to purple and then fall to the ground. Many different birds feast on these berries and in so doing ensure the effective spread of the plants.
As with the other member of the Santalaceae family, the Cape Sumach parasitises nearby plants by means of root attachments. The young plant may utilise water and important nutrients from the host plant, and may become less dependent as it matures; the plant is not entirely dependent on host plants and can survive on its own should the host plant die, until another suitable host is found. There are no known benefits to host plants once they have become parasitised.
The fresh leaves of Colpoon compressum were used to tan leather a light brown colour, while the bark was used to tan leather dark brown. A layer of crushed leaves or bark, depending on colour preference, was put into the bottom of a trough and the hide with hair removed was placed on top of the plant material. Successive layers of plant material and hides were made, and the wet mass was pressed flat with weights and left to tan for two weeks before removing and drying. A decoction of fresh leaves was used to tan cotton, fishing lines and nets to make them more durable in the days before nylon.
The wood is heavy and fine-grained but, because of the small size of the tree, it is suitable only for ornaments. The fruits are edible and were an important food for the early inhabitants of the Cape. The stone was removed and the fleshy part compressed and stored for lean times.
Growing Colpoon compressum
Colpoon compressum plants grow from seeds which fall to the ground. Seeds can be sown in situ (directly in the open garden), if there are other plants to serve as the hosts. It is not possible to grow plants from cuttings. Colpoon is not well established in cultivation and is best left to reproduce naturally. Plants do exceptionally well in coastal areas and are very tolerant of windy conditions. It is recommended as a seaside subject, and plants form very effective small windbreaks provided there are enough host plants. They also attract birds and insects to the garden and do well with the other more common Coastal Fynbos vegetation from the Asteraceae, Rutaceae, Proteaceae, and Anacardaceae families.
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- Stearn, W.T. 2003. Stearn's dictionary of plant names for the gardener .Cassel, UK.
- Van Rooyen, G. & Steyn, H. 1999. Cederberg Clanwilliam & Biedouw Valley South African wildflower guide 10. Botanical Society of South Africa, Cape Town.
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Kirstenbosch National Botanical Garden
Updated by Alice Notten, July 2018
Plant Type: Shrub, Tree
SA Distribution: Eastern Cape, KwaZulu-Natal, Western Cape
Soil type: Sandy, Clay, Loam
Flowering season: Sporadic/All year
PH: Acid, Alkaline, Neutral
Flower colour: Green, Cream
Aspect: Full Sun
Gardening skill: Average, Challenging
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