- Osyris compressa
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Osyris compressa 
Scientific classification Kingdom: Plantae (unranked): Angiosperms (unranked): Eudicots (unranked): Core eudicots Order: Santalales Family: Santalaceae Genus: Osyris Species: O. compressa Binomial name Osyris compressa
(P.J.Bergius) A.DCOsyris compressa (Cape Sumach or Pruimbos) is a facultatively hemiparasitic, [1] mainly South African plant of the Sandalwood family, Santalaceae. Until recently the favoured binomial name was Colpoon compressum, but the genus Colpoon was included in Osyris on the basis of comparative DNA studies.[2]
Contents
Distribution and Description
Osyris compressa is a shrub or small tree of up to 5 metres tall, though a more typical size for a plant growing in the open would be 2 or 3 metres. The leaves are opposite, decussate, blue-green with a greyish bloom, elliptical, smooth, stiff, typically about 20-50mm long, with thickened, entire margins. The inflorescence is a terminal panicle, bearing small, slightly fragrant, bisexual flowers. The flowers are creamy-green and unspectacular, but they appear through much of the year, attracting pollinating insects of various types. The ovary has 4 ovules, but the fruit is a single-seeded drupe, a prolate spheroid in shape. In size it is about 15 mm to 25 mm long and perhaps 10 mm to 15 mm across. The drupe is fleshy with a smooth skin crowned with the perianth lobes in a ring around its tip. Usually by the time the fruit is ripe, a circular groove is all that remains of the perianth. The fruit are colourful, progressing first from greenish blue to bright red, and then to glossy purple or black as they ripen; they mature at different rates, so the successive colours can be quite showy in combination.[3][4]
The species is mainly South African, occurring from the coastal fynbos in the region of the Cape Peninsula in the west, along the south coast and up into tropical East Africa.[4]
Reproduction and ecology
Osyris compressa is a tough and adaptable plant. It can withstand frost, heat and winds. It grows fast and survives in poor sandy soils, even in coastal dunes, where it may play a significant role as a windbreak and in binding sand. Being monoecious, and with bisexual flowers, and both cross-pollinating and self-fertile, the species produces fertile seeds prolifically. It begins to bear fruit when quite young, and it seeds plentifully practically throughout the year. The fruit attracts a range of birds and mammals that spread the seed effectively.
Osyris compressa, like many members of the family Santalaceae, exploit a facultative hemiparasitic ecological strategy to supplement their nutrient supplies, especially in dry conditions or poor soils. Their roots form haustoria that tap into the roots of nearby plants and extract their sap. Although Osyris compressa plants can grow without a host, this habit helps them to flourish in relatively poor coastal sands, and they need hosts if they are to grow at their best.[1] In this respect Osyris compressa resembles some other hemiparasites in related families such as Nuytsia floribunda in the Loranthaceae.
Being itself parasitic does not protect Osyris compressa from other parasites; several species of mistletoe in the genus Viscum (currently recognised as members of the same family as Osyris, namely Santalaceae) often parasitise its branches. Also, given that Osyris compressa is itself a root parasite, it is interesting to note that it in turn may be host to another root parasite in the same family, namely Thesidium fragile and possibly related species. It is not clear which, if either, of these rival root parasites benefits from the other when their roots meet.
Being a densely-leaved shrub with plentiful, if inconspicuous, flowers and edible fruit, Osyris compressa is of importance as a shelter and food plant for many animals. Of these probably the best-known is the butterfly Mylothris agathina, a member of the family Pieridae. Its common name is "Eastern Dotted Border" or "Common Dotted Border". Osyris compressa is not the only food plant for Mylothris agathina, but probably the most important in some regions.
Cultivation of Osyris compressa
This plant is popular in coastal gardens as an ornamental. It grows in coastal dunes and because of its vigorous and compact growth habit, it can be shaped into a dense hedge. It also produces attractive multi-coloured berries throughout the year that are ornamental in themselves and attract frugivorous birds.
Osyris compressa has been grown in programs to stabilize coastal dunes.
The leaves and bark used to be valued for tanning. The wood is high-quality and fine-grained, but the plant seldom produces trunks or limbs large enough for most uses. Although there does not seem to be much active cultivation of the plant, it seems to be of interest as a source of incense and essential oil in much the same way as sandalwood.[5]
The flesh of the berries is edible and formed part of the diet of the local Khoikhoi, both fresh and preserved as the dried pulp. It shows little promise as a popular fruit for westerners however, having a "tingly sour taste", according to some reports.[1] Others however describe it as "plum-like", and the Afrikaans name "pruimbos" means "plum bush".
An extract from the boiled bark has been used to flavour tea.
Osyris compressa can be propagated by seed.[6]
References and external links
- ^ a b c Visser, Johann (1981). South African Parasitic Flowering Plants. Cape Town: Juta. ISBN 0702112283.
- ^ Nickrent, D. L., and V. Malécot. 2001. A molecular phylogeny of Santalales. Pages 69-74 in A. Fer, P. Thalouarn, D. M. Joel, L. J. Musselman, C. Parker, and J. A. C. Verkleij, eds. Proceedings of the 7th. International Parasitic Weed Symposium. Faculté des Sciences, Université de Nantes, Nantes, France
- ^ Dyer, R. Allen, “The Genera of Southern African Flowering Plants”. ISBN 0 621 02854 1, 1975
- ^ a b Manning, John (2008). Field Guide to Fynbos. Cape Town: Struik Publishers. ISBN 9781770072657.
- ^ Watt, John Mitchell; Breyer-Brandwijk, Maria Gerdina: The Medicinal and Poisonous Plants of Southern and Eastern Africa 2nd ed Pub. E & S Livingstone 1962
- ^ http://www.plantzafrica.com/plantnop/osyriscomp.htm
- [Orwa C, A Mutua, Kindt R , Jamnadass R, S Anthony. 2009 Agroforestree Database:a tree reference and selection guide version 4.0 (http://www.worldagroforestry.org/sites/treedbs/treedatabases.asp)]
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