Plant taxonomy or classification is the science of naming organisms and placing them in a hierarchical structure, each level being given a name (e.g., kingdom, division (phylum), class, order, family, genus, species).
The family Proteaceae comprises of 83 genera with about 1,660 known species. Genera includes among others Protea, Leucospermum, Leucadendron, Mimetes, Serruria, Aulax, Banksia, Embothrium, Grevillea, Hakea and Macadamia. Species such including Telopea speciosissima), Protea cynaroides, and various species of Banksia, Grevillea, and Leucadendron are sought-after cut flowers, while the nuts of Macadamia integrifolia are widely grown commercially and consumed.
DISTRIBUTION OF PROTEACEAE
Proteaceae are mainly a Southern Hemisphere family, with its main centres of diversity in Australia and South Africa. However members of the Protea family also occur in Central Africa, South and Central America, India, eastern and south eastern Asia, and Oceania. Two species are known from New Zealand, although fossil pollen evidence suggests there were more previously.
Genera endemic to Australia include Banksia and Hakea. Telopea species which resembles the South African pincushion can be found growing in Australia and Tasmania while species from the Grevillea genus occurs in Australia and New Guinea and the Indonesian Islands. Embothrium species are native to South America. A single species is known to occur in Madagascar namely, Malagasia alticola.
The fossil record of some areas, such as New Zealand and Tasmania, show a greater biodiversity for Proteaceae than currently exists, which supports the fact that the distribution of many taxa has changed drastically with the passage of time and that the family has suffered a general decline, including high levels of extinction.
Protea odorata / Swartland Sugarbush
Protea odorata is a small, sparsely branched, evergreen, fynbos shrub, that grows about 0.7–1.2 m high. It has a single stem, hairless and brown with age. The leaves are hairless and have a bent spine at the tip that might slightly hurt the hand when touched. The spines are pinkish to reddish when leaves are young and turn black as they age. Protea odorata flowers from late summer to mid-winter (February to June), peaking in abundance in autumn (from March to April). The fruits are serotinous (retained within the seed head on the plant for years) and take about 7 months to ripen.
Protea odorata is endemic to Malmesbury Flats, from Klapmuts to Riverlands. It grows in slightly saline, klipheuwel gravels, mixed with sands in flatlands. Protea odorata almost became extinct (Rebelo 2001). It used to occur in Atlantis and Cape Flats Sand Fynbos, but is extinct in these areas. It survives in a transitional patch of Alluvium Fynbos/Swartland Shale Renosterveld.
Protea odorata flowers have a slight sweet fragrance and are pollinated by wasps. When the proteas die or are killed by fire, the serotinous (retained) fruits open and the seeds fall out and become available food for rodents and birds until the seeds germinate after the autumn and winter rain. The seeds of Protea odorata have a softer coat with hairs that hold the seed into the damp soil after they have been dispersed by wind.
Protea odorata is assessed as Critically Endangered (CR). This is caused by too frequent fire, agricultural expansion, invasive alien plants, overgrazing and road construction. The bulk of the populations are extinct, and only a single marginal population of about 5 plants still survive.
Leucadendron chamelaea / Witzenberg conebushConservation Status: Critically Endangered
Leucadendron means ‘white tree’. The species name chamelaea, is derived from the Greek word chamae, which means ‘low, or on the ground’, referring to a creeping habit.
Leucadendron chamelaea is one of the iconic species of the Upper Breede River Valley. This species once occurred commonly in this area, but through the intensification of agricultural practices, it has suffered severe population reduction and is now on the brink of extinction in the wild.
Leucadendron chamelaea is Critically Endangered (CR). A past population reduction of at least 60% is estimated, based on 55% habitat loss because of agriculture and the local extinction of 52% of subpopulations known through herbarium records. Remaining subpopulations are fragmented and largely confined to road verges and adjacent areas. This species is also an indicator of special habitat, and wherever there are populations of this species, numerous other threatened plants at these sites.
This species grows in sandy flats and has rather large flowerheads. It is a single-stemmed species, so is killed by fire and regenerates from seeds. The seeds are held in the cones, but the cones are not tightly closed, so once the seeds are ripe, they can fall to ground out of the cones if they are knocked or blown by a strong wind. Plants flower in spring (September to October), are strongly scented and are pollinated by insects. Seeds ripen within two months.
Leucadendron salignum / Common sunshine conebush
Leucadendrons are dioecious, i.e. separate male and female plants. This is unusual in the protea family. Its long flowering season (May – Dec), coupled with colourful leaves and bracts surrounding the flowers, make this species an attractive garden plant.
There are a range of plants in cultivation, which differ markedly from the usual parent species, most often in growth form, leaf- and bract colour and flowering time. They may be either selections, known as ‘cultivars’ or hybrids, i.e. ‘crosses’ between species. Many hybrids and cultivars have been produced in South Africa, New Zealand, Australia and other countries growing Proteaceae
It is common from Port Elizabeth in the east, to north of Ceres in the west. It occurs on a wide range of soil types, from sea level to an altitude of 2000 m and is quite variable in leaf size as well as leaf- and bract colour.
Leucadendron strobilinum / Peninsula conebush
Conservation Status: Near Threatened
The word Leucadendron is derived from the Greek word leucos, meaning white, and dendron, meaning a tree, referring to the silver tree, Leucadendron argenteum. Strobilinum comes from the Greek strobilos (cone) and is a reference to the resemblance of this plant’s cones to pine cones.
Leucadendron strobilinum is a large, single-stemmed shrub that branches from the base. It grows up to 2.6 m tall. The leaves are dark green and oval. The leaf tips are red and recurved with a fine point. The fruiting cones are ovoid and hairless and contain flat, winged seeds. It flowers from September-October. It occurs on the Cape Peninsula, and the distribution ranges from Table Mountain to Kommetjie. It grows on damp, rocky slopes.
The plants regenerate from seed. The seeds are stored in the cones on female plants from which they are released after fire. The seeds are dispersed by wind. Leucadendron strobilinum has plants of separate sexes, the male and female flowers occur on separate plants. Flowers are pollinated by small beetles.