Protea

Etymology

The genus Protea was named in 1735 by Carl Linnaeus when he was examining male and female plants of a species now known as Leucadendron argenteum which are very different from each other; he misunderstood them to be two different species, and he compared those forms to the ability of Greek god Proteus who could change his form at will. Linnaeus's genus was formed by merging several genera previously published by Herman Boerhaave, although precisely which of Boerhaave's genera were included in Linnaeus's Protea varied with each of Linnaeus's publications.

Taxonomy

The family Proteaceae to which Protea species belong is an ancient one among angiosperms. Evidence from pollen fossils suggests Proteaceae ancestors grew in Gondwana, in the Upper Cretaceous, 75–80 million years ago. The Proteaceae are divided into two subfamilies: the Proteoideae, best represented in southern Africa, and the Grevilleoideae, concentrated in Australia and South America and the other smaller segments of Gondwana that are now part of eastern Asia. Africa shares only one genus with Madagascar, whereas South America and Australia share many common genera – this indicates they separated from Africa before they separated from each other.

Description

Proteas usually flower during spring. Protea flowers have large heads made of small florets packed on a woody receptacle, each floret is reddish or pinkish in color and measures between 28.4 and 53.8 millimeters. The carpel in the flower's center is cream colored. The ovary is protected by the receptacle, and thus is not seen when looking at the flower, but the anthers are present at the top of the flower, which can then easily transfer the pollen to the vectors.

Proteas are pollinated by birds, insects, and wind. All the florets open big enough for small and medium beetles to land and feed on their nectar before flying to other heads pollinating them in the process. Some protea flower species, like the king protea flower, are self-pollinating flowers. Other protea species, however, such as P. cordata, P. decurrens, and P. scabra are self-incompatible, and thus rely on cross-pollination for successive seed sets. Some Protea species exhibit both self-pollination and cross-pollination as a method of reproduction. Cross-pollination is preferred, though, as a method of reproduction because it provides genetic diversity in the population. When cultivating proteas, breeders use hand pollination as a controlled method to transfer pollen from one flower to another.

• Cover the inflorescence, which contain only closed flowers, with a plastic bag
• Once the first few flowers have opened, most have to be cut back to 10-20 flowers around the receptacle
• After 3 days, the pollen may be applied using a toothpick. The flower should then again be covered with a plastic bag and marked with a tag containing information regarding the seed, the parent, and the date of pollination. This step should be repeated until all the flowers are opened and pollinated.
• The seed head should be harvested at 9-12 months and dried at temperatures more or less at 40°C to remove the seeds from the receptacle
• The seeds can be germinated in autumn using hot water
• The seeds should then be placed in a sterilized potting medium for germination. --

Genetics

The common Proteaceae plants, e.g. Protea, Leucospermum, and Leucadendron are diploid organisms, thus they can freely hybridize with closely related species to form new cultivars. Unusually, not all the genera within the family Proteaceae can hybridize freely; for example, Leucadendron species cannot be crossed with Leucospermum species because of the difference in their haploid chromosome number (13 and 12, respectively). This genetic incompatibility results in pollinated flowers that yield either no fruit, or seedless fruit, as the resulting plant embryos, from the incompatible pollen and ovum, fail to develop.

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Botanical history

Proteas attracted the attention of botanists visiting the Cape of Good Hope in the 17th century. Many species were introduced to Europe in the 18th century, enjoying a unique popularity at the time amongst botanists.

Cultivation

Proteas are currently cultivated in over 20 countries. Cultivation is restricted to Mediterranean and subtropical climates. Three categories of traits have to be considered before developing a new cultivar. The yield or production capacity of the cultivar must be considered. The ease of handling and packaging of the cut stems and the last category is to consider the perceived market value of the cultivar. The cultivation of a *Protea *plant is time-consuming, so good planning when developing the cross combinations and goals are of great importance of the breeding programme.

Classification

Within the huge family Proteaceae, they are a member of the subfamily Proteoideae, which has Southern African and Australian members.

Species

Main article: List of Protea species

(listed by section: a 'section' has a name in two parts, consisting of the genus name and an epithet).

• Protea sect. Leiocephalae
  • Protea afra (common protea)
  • Protea dracomontana (Drakensberg sugarbush)
  • Protea glabra (Clanwilliam sugarbush)
  • Protea inopina (large-nut sugarbush)
  • Protea nitida (wagon tree)
  • Protea nubigena (cloud sugarbush)
  • Protea parvula (dainty sugarbush)
  • Protea petiolaris (sickle-leaf sugarbush)
  • Protea rupicola (krantz sugarbush)
  • Protea simplex (dwarf grassland sugarbush)
• Protea sect. Paludosae
  • Protea enervis (Chimanimani sugarbush)

• Protea sect. Patentiflorae
  • Protea angolensis (woodland sugarbush)
  • Protea comptonii (saddleback sugarbush)
  • Protea curvata (Barberton sugarbush)
  • Protea laetans (Blyde sugarbush)
  • Protea madiensis (tall woodland sugarbush)
  • Protea rubropilosa (Transvaal sugarbush)
  • Protea rupestris (rocket sugarbush)
• Protea sect. Lasiocephalae
  • Protea gaguedi (African sugarbush)
  • Protea welwitschii (dwarf savanna sugarbush)
• Protea sect. Cristatae
  • Protea asymmetrica (Inyanga sugarbush)
  • Protea wentzeliana (Wentzel's sugarbush)
• Protea sect. Protea
  • Protea cynaroides (king protea)
• Protea sect. Paracynaroides
  • Protea cryophila (snow protea)
  • Protea pruinosa (frosted sugarbush)
  • Protea scabriuscula (hoary sugarbush)
  • Protea scolopendriifolia (Hart's tongue-fern sugarbush)
• Protea sect. Ligulatae
  • Protea burchellii (Burchell's sugarbush)
  • Protea compacta (Bot River sugarbush)
  • Protea eximia (broad-leaf sugarbush)
  • Protea longifolia (long-leaf sugarbush)
  • Protea obtusifolia (limestone sugarbush)
  • Protea pudens (bashful sugarbush)
  • Protea roupelliae (silver sugarbush)
  • Protea susannae (stink-leaf sugarbush)
• Protea sect. Melliferae
  • Protea aristata (Ladysmith sugarbush)
  • Protea lanceolata (Lance-leaf sugarbush)
  • Protea repens (common sugarbush, Honey flower, Sugarbush)
• Protea sect. Speciosae
  • Protea coronata (green sugarbush)
  • Protea grandiceps (red sugarbush)
  • Protea holosericea (saw-edge sugarbush)
  • Protea laurifolia (gray-leaf sugarbush)
  • Protea lepidocarpodendron (black-beard sugarbush)
  • Protea lorifolia (strap-leaf sugarbush)
  • Protea magnifica (queen sugarbush)
  • Protea neriifolia (oleander-leaf protea, narrow-leaf sugarbush)
  • Protea speciosa (brown-beard sugarbush)
  • Protea stokoei (pink sugarbush)
• Protea sect. Exsertae
  • Protea aurea (common shuttlecock sugarbush)
  • Protea lacticolor (Hottentot sugarbush)
  • Protea mundii (forest sugarbush)
  • Protea punctata (water sugarbush)
  • Protea subvestita (waterlily sugarbush)
  • Protea venusta (creeping beauty)
• Protea sect. Microgeantae
  • Protea acaulos (common ground sugarbush)
  • Protea convexa (large-leaf sugarbush)
  • Protea laevis (smooth-leaf sugarbush)
  • Protea revoluta (rolled-leaf sugarbush)
  • Protea angustata (Kleinmond sugarbush)
• Protea sect. Crinitae
  • Protea foliosa (leafy sugarbush)
  • Protea intonsa (tufted sugarbush)
  • Protea montana (Swartberg sugarbush)
  • Protea tenax (tenacious sugarbush)
  • Protea vogtsiae (Kouga sugarbush)
• Protea sect. Pinifolia
  • Protea acuminata (blackrim sugarbush)
  • Protea canaliculata (groove-leaf sugarbush)
  • Protea nana (mountain-rose sugarbush)
  • Protea pityphylla (Ceres sugarbush)
  • Protea scolymocephala (thistle sugarbush)
  • Protea witzenbergiana (swan sugarbush)
• Protea sect. Craterifolia
  • Protea effusa (Marloth's sugarbush)
  • Protea namaquana (Kamiesberg sugarbush)
  • Protea pendula (arid sugarbush)
  • Protea recondita (hidden sugarbush)
  • Protea sulphurea (sulphur sugarbush)
• Protea sect. Obvallatae
  • Protea caespitosa (bishop sugarbush)
• Protea sect. Subacaules
  • Protea aspera (rough-leaf sugarbush)
  • Protea denticulata (tooth-leaf sugarbush)
  • Protea lorea (thong-leaf sugarbush)
  • Protea piscina (Visgat sugarbush)
  • Protea restionifolia (reed-leaf sugarbush)
  • Protea scabra (sandpaper-leaf sugarbush)
  • Protea scorzonerifolia (channel-leaf sugarbush)

A hybrid is defined as an offspring between two plants of different species or varieties. Inter- or intraspecific hybridization is used in the cultivation of flowers to improve the qualities including bract colour, flowering time and disease resistance. Intraspecific hybridization refers to a hybrid between different genotypes of the same species whereas interspecific hybridization refers to the progeny between two different species of the same genus. Hybrid flowers are more adaptable to different environments than the pure species, this is why the cultivation of hybrids are preferred. Hybridization of protea flowers is common amongst the genus Leucadendron to produce unique set of characteristics to meet the market requirements and thus increases market exports and changes the market trend. It is often difficult to identify hybrids from a population based on morphological features, because of the resemblance the species show towards the parent plants. For this reason molecular markers such as RAPD, AFLP, or microsatellite markers and PCR-RFLP are useful in identifying hybrid plants. Another common hybrid is the Protea emixia which is cultivated to flower during the spring and summer months and thus provides cut flowers for export to the Northern Hemisphere. The hybridization of proteas is usually started by covering the inflorescence of the female plant with a plastic bag to exclude external sources of pollination. After two days the unopened flowers are removed from the inflorescence leaving approximately 40 to 60 opened flowers. The pollen is then hand applied using a brush and the inflorescence is covered again.--

References

References

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