| Protea burchellii | |
|---|---|
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| Protea burchellii, Proteaceae, flowerhead;Caledon, South Africa. | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Proteales |
| Family: | Proteaceae |
| Genus: | Protea |
| Species: | P. burchellii |
| Binomial name | |
| Protea burchellii | |
| Synonyms[2][4] | |
| |
Protea burchellii, also known asBurchell's sugarbush,[2][5][6][7] is a floweringshrub in the genusProtea,[2][5][6] which isendemic to the southwesternCape Region ofSouth Africa.[2][4]
The shrub is known by thevernacular name ofblinksuikerbos in theAfrikaans language.[7]
Protea burchellii wasdescribed byOtto Stapf in theFlora Capensis in 1912.[3][8] Although Stapf was unaware of it at the time,[8] the species had in fact been described in other works over a century before him, but under the nameP. pulchella or some of itssynonyms.[2][4]
The speciesP. burchellii had first been described just before the turn of the 18th century under the nameP. pulchella byHenry Cranke Andrews in his magazineThe Botanists' Repository,[9] however this name wasillegitimate, because it had already been used a few years before in 1796 byHeinrich Schrader andJohann Christoph Wendland for a plant that was growing in theRoyal Gardens of Hanover in what is now Germany,[10][11] which inRobert Brown's 1810 workOn the Proteaceae of Jussieu was moved toPetrophile pulchella.[11]
Nonetheless, Andrews'Protea pulchella lived on.Richard Anthony Salisbury moved it toErodendrum pulchellum in the notorious 1809On the cultivation of the plants belonging to the natural order of Proteeae published under the name ofJoseph Knight,[12][citation needed] much laterOtto Kuntze moved it toScolymocephalus pulchellus in 1891,[13] although hisProtea reclassification was soon rejected.Edwin Percy Phillips described aP. pulchella var.undulata, also known as variety β, for a plant with leaves with undulating margins,[citation needed] and then Stapf described aP. subpulchella in 1925.[14]
Stapf designated a specimen collected by the English explorerWilliam John Burchell numbered 8332 as theholotype. It was collected somewhere betweenSir Lowry's Pass andJonkers Hoek, in the area ofStellenbosch, at the very end of March, 1815.[8][15] Burchell had in fact collected atype series, according to the South AfricanbotanistJohn Patrick Rourke, and thus in 1978 accordingly designated one of the two specimen sheets labelled as Burchell8332 housed at theKew Herbarium as thelectotype; this specific sheet had originally been part of Burchell's personalherbarium, and had been donated to Kew upon his death by his widow in 1865.[15]
Thespecific epithet commemorates the collector of thetype specimens, William Burchell.[7][8]
The plant takes the form of a spreading, evergreen, multi-branched shrub.[6][7] It grows one or two,[7] or up to three metres in height,[6] and three metres wide. It has been called "mid-sized" for aProtea.[7] The branches all arise from a single, central,[7] branched, subterranean stem.[8] These branches are erect-growing according to some sources,[6][7] or, according to the original description, grow just above the ground. The upper, younger part of the branches are clothed in fine hairs.[8]
The length of a generation in this species is estimated to be around 20 years.[2] It is quite fast-growing, and in cultivation the first flowers can appear after the plant is two years old.[7]
The leaves are glossy,[8] olive-green in colour, and are spotted with tiny black points. Their shape is linear to narrowly oblong,[7] or also described as linear to narrowlyoblanceolate, attenuated on the lower part, with an acute but callous end. They are 6–9 inches (15–23 cm) in length and2⁄3–1 inch (1.7–2.5 cm) broad. The leaves have prominent veins on both sides, with lateral nerves that run into a narrow, somewhat thickened band along the margin. The leaves are usuallyglabrous, but may have anindumentum of fine hairs at and around their bases.[8]
It blooms in the Winter,[5][7] specifically primarily from June to August in most of its native South Africa,[6][8] but sometimes into Spring on theCape Peninsula.[5] The flowers are clustered together in apseudanthium, a special type ofinflorescence, which is also called aflower head. In this species this structure will grow up to 10 centimetres (3.9 in) in length by 7 centimetres (2.8 in) in diameter,[7] although the original description gives a length of 2.5 inches (6.4 cm) and diameter of 1.5 inches (3.8 cm). It is almost round in shape, has a rounded base, and lacks apeduncle (i.e. it issessile).[8]
The flower head is surrounded by petal-like appendages called 'involucral bracts'.[7][8] The bracts are often pink, but forms with white-coloured bracts exist, as do red-[5] and yellow-coloured forms. The colour range has been described as "cream-coloured to deep carmine",[7] or "dark chestnut-brown" for the outer bracts in the original description (possibly based on dried herbarium material). The outer bracts are ovate in shape, with their ends obtuse (blunt) to somewhat obtuse, and when very young are covered in a layer of greyish, finelypubescent hairs, with the margins of the bracts being ciliate (i.e. fringed with a hairs like an eyelash), although this soon falls off and they become glabrous. The inner bracts are oblong and elongated in shape and their ends are obtuse; they are just a bit smaller in length than the actual flowers.[8]
The plant ismonoecious with both sexes in each flower.[6] Thepetals andsepals of the flowers are fused into a 1.25 inches (3.2 cm) longperianth-sheath. The last two thirds of this sheath is slender, but then it widens towards the base, this area having three inconspicuous keels and five veins. The outside of the sheath is covered in dense amounts of dark brown, pubescent hairs on the slender part, but the widened base isciliolate but otherwise glabrous. The sheath has a 12.7 mm long lip. This lip is shaggy-haired (i.e.villous), except for its back, which isglabrescent. The two outer of these teeth are much longer than the middle one: they are thread-like in shape, sharply pointed, and 3.2 mm long, whereas the middle one is much shorter and less conspicuous. All of thestamens are fertile. Theirfilaments are 0.53 mm long and widen towards their tops. Theanthers are linear and 4.2 mm long. The apical glands are 0.53 mm in length, oblong in shape and end in an obtuse point. Theovary is densely covered in reddish hairs and is subobovate-oblong in shape. Thestyle issubulate andterete, and arises from a narrowly compressed and obliquelylanceolate base. It is 3.7 mm long, covered in pubescent hairs from the top up until its middle section, strongly curved below its middle, and constricted where it joins with the ovary. Thestigma is subulate, with an obtuse end, and almost imperceptibly becomes the style.[8]
The fruit is anut.[7] The seed is stored in a capsule which is retained in the dried, fire-resistant inflorescence, which itself remains attached to the plant aftersenescence. When they are eventually released after fires stimulate the capsules to open, the seeds are dispersed by means of the wind.[2][6][7]
Protea burchellii isendemic to the southern and southwesternCape Region of South Africa,[2][4] where it is only found in theWestern Cape province.[2][5] The range extends from theHottentots Holland Mountains to theOlifants River Mountains, and on the lowland flatlands on theCape Peninsula (historically) to the plains of theHopefield Flats. Isolated populations occur on theWitzenbergvlakte,Piketberg, and the upper part of theBreede River Valley.[2][6][7] It grows around thePaarl Rock and near the town ofMamre.[5]
The periodicwildfires which occur in its habitat will destroy the adult plants, but the seeds can survive such an event safely stored in the old flower heads.Pollination occurs through the action of birds.[2][6][7]
The plant grows in a variety ofhabitats but prefers to grow in more fertile soils,[2][6][7] fully exposed to sun on lower mountain slopes.[7] It has been found growing infynbos,renosterveld, coastal vegetation and the vegetation found on the more fertileshale bands. It often grows in shale, but it is found in a variety of soil types as well:alluvium, sand andsilcrete; as well as substrates derived fromgranite.[2] It occurs at altitudes of 100 to 850 metres.[2][6][7]
Protea burchellii and its hybrids are popular crops in thecut flower industry.[7]
This species is quitewinter hardy for use in South African gardens. Many hybrid varieties are commercially available in South Africa. It can be used in therock garden, as a specimen plant, or, due to its average height, as a shrub in the mid-layer of the border. It is best grown in a sandy, well-drained, fynbos soil.[7]
Propagation is easiest done by sowing the seeds, but it has also been achieved viacuttings. Seeds should be sown shallowly in May in South Africa (late autumn) in a well-drained substrate treated with afungicide.Germination requires warm day and cold night temperatures. Germination is irregular, with some seeds starting to grow a year after sowing. Seedlings are easily killed by overwatering. Cuttings can be taken from the tips of shoots from December to March in South Africa. These should be treated with arooting hormone, planted in a very well-drained substrate, and kept moist, but not wet. Roots should appear after some five weeks.[7]
The pathogenic, fungi-likePhytophthora is an important disease of the roots in cultivated plants. Infected plants become wilted and dry, eventually yellowing and then dying. The best one can do in such situations is to pull up the plant and burn it, apply fungicide to the soil where the plant stood, and no longer replantProteaceae in that area.[7]
In 1998 and in 2008Protea burchellii was considered locally common and not threatened, but by this time the species was already considered extinct on theCape Peninsula.[6][7] Nonetheless, it has been photographed blooming on theLion's Head on the Cape.[5]
The species was classified as "vulnerable" on the Redlist of South African Plants by theSouth African National Biodiversity Institute (SANBI) in 2008; this was upheld again in 2009. They believe the total population numbers are decreasing.[2]
It grows in areas generally unsuitable for normal cultivation, and mosthabitat loss was thought to be fairly recent in 2008. Nonetheless, SANBI estimated that the 'historical' population had been reduced at least 30% based on a habitat loss of some 40%, primarily to agricultural development. This was especially caused by the recent success of the vineyards and olive orchards. SANBI estimated that with the continuing viability of these farms a further reduction of the population by 30% is likely by the year 2028. Other threats identified by SANBI areover-harvesting,pollution,invasive plants, natural disasters and changes in native species dynamics.[2]
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