| Leucadendron | |
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| Leucadendron argenteum | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Proteales |
| Family: | Proteaceae |
| Subfamily: | Proteoideae |
| Tribe: | Leucadendreae |
| Subtribe: | Leucadendrinae |
| Genus: | Leucadendron R.Br. |
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| Natural range of the genus | |
| Synonyms[1] | |
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Leucadendron is a genus of about 80 species offlowering plants in the familyProteaceae,endemic to theCape Provinces andKwaZulu-Natal inSouth Africa, where they are a prominent part of thefynbosecoregion and vegetation type.[1]
Species in the genusLeucadendron are smalltrees orshrubs that are erect or creeping.[2] Most species are shrubs that grow up to 1 m (3 ft 3 in) tall, some to 2–3 m (6 ft 7 in – 9 ft 10 in). A few grow into moderate-sized trees up to 16 m (52 ft) tall. All areevergreen. Theleaves are largely elliptical, sometimes needle-like, spirally arranged, simple, entire, and usually green, often covered with a waxy bloom, and in the case of the Silvertree, with a distinct silvery tone produced by dense, straight, silky hairs. This inspired the generic nameLeucadendron, which literally means "white tree".
Theflowers are produced in denseinflorescences at the branch tips; plants aredioecious, with separate male and female plants.
The seed heads, orinfructescences, ofLeucadendron are woody cone-like structures. This gave rise to their generic common namecone-bush. The cones contain numerousseeds. The seed morphology is varied and reflects subgeneric groupings within the genus. A few such as the Silvertree,Leucadendron argenteum have a silky-haired parachute, enabling the large round nut to be dispersed by wind. A few are rodent dispersed, cached by rats, and a few haveelaiosomes and are dispersed by ants. About half the species store the seeds in fire-proof cones and release them only after a fire has killed the plant or at least the branch bearing the cone. Many such species hardly recruit naturally except after fires.
Leucadendron plants are conventionally propagated through seedlings as well as cuttings. The seeds reach maturity over a duration of a year. This time of germination and emergence depends on the species. When using cuttings as propagating material, the season as well as the type of material used can affect the success rate of the cultivation. Cuttings are preferred as propagating material because it provides uniform offspring, whereas seedlings producegenetic variability in the offspring. The genusLeucadendron is more prone togenetic variation than a genus that tends to self-fertilize, because of its cross-pollinating nature. In the natural habitat,Leucadendron grows exceptionally well, but in the case of cultivation the specific needs of the plant have to be readily available to allow optimal production of high qualitycut flowers and foliage. Steps for cultivation include soil evaluation, clearing, drainage, chemical correction, and the physical preparation should be critically considered five months prior to plantingLeucadendron.[3]
85 species are accepted.[1]
The drive behind the production of newLeucadendron cultivars is the production of a constant supply of new and improved quality products that are available initially from South Africa only.[4] The genusLeucadendron is popular amongst consumers due to its colourful bracts and long vase life.Leucadendron hybrids are produced through interspecific hybridization.[5] Crosses made within the same subsection are generally more viable in the hybridization ofLeucadendrons with the quantity of seed set relative to the taxonomic relatedness of the species. Intersectional hybridization produces hybrids that show a unique set of characteristics which are favoured by consumers. One example of a hybrid produced by twoLeucadendrongenera is the cultivar 'Rosette', a hybrid betweenL. laureolum andL. elimense. This interspecific hybrid is, however, completely sterile due toautopolyploidy and thus has no use in further cultivation. The main aim of interspecific hybridization is to produce large quantities of progeny seed from the best interspecific hybrid parents.[4]
In theUK the cultivars 'Safari Sunset'[6] and 'Inca Gold'[7] have gained theRoyal Horticultural Society'sAward of Garden Merit.[8]
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