Restionaceae

Restionaceae
Temporal range: Late Cretaceous-Recent, 66–0Ma
Elegia capensis
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Monocots
(unranked): Commelinids
Order: Poales
Family: Restionaceae
R.Br.[1]

The Restionaceae, also called restiads and restios, are a family of perennial, evergreen rush-like flowering plants native to the Southern Hemisphere; they vary from 10 cm to 3 m in height. Based on evidence from fossil pollens, the Restionaceae likely originated more than 65 million years ago during the Late Cretaceous period, when the southern continents were still part of Gondwana.[2]

Description

The family consists of tufted or rhizomatous, herbaceous plants, rush-like or bamboo-like in overall appearance. They belong to a group of monocotyledons that includes several similar families, such as the sedges, rushes, and true grasses. They have green, photosynthetic stems and leaves that have been reduced to sheaths. Their flowers are extremely small and in spikelets, which in turn make up the inflorescences. Male and female flowers are on separate plants and, like grasses, are wind-pollinated.

Distribution

Plants in the family are distributed on all the southern continents - South America (1 sp., Apodasmia chilensis), Africa south of the Equator and including Madagascar (about 330 spp.) and Australia (about 150 spp.) - in New Zealand (four spp.) and widely distributed in Southeast Asia (one sp.). They are often dominant elements of the flora in the Mediterranean climates of South Africa and Western Australia. They are the defining family in the Western Cape fynbos plant community.[3] The South American species is very similar to one of the New Zealand species, leading to the conjecture that it might have crossed the Pacific in the last 30 million years. The distribution of restios in Africa is irregular, with the same single species occurring in Madagascar, the Democratic Republic of the Congo, Tanzania, and Malawi, while a different species is found in the Chimanimani Mountains of eastern Zimbabwe. Four species are found in the Natal Drakensberg, one of which spills over into Mpumalanga and Limpopo provinces. The vast majority of species, though, are to be found in the Cape Floristic Region and particularly plentiful on hard sandstone formations. The center of diversity lies in the Kogelberg, where more than a third of all Restionaceae may be found.[4] Restionacea can be found in Kirstenbosch, Cape Town's National Botanical Gardens.

A number of the largest African species have become popular as garden ornamentals in many parts of the world, some being useful as accent plants similar to small species of bamboo, but with pendant stems of greater delicacy. Also, many smaller species offer a great variety of decorative features and deserve horticultural attention.

Classification

The Restionaceae family has been recognized by most taxonomists. The AP-Website [May 2006] assumes 58 genera and 520 species, which agrees well with the Flora of China.

The APG II system of 2003 (unchanged from the APG system, 1998), recognizes this family and assigns it to the order Poales, in the clade commelinids of the monocots.

The Cronquist system of 1981 also recognized this family and placed it in the order Restionales, in the subclass Commelinidae in class Liliopsida in division Magnoliophyta.

Genera

The genera in the Restionaceae are:

Alexgeorgea, Anthochortus, Apodasmia, Askidiosperma, Calopsis, Calorophus, Cannomois, Ceratocaryum, Chaetanthus, Chondropetalum, Chordifex, Coleocarya, Dapsilanthus, Dielsia, Dovea, Elegia, Empodisma, Eurychorda , Harperia, Hydrophilus, Hypodiscus, Hypolaena, Ischyrolepis, Lepidobolus, Leptocarpus, Lepyrodia, Loxocarya, Mastersiella, Meeboldina, Megalotheca, Nevillea, Onychosepalum, Phyllocomos, Platycaulos, Restio, Rhodocoma, Sporadanthus, Staberoha, Thamnochortus, Willdenowia, Winifredia.

References

  1. ↑ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. Retrieved 2013-07-06.
  2. ↑ Bremer, K. (2002). "Gondwanan Evolution of the Grass Alliance of Families (Poales)." Evolution, 56(7): 1374-1387.
  3. ↑ Linder, H. Peter; Pia Eldenas; Barbara G. Briggs (2003). "Contrasting patterns of radiation in African and Australian Restionaceae". Evolution 57 (12): 2688–2702. doi:10.1111/j.0014-3820.2003.tb01513.x. PMID 14761050.
  4. ↑ Restios of the Fynbos - Els Dorrat Haaksma, H. Peter Linder (Botanical Society of South Africa, 2000)

External links

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