Biodiversity

Wednesday, March 14, 2007

RESTIONACEAE

Extracted from Delta data base

The family Restionaceae is a fundamental family within the Cape Fynbos. Members of the family are usually characterized as a reed-like shrub, growing mainly on table mountain sandstones and acid coastal sand. Out of the 350 species in the family, 23 species occur on nutrient rich granites, 21 species are found on shale, 15 species occur on limestone and 8 taxa occur on alkaline sands. These shrubs are predominantly about 1 m in length; however species such as Cannomois grandis may reach lengths up to 5 m. The predominant growth form is tufted, while 22 % are clumped, others are mat forming or tangled and a mere 3 % form isolated shoots. Most species acquire nutrients from low nutrient soils via horizontal rhizomes which are 2- 12 mm in diameter. Some species have stolons or compact root systems without rhizomes or stolons. Members of Restionaceae differ from other Fynbos families in that the leaves are completely reduced to a leaf sheath surrounding the stem. Hence the stem is photosynthetic.

Restionaceae is mainly distributed in the Western Cape, Northern Cape, Eastern Cape of South Africa, as well as parts of Malawi. Main dispersal mechanisms include nuts containing the ovary with seeds. These nuts are normally brown, black or tan and are elliptic in cross section.

These plants are not suitable for grazing; however some may be used for thatching or in horticulture. Compared to other families, 6 % of Restionaceae species are vulnerable, 2.3 % are endangered and 15 % are rare. Willdenowia affinis is the only species that I could find that have gone extinct within Restionaceae.

Fire plays a major role in Fynbos growth and management; hence members of this family generally show fire resistance by being either re-sprouters or re-seeders. In addition, some members of Restionaceae make use of fire smoke as cue for seed germination. Seeds can subsequently fully exploit nutrients re-generated by a passing fire. The intensity, frequency and duration of fire play a pivotal role in Fynbos management.

4 Comments:

  • Very good writing. "Out of the 350 species in the family, 23 species occur on nutrient rich granites, 21 species are found on shale, 15 species occur on limestone and 8 taxa occur on alkaline sands." I noticed that you used the words "species" and "taxa" as if they are the same. I think that taxa are a larger group. Thanks

    By Blogger Eager, at March 14, 2007 2:13 PM  

  • Hey rosie.

    The term taxon does not necessarily mean a bigger group, but simply refers to any level of classification. That is it can be species, genus, family etc.

    mixi.

    By Blogger megan van der bank, at March 14, 2007 4:59 PM  

  • Megan is quite right, taxa refers to any level of classification. In the case of Peter's Restio Database - it would be better to use the word taxa since he has included sub-species. It is therefore more correct to say the key has 350 taxa or species/sup-species that just species. For this assignment this is splitting hairs, but it is good to comment on people's work and for them to get back to you. So good work for both of you - this is the sort of debate that I am wanting.

    By Blogger Rich Knight, at March 14, 2007 5:10 PM  

  • Hey Mixie!

    I enjoyed reading your "crystal clear" writing. In your opening sentence you say that restionaceae is a fundamental family within the Cape Fynbos...Why?

    By Blogger Dane, at March 14, 2007 8:52 PM  

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