Plectranthus (Plectranthus cataractarum)
|Size||Height: 20 - 40 cm (2)|
Leaf length: up to 7 cm (2)
Leaf width: up to 2.5 cm (2)
Classified as Vulnerable (VU - A2c, B2ab(ii, iv, v); C2a(i); D2), under IUCN Red List categories (3).
This small herb is unusual amongst the mint family (Labiatae) as it is one of a very few species that occupies habitats in and around water (2). This specialisation is reflected in the specific name of cataractarum, which means 'of waterfalls' (2). The stems are often seen growing along, or climbing up, rocks and stones; the single inflorescence (or flower stalk) is unbranched and has a fine covering of white hairs (2). The small leaves are fleshy with bluntly-toothed outer edges (2). At the end of the inflorescence, there are between 6 - 8 whorls of flowers, each consisting of up to 14 small mauve or white flowers (2). Plants are often seen together, forming large clumps growing upon rocks at the edge of waterfalls; these clumps may be up to 3m² in area (2).
Found in West Africa: on Mount Cameroon and the Bakossi Mountains in Cameroon, and also known from Equatorial Guinea (2).
Plectranthus cataractarum inhabits the spray zone of waterfalls, on wet rocks in lowland or submontane evergreen forests (2). Plants have been recorded from sites that are between 300 and 1,450 metres above sea level (2).
Flowering and fruiting begin towards the end of the rainy season, in October and November, and extend into February (2). These plants are usually seen growing upon rocks and stones in large groups (2).
In Cameroon, this species is threatened by the clearance of its natural forest habitat to make way for oil palm plantations; Plectranthus cataractarum may already be extinct from one site on Mount Cameroon where the forest has been lost (2). This species is also threatened by the small area of its occurrence, possibly not more than 5 - 10km², which makes its future inherently vulnerable (2).
This unusual species was only discovered as recently as 1998 and despite threats from deforestation, it has a fairly wide distribution. Additional security is gained by the fact that some sites are too high to be threatened by plantation development (2). The Ministry of Environment and Forests has proposed a forest reserve in Cameroon, which would encompass one of the sites of Plectranthus cataractarum in the Bakossi Mountains (2).
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- Herb: a small, non-woody, seed bearing plant in which all the aerial parts die back at the end of each growing season.
- Inflorescence: the reproductive shoot of the plant, which bears flowers (See http://www.rbgkew.org.uk/ksheets/pdfs/flower.pdf for a fact sheet on flower structure).
- Whorls: in animals, the spiral or convolutions in the shell of a snail. In plants, a set of leaves, flowers, or branches that spring from a stem at the same point and encircle it.
IUCN Red List (December, 2009)