Dicrocaulon
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Dicrocaulon is a genus of plants fromthe afternoon flower family (Aizoaceae). The botanical name of the genus is derived from the Greek words "dicros" for fork and "caulon" for stem .
description
The species of the genus Dicrocaulon grow shrubby with upright, ascending or prostrate shoots and reach heights of up to 50 centimeters with diameters of up to 30 centimeters. The main shoots sometimes reach up to 3 centimeters in diameter. The internodes are usually thin. The species sometimes form elongated long shoots and short side shoots. Side shoots can transform into long shoots and vice versa. The shoots are variegated. The long shoots produce two pairs of leaves or more each year , while the short shoots only have two pairs of leaves. The first pair of leaves is always two thirds of its length fused together and forms a spherical to egg-shaped, bilobed body. If only one additional pair of leaves is formed on long shoots, it is at least five times longer than the first pair of leaves and only fused together over a fifth of its length. Otherwise, the pairs of leaves are only three to five times as long as the first. Their shape and the degree of adhesion can be different.
The individual, stalked flowers appear from the gap at the tip of the last pair of leaves. There are 4 to 6 sepals available. The petals are white, pink, purple or red. Thread-like staminodes are missing or present.
The flat capsule fruits are 4- to 9-compartment and have no closure bodies. They contain light brown to whitish, mostly papillary seeds .
The chromosome number is 2n = 18, 36.
Systematics and distribution
The distribution area of the genus Dicrocaulon extends from the west of the Namaqualand in the South African province of North Cape to the places Vanrhynsdorp and Vredendal in the province of Western Cape . The plants grow on flat soils that are covered with quartz gravel or in crevices. The annual rainfall is less than 200 millimeters, with the majority falling in winter.
The first description was published in 1928 by Nicholas Edward Brown . The holotype is Dicrocaulon nodosum . According to Hans-Dieter Ihlenfeldt (* 1932) the genus Dicrocaulon includes the following species:
- Dicrocaulon brevifolium N.E.Br.
- Dicrocaulon grandiflorum Ihlenf.
- Dicrocaulon humile N.E.Br.
- Dicrocaulon microstigma (L.Bolus) Ihlenf.
- Dicrocaulon nodosum (A.Berger) NEBr.
- Dicrocaulon ramulosum (L.Bolus) Ihlenf.
- Dicrocaulon spissum N.E.Br.
proof
literature
- Heidrun EK Hartmann (Ed.): Illustrated Handbook of Succulent Plants: Aizoaceae AE . Springer Verlag, Berlin / Heidelberg / New York 2001, ISBN 3-540-41691-9 , pp. 211-212 .
- Gideon Smith et al. a. (Ed.): Mesembs of the World: Illustrated Guide to a Remarkable Succulent Group . Briza Publications, 1998, ISBN 1-875093-13-3 , pp. 234-235 .
Individual evidence
- ^ Journal of Botany, British and Foreign . Volume 66, p. 141, London 1928
- ↑ Heidrun EK Hartmann (Ed.): Illustrated Handbook of Succulent Plants: Aizoaceae AE . Springer Verlag, Berlin / Heidelberg / New York 2001, ISBN 3-540-41691-9 , pp. 212 .
further reading
- H.-D. Ihlenfeldt, H. Hartmann, H.-H. Poppendieck: Chromosome numbers of the Mitrophyllinae Schwantes (Mesembryanthemaceae) . In: Messages from the Institute for General Botany . Volume 16, pp. 171-182, Hamburg 1978