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Wednesday, August 29, 2012

Kransplakkie (Crassula sericea)

Family Crassulaceae
Although this plant is not from South Africa, it is very popular in most of our gardens.

Crassula sericea var. sericea is a common cliff-dwelling succulent shrublet in southern Namibia and in the lower Gariep (Orange River) region in the Northern Cape.

Flowering time : Crassula sericea var. sericea flowers mainly during Winter (May–August).

Distribution and habitat

Crassula sericea var. sericea is found in the lower Gariep (Orange River) Valley from Kakamas in the east to the Richtersveld (Northern Cape, South Africa) in the west and in the Hunsberg, Karasberg and Witputz regions of Namibia. The plants are confined to sheer cliff faces, up to about 800 m in altitude, where they grow in crevices with shallow soil, mainly on quartzitic sandstone rock formations. Temperatures in the region are high during summer and mild in winter. Rainfall in the western Richtersveld region occurs mainly during winter (cyclonic winter rain) and in the eastern part (Bushmanland) mainly during summer. It ranges between 75–250 mm per annum. Plants grow on shady rocky ledges in shallow soil. The associated vegetation consists of Succulent Karoo and Desert biomes. The Richtersveld and the adjacent territory is a centre of endemism for the family Crassulaceae to which the species belongs (many species are confined to this region). In the upper reaches of the Gannakouriep River (Ai-Ais Richtersveld Transfrontier National Park) Crassula sericea var. sericea was found growing with other cliff-dwelling succulent plants such as Tylecodon ellaphieae, Aloe meyeri, Bulbine pendens and Ornithogalum suaveolens.
 Derivation of name and historical aspects

Crassula sericea var. sericea was named by Selmar Schonland in 1910 from plants collected by the German plant explorer, Rudolph Schlechter. The Latin epithet 'sericea', pertains to the dense silky hairs on the leaves of the species.

Crassula sericea var. sericea is one of about 170 Crassula species occurring in South Africa and Namibia, and belongs to the Stonecrop family (Crassulaceae). It is closely related to C. sericea var. velutina and C. sericea var. hottentotta. Crassula sericea var. velutina has larger flattened leaves with velvety hairs and flowers from September to November (Spring flowering). Crassula sericea var. hottentotta has rounded leaves similar to those of var. sericea but not brittle and it can also be distinguished by its leaf surface which bears coarse rounded papillae, and is thus not hairy as in the other varieties. The plants also flower during winter (June–August).

Plants have a clustered and compact growth against the cliff (cliff hugger) and are well adapted to the sheer habitat. They are winter growers, the leaves are brittle and when becoming dislodged, will root in crevices establishing new clones. The grey-green very succulent leaves covered with short spreading hairs are an adaptation to the dry habitat. The small white flowers are pollinated by insects.

Uses and cultural aspects

No uses have been recorded.
Information from: