Argyroderma
Argyroderma sp. in the Knersvlakte
Argyroderma is a plant genus of the family of Mesembryanthemum plants ( Aizoaceae ). The botanical name of the genus is derived from the Greek words ἄργρος ( argyros ) for " silver " and δέρμα ( derma ) for " skin " and refers to the silvery gray-green leaves of the plants.
Description
The plants of the genus Argyroderma are perennial plants that grow grass making up compact. In some species the leaves are reduced to a single pair of leaves. Some species grow sunk into the ground. The silver to gray- green, opposite leaves are finger to thumb- shaped and more or less rounded. The leaf pairs are fused together at the base. Her smooth epidermis is not dotted or warty and has deeply sunken stomata. The epidermis is composed of cells with very thick walls and contains a thick layer of crystal sand. Old leaves often remain on the plants for several years.
The single, stalked, yellow, purple, red or rarely white flowers have bracts and a clear flower cups 2-4 millimeters in length. Your 6-8 sepals are fused into a short tube. The standing in a dense ring stamens are bent inward and hide the left at the top of the ovary small, ring-shaped pillow made of fused scars. The 10 - to 24 - fächrigen capsule fruits resemble those of the genus Leipoldtia, but have rather narrow flap wings. The flower cups remains until the next rainy season at the capsule. Smooth brown seeds are more or less rounded, and 0.5 to 0.85 mm long and 0.35 to 0.65 mm wide.
The heyday of the plants begins in her home in April and extends into June. The flowers open at midday and close in the evening.
Systematics, chromosome number and distribution
The distribution of the genus Argyroderma is in the northwest of the South African Western Cape Province in the semi-desert Knersvlakte and extends from Vanrhynsdorp way to Vredendal. The plants growing on quartzite containing layers or on slopes, rarely on sandy or slightly salty plains. The annual rainfall is below 200 mm, with the majority falling in the winter.
The chromosome number.
The first description was published in 1922 by Nicholas Edward Brown. The type species is Argyroderma testiculare. After Heidrun Hartmann ( b. 1942 ), the genus is divided into two subgenera and include the following types:
- Subgenus Argyroderma Argyroderma congregatum
- Argyroderma crateriforme
- Argyroderma delaetii
- Argyroderma framsii Argyroderma framsii subsp. framsii
- Argyroderma framsii subsp. hallii
- Subgenus Roodia Argyroderma fissum
Furthermore, the hybrid Argyroderma × octophyllum belongs to the genus.