februari 2013 nummer 1

Summary
Rob Bregman
This first 2013 issue is opened by editor Henk Viscaal, who looks back at the time
that he was selling cacti on the market.
Theo Heijnsdijk deals with Crassula (Rochea) falcata, a leaf succulent from the
Cape region, which has been in culture for over 3 centuries now. The author explains
the special leaf surface morphology, in that the epidermal cells produce large
vesicle-like protuberances in order to minimize evaporation. The plants hybridize
easily with other Crassula species, so many cultivars are available.
In his ongoing series, Bertus Spee presents short descriptions and recommendations
for cultivation of 4 nice succulents, viz. Thelocactus bicolor ssp. bolaensis,
Puna bonnieae, Parodia haselbergii (with yellow flower!) and Aloe krapholliana.
Our co-editor and Gymnocalycium specialist Ludwig Bercht is put in the spotlight
by Jan Jaap de Morree. Ludwig has been selling seeds from 1983 on, predominantly
obtained from his impressive collection, which for the greater part is the result
of sowing seeds he collected in South America.
Ludwig himself presents part 22 of his series of articles on the genus
Gymnocalycium. In this part the type species of the genus G. gibbosum is dealt
with. This is a very variable species, so that many subspecies, varieties and forms
have been described.
Ben Zonneveld and the late Ton Pullen continue their series on the genus
Cotyledon with C. barbeyi, a species with an extensive distribution area ranging
from Ethiopia to eastern South Africa. It is not common in European collections.
A contribution by Herbert Thiele is devoted to Neowerdermannia, a genus from
high Andine regions in central South America. Two species have been described,
with several local forms. The plants are best cultivated in maximum light and fresh
air. Seeds germinate best with great day-night temperature differences.
Frans Noltee reports about 3 Crassula species (C. nemorosa, C. saxifraga and C.
umbella) with subterraneous tubers, all from the Richtersveld, South Africa.
Johan Pot comments to the modern species concept, which says that plants belong
to the same species if they mutually interbreed, whereas morphological features
are of less importance. To soothe him, I commented that morphology still
remains essential.
Ben Zonneveld outlines the genetic background of yellowish leaves in Jovibarba
heuffeli (Crassulaceae). By crossing and selecting, he created yellowish plants that
turn red instead of green.
Hector Petersenstraat 7
1112 LJ Diemen
R.Bregman@contact.uva.nl
©Succulenta jaargang 92 (1) 2013 47