Publication: Kaktusy (Brno) 32: 98, fig. 1996 25108
Description
Demnozas grow slowly and stay globulous during a long period before becoming shortly column-shaped, 0.5 to 1.5 cm high. The plant’s diameter ranges from 15 to 30 cm, the stem colour varies from pale green to dark green, with 15 to 30 ribs. They need to reach a reasonable size in cultivation before producing their flowers. First flowers appear, however, on plants of very unequal age and size, some time on relatively young plants but also on 30-40 years old specimens! Flowers are zygomorphous, of a maximum length of 7.5 cm, reddish in colour and have white hair on the tube. The flower open sufficiently widely so that the stigma and stamen are visible from outside.
Origin and Habitat
Praeruptus alveus fluminis Rio Diamante, ad Agua Del Toro, 800-900 m, Mendoza (Argentina)
Cultivation and Propagation
Denmoza rhodacantha is very slow growing cactus but requires no special condition in cultivation, need full sun and a very draining soil.
Notes
The genus Denmoza comprises only one species. The plants described as Pilocereus erythrocephalus and later transferred to Denmoza has sometimes, for instance by Backeberg, been considered as another species of the genus. Denmoza rhodacantha changes considerably in the habit with age. The description of Denmoza rhodacantha refers to young plants having strong spines in areoles. Old plants of the same species with multiple number of spines and sometimes with thin, 6 cm long bristly spines correspond to the description of Denmoza erythrosepala.
