Coryphantha is one of those genera that everyone knows, and probably has at least a few plants in their collection. They mostly come from Mexico with a few species from the southern states of the USA. Some American authorities include many Escobaria species, which could then extend their distribution up into Canada with the most northerly form of Escobaria vivipara. Here in the UK, we tend to leave those in Escobaria, separated mostly on the basis of seed structure.
Fig 1 Two Coryphantha. Left: C pseudonickelsae Right: C glassii
These large-flowered relatives of Mammillaria are easily distinguished, in most of the recognised species, by a groove that either fully or partly joins the areole and the axil at the base of the tubercle. The tubercles are usually far broader and longer than those of Mammillaria, and the flowers tend to be apical, from the current year’s growth. Some species have very well developed glands, or extra-floral nectaries, in the axils, often red in colour. The seeds are reticulate, meaning the surface is criss-crossed, like a net.
Cultivation is relatively straightforward, but as the plants in habitat tend to grow on flat or gently sloping grassy areas, sometimes partly shaded, it has been suggested that plants in our greenhouses might benefit from good root-room, and also perhaps are more water-hungry that some Mexican species. Flowers come later than many, from June to August, often in several flushes and, although most are yellow, some species have beautiful pink to almost purple flowers. They can be susceptible to red spider, and also mealy bug, though the latter is relatively easy to identify while with red spider the damage is often done before one sees the cause.
Fig 2 Coryphantha cornifera
C cornifera is one of my favourites, and has large wide open yellow flowers, but remains solitary. The plant shown flowers regularly in early July and usually has three or four flowers that open together, or within a few days of each other. It is a species that one would normally associate with a dark curved central spine.
Identification of Coryphantha species can be quite a difficult task, as many species have two very distinct growth phases. The juvenile phase is one which can last up to five years or so, after which the plants start to develop their final shape, which can be sub-spherical, spherical or columnar. The adult phase usually starts with the development of the spination of the plant, usually with denser spines or with the development of central spines, or more central spines. However, that is not the whole story as there are a number of species in which the development of any central spines is a variable feast! The plants in our collections tend to be more ‘standardised’ owing to the propagation of relatively few collections.
Fig 3 Coryphantha cornifera in habitat
However, in their native country the variability is much higher, and this has given rise to a myriad of names for some species, including Coryphantha cornifera. As an example, here are two more photos of Coryphantha cornifera, taken in habitat. Both of these photos were taken on the same site to the east of El Cardonal, Queretaro. The plants are about the same size, with about the same number of tubercles, so it is safe to assume that they are of similar age. One plant shows no sign of development of central spine(s), whereas the second plant has a single very stout curved spine from every areole, including those right at the bottom of the plant.
This type of variation can be found in many Coryphanthas, which in some part makes growing from seed a fascinating process. It’s a game of ‘will they, won’t they’ as the plants develop and age. They can be raised from seed fairly easily, and a good range of species is available from Mesa Garden and also continental seed merchants. I would just suggest that one keeps the humidity levels reasonably high for a good while to let the young seedlings develop well.
The flower colour remains much more consistent, and to end this short article, here is an example of a clumping species, with a nice pink flower.
Fig 4 Coryphantha echinus in habitat at Casas Coloradas, Coahuila. Courtesy of www.cactus-house.it
Chris DaviesNo part of this article or the accompanying pictures may be reproduced without permission