Most growers of small Opuntiads tend to favour plants from the genera Tephrocactus, Maihueniopsis and Cumulopuntia. For some reason, whether space or spikiness, plants of the genus Corynopuntia are less favoured. This is a pity and in this article I hope to show you a selection of plants that are well worthy of being in your collections.
Corynopuntia was first used by Knuth in 1936 to encompass Opuntia which had distinct club-shaped segments. Earlier (and more recently!) these had been considered as Grusonia; however, the latter genus is now monotypic, the sole survivor being G. bradtiana, but that is another story. Corynopuntia occur in habitat predominantly in the south-western states of the USA and the northern states of Mexico. Perhaps this also explains why they are not more widely seen in collections, for collectors in these regions in the past would have always focused on more worthy plants rather than “just another Opuntia”!
There are two other genera (and two plants) that now fit within the scope of Corynopuntia, these being Marenopuntia marenae and Micropuntia pulchella. I will not cover these in this article but they are both distinctive and well worth growing too. So for now, I’ll just choose five of my favourite Corynopuntia sensu stricto.
This plant is the type species of the genus Corynopuntia, and clavata also means club-shaped (a modern tautology arising from the original name of Opuntia clavata being superseded by Corynopuntia clavata!). This species remains low to the ground (<15cm) and will become considerably wider than tall. Rather than describe its characteristics in detail, it is easier to observe it (Fig. 1); note the very characteristic coloration and spatial arrangement of the spines. This is not a vigorous grower for me, adding only a few segments each year, and I have never flowered it in our UK climate.
Fig. 1. Corynopuntia clavata
Corynopuntia bulbispina is one of the tidiest species of the genus, after ten years or so becoming a neat, low growing mound about 20cm across (Fig. 2). It also has the smallest segments (1-2cm long) of all the species. If you are lucky, it will produce bright yellow flowers in summer. The trick with this plant and other Corynopuntia is to start watering it in February/March before any new shoots appear. (This is in start contrast to say most Maihueniopsis from which you should withhold water until May/June (if you dare!) until buds appear – watering these latter plants too early will, in my experience, just result in vegetative growth.) A closely related species is Corynopuntia moelleri, which in my hands has larger segments (3-4cm long) and a more lax habit.
Fig. 2. Corynopuntia bulbispina
This plant is similar in shape and size to C. clavata but tends to have weaker spines (brown and white in colour) and its body can develop rather nice hues of green and purple in sunny summers, providing rather a nice contrast to related plants. The plant I illustrate here (Fig. 3) I acquired as C. stanlyi, now considered synonymous with C. emoryi.
Fig. 3. Corynopuntia emoryi (C. stanlyi)
Corynopuntia invicta is the “big daddy” of the genus and is quite unmistakable; though from a distance (and when not in flower) it can look like a clump of Echinocereus! Today you still often see this for sale as Opuntia (or Grusonia) invicta. Its segments can be anything up to 10-12cm long (though more commonly 6-8cm). The spines on old segments are quite dull and grey in colour but new segments are bright and have distinctive red spines (Fig. 4). The flowers of this species are also yellow (Fig. 5), up to 5cm across, and the spiny floral remains will persist and stay attached to the plant for several years. This is a must for your collection, but it is a literal “pain to re-pot”!
Fig. 4. Corynopuntia invicta
Fig. 5. Corynopuntia invicta, the same plant closer-up
Closely related to C. clavata is C. parishii, again with slightly weaker spines especially when young. Like C. invicta the new segments are considerably brighter and have more colourful spines than more mature segments. The illustration (Fig. 6) shows a young plant started from rooting down a single segment a couple of years earlier.
Fig. 6. Corynopuntia parishii, a small plant
Hopefully, this brief survey will encourage you to seek out some specimens of this genus to add to your collection.
This article was originally published in Tephrocactus Study Group (the 'TSG Journal'), September 2012, Vol. 18, No. 3, pages 32-33 and 35-37. © TSG and Tony Roberts. It is reproduced here with the permission of the author.