Note: This page is a Work In Progress. Photographs to be added!
At the last TSG AGM in May I suggested that the Journal coverage should be extended to cover smaller North American Opuntias. This would avoid repetition of articles on South American Opuntias and, hopefully, appeal to those members who grow a range of species from both continents.
The North American genus Micropuntia consists of dwarf simple or cushion forming plants with long branching tap roots and generally thin cylindrical stems. The short spines are slender and flexible and the flowers are apical. They have many similarities with the South American genus Pterocactus, but lack the “winged” seed that gives the latter its generic name.
When Backeberg’s published English edition of the Cactus Lexicon was produced in 1976, the validity of the genus was in dispute. Daston gave the absence of glochids as a characteristic of the genus, but even this was dubious. Some authorities considered that Micropuntia should be sunk beneath Corynopuntia pulchella (Eng.) Knuth that has similar floral characteristics, but this species supposedly had long glochids and clavate (club-shaped) stem segments.
All species of Micropuntia have pink flowers that tend to last no more than two days.
At one time it was considered advisable to graft all species, but this is no longer necessary provided a gritty compost is used so as not to inhibit the root development.
In the UK Micropuntias seem to grow particularly well outside a greenhouse environment and the stems then seem to take on an attractive deep pink colour. The plants are watered between March and late September, as are all cacti in the author’s collection. In addition they are fed twice a year with a compound feed containing no more than 5% nitrogen. Backeberg lists six species of Micropuntia - M. barkleyana Daston, M. brachyrhopalic Daston (Type), M. gracicylindrica Weigand & Backeberg (Fig. 1), M. pygmae Wiegand & Backeberg, M. weigandii Backeberg and the delightfully named M. tuberculosirhopalica Wiegand & Backeberg (Fig. 2). In my long association with Opuntias I have only ever seen three of these listed species for sale.
It would appear that all species originate from Utah, Nevada, California and N.W. Arizona.
In the New Cactus Lexicon, recently compiled by the International Cactaceae Systematics Group, all species of Micropuntia are sunk in Corynopuntia pulchella (Eng.) Knuth (Fig. 3) with which they have significantly similar root, spine and floral characteristics.
John Betteley. Newark.