Opuntiads of the USA

(by Joe Shaw and Dave Ferguson)

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Opuntia Country with
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Cylindropuntia viridflora (Britton & Rose) F.M.Knuth

At one time Cylindropunta viridiflora was treated as a variety of Opuntia whipplei (var. viridiflora); still others treated the taxon as a variety of C. imbricata. The Flora of North America online does not recognize C. viridiflora in its treatment of Cylindropuntia. CactiGuide reports that the New Cactus Lexicon (DH Books, 2006) does not recognize the taxon. Others treat the plant as a naturally occurring hybrid (ie, Cylindropuntia x viridiflora), see The Cactus Family (Edward Anderson, Timber Press, 2001.

We favor the idea that C. viridiflroa is a stand-alone species in its own right as was described by Britton and Rose (The Cactaceae, Volume 1, 1919, pg. 55, The Carnegie Institution of Washington, Gibson Brothers Press, Washington DC).

Is Cylindropuntia viridiflora a species?

By Dave Ferguson, 2010

Cylindropuntia viridiflora is confused in the literature, and many botanists do not understand what it is. It grows only in the Santa Fe-to-Espanola area of New Mexico where it grows on gravelly hillsides (often alongside C. imbricata and sometimes within a few miles of C. whipplei). [Note: One recent report demonstrates that plants similar to C. viridiflora are found in Arizona; Mugaburu D, Haseltonia 15:108-116, 2009]

C. viridiflora forms populations in New Mexico that reproduce primarily by seed. There is little variation within and between the populations, but flower color does vary. Some blooms are greenish, whereas some are brick red with hints of purple. Most have flowers that are a brassy orange with green highlights. Spine color varies less, and spines are dull light-brown or slightly brown-pink in color (even with the sheath on). Fruits have a distinctive look, like C. imbricata fruits. Seed set is heavy, and seeds look like those of most any other Cylindropuntia.

There are places where C. whipplei and C. imbricata grow together (very few places--mostly where Native Americans planted C. imbricata within the range of C. whipplei). These places often have hybrid plants that seem to usually be of reduced fertility (few or no seeds). They are highly varied in stature, habit, spination, and flower color, and tend to have loose spine sheaths that look pinkish, silver, or yellowish, which can make the plants quite attractive. I have seen several of these places where hybrids occur, but none of the hybrid plants look precisely like C. viridiflora.

In summary, C. viridiflora from the Santa Fe area behaves as a good species, stable, reproducing primarily by seed, and distinct; however, it may have indeed developed through hybridization long ago.