Recent collections by Dr. C. H. Dodson of the Marie Selby Botanical Gardens staff at several sites of intensive floral investigation (florula) in western Ecuador have provided me with a number of novelties of the Bromeliaceae including this first instance of natural hybridization in the subfamily Pitcairnioidae. Four specimens from the Province of Cotopaxi seem certain to represent members of a hybrid swarm involving two sympatric, ornithophilous lithophytes, Pitcairnia heterophylla (fig. 13A), and P. pungens (fig. 13D).
Pitcairnia heterophylla (Lindley) Beer is a common species ranging widely from central Mexico to Venezuela and Peru. The densely flowered inflorescence is nearly sessile. Flower color varies from white (forma albiflora Standley & Smith) to pink and red. In western Ecuador, the pink-flowered phase is most abundant. While usually found growing on rocks, many plants also occur as epiphytes. Their altitude range varies from 50 to nearly 2300 m, but where P. heterophylla grows near P. pungens it seems to favor elevations below 1500 m.
Pitcairnia pungens Humboldt, Bonpland & Kunth has a much more restricted distribution, having been found from Colombia to central Peru. The much exserted, racemose inflorescence is in marked contrast to P. heterophylla. Flower color varies from yellow-orange to dark red. The recorded altitude range varies from 800 to 3500 m; the majority of the specimens I have examined were collected above 1700 m.
In the steep valley of the Rio Pilalo at Tenefuerte, an area of rich premontane forest, these two species are growing apparently within the foraging range of a shared hummingbird pollinator. Most of the specimens seen from this site fall somewhere outside the accepted range of variation, appearing to be part of a hybrid swarm. The nearly vertical rocky roadside and cliff face seem to provide the conditions required by the hybrid plants. Individuals suspected to be of hybrid origin produce abbreviated scapes with variable flower color. Also present are superficially pure plants of P. pungens and P. heterophylla. The percentage of pollen viability has not been tested, but several specimens of the purported hybrids show developing capsules. I suspect that hummingbirds service the hybrids as well as the parent species.
In the light of this new information, I suggest that P. pavonii Mez be investigated very carefully. That species is distinguished by its much broader leaf blades, but appears to be similar in its shape and size of inflorescence to the hybrid just described. —SeeJ. Bromeliad Soc.
