The Botany of Salvia divinorum (Labiatae)

Title: The Botany of Salvia divinorum (Labiatae)
Author: A.S. Reisfield
Publication date: 1993
Journal: SIDA (now The Journal of the Botanical Research Institute of Texas)

http://www.sagewisdom.org/reisfield.html (Linked from Daniel Siebert's site; web version with many photos)

Abstract
Salvia divinorum, ceremoniously employed by the Mazatec Indians of Oaxaca, is endemic to the sierra inhabited by the Mazatec, its distribution anthropogenic. Plants spread vegetatively, flourishing in shaded, humid sites, flowering sporadically from October until June. Flower nectar and corolla dimensions suggest ornithophily, and the only pollination event observed involved a single hummingbird, but other factors suggest that visits by birds to the flowers in their present range are opportunistic, and not a product of plant-pollinator co-evolution. The species is diploid with n=11, pollen fertility is reduced, there is no active pollen tube inhibition within the style, but some event or process after the pollen tube reaches the ovary is aberrant, as no fully developed nutlet has ever been collected from a Mexican plant, and greenhouse cross-pollinations led to only 3% seed set. Hybridity is suggested, although intermediacy between two known species has not been recognized.