干旱区生态环境知识资源中心

Seed production and the recruitment of new individuals are in part related to reproductive traits such as floral behaviour, phenology, production of sexual gametes, nectar, mating and breeding systems, and population densities. We studied the floral biology, nectar production, and pollination of Mammillaria huitzilopochtili D.R.Hunt in ex situ conditions to provide support that can be used to determine extinction risk of the species given its breeding system and reproductive success. Flowering of M. huitzilopochtli covers a four month period (September to December), with diurnal anthesis and a floral longevity of around six days. Nectar production was low (2.02 mu l) and found in 39% of sampled flowers. The species presents a facultative outcrossing breeding system, with a ovule:polen ratio of 1,048. Seed set was highly variable and low (35%) if compared with the mean number of ovules. There are few treatments on floral biology of Mammillaria, but comparing with other Cactaceae, floral behaviour was similar to other bee pollinated species such as Echinocactus, Grusonia, and Opuntia. Floral longevity is longer than reported for other Cactaceae and both the presence of dimorphic nectar production and empty fruits had not been reported previously. The facultative xenogamous breeding system and outcrossing mating system are common in rare cactus species. This condition coupled with the variation in seed set and lack of clonal propagation adds factors towards risk.