Reproductive biology of Monttea aphylla (Scrophulariaceae)

M. TADEY

AUSTRALIAN JOURNAL OF BOTANY

CSIRO PUBLISHING

Año: 2011 vol. 59 p. 713 - 718

0067-1924

Monttea aphylla (MA) is a shrub abundant in the Monte Desert, Argentina. This species presents particular floral syndromes including violet, tubular flowers with trichome elaiophores that produce oil. Oil flowers are associated with specialised bees with an oil-collecting apparatus. To understand the reproductive biology of MA, the mating system, flowering phenology, the associated pollinator assemblage and foraging behaviour was determined at the southernmost part of its distributional range. Results were compared with those of previous studies and discussed. At this southern location MA is a self-incompatible species; it relies on pollinators for fruit production and presented a low fruit set. Flowering occurred during the spring, from October to December. MA was pollinated by three species of bees; two generalist species (Centris brethesi and Mesonychium jenseni) and one specialist to MA (Centris vardyorum). M. jenseni is a cleptoparasite of Centris species. Centris species are oil-collecting bees and showed territorial behaviour (i.e. they always visited a restricted group of plants which they protected from other visitors), they visited several flowers/plants, which enhanced geitonogamous self-pollination and reduced pollination efficiency, and which might explain the low natural fruit set observed in MA. C. vardyorum was the most important pollinator of MA in the study area. The reproductive biology of MA differs along its distributional range. Apparently, southern populations of MA are more specialised than the northern populations, the former being pollinated by a few related pollinator species whereas at the northern location a variety of visitors were observed.