The foveola of Bothriochloa alta (Poaceae: Andropogoneae): Extrafloral nectary or secretory gland of essential oils?

SCRIVANTI L.; BERNARDELLO G.; ANTON A. M.

FLORA

Elsevier

Año: 2008 vol. 203 p. 55 - 59

0367-2530

In some Bothriochloa species, the foveola or pit -a depression located in the lower glume of the sessile spikelet-, has been interpreted as being an extrafloral nectary, although neither the structure has been studied nor the secretion detected. On this basis, we analyzed the characteristics and structure of the foveola and the chemical composition of the secretion in Bothriochloa alta (Hitchc.) Herter, a grass with disjunt distribution from North and South America. In parallel, inflorescence visitors were identified during three summers (2003 to 2005) in populations from the Province of Córdoba (Argentina). The results show that the foveola functions as a secretory cavity producing essential oils instead of being an extrafloral nectary as previously suggested. The main compounds identified as components of the oils included ester methyl linoleate (34%), and two oxygenated sesquiterpenes: tau-cadinol (23.3%) and 6-methyl-alpha (E)-ionone (9.8%). Several species of Coleoptera, Hemiptera, and Diptera are inflorescence visitors.