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FLORAL PARAMETERS, BREEDING SYSTEM AND POLLINATOR TYPE IN TRICHOSTEMA (LABIATAE)
Author(s) -
Spira Timothy P.
Publication year - 1980
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1980.tb07652.x
Subject(s) - biology , pollinator , outcrossing , selfing , pollination , pollen , nectar , botany , ovule , zoophily , stamen , pollen source , outbreeding depression , inbreeding , population , demography , sociology
Diversity in flower size and degree of exsertion of anthers and stigma from the corolla in the California species of Trichostema appear to be correlated with breeding system and pollinator type (bee vs. bird). Autogamous (self‐pollinating) species unlike xenogamous (cross‐pollinating) species lack spatially separate anthers and stigma and nototribic pollination. The outcrossing species have significantly larger flowers, significantly larger nectar volumes and significantly higher pollen‐ovule ratios than do selfing species. Because autogamous species are less reliant on flower visitors to facilitate pollination, there may be relaxed selection for large nectar producing flowers. Pollen‐ovule ratios are correlated with breeding system and reflect the efficiency of pollen transport. Data on floral parameters suggest xenogamous species expend more energy per floral unit and are less efficient seed producers than closely related autogamous species.