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LIFE‐HISTORY STRATEGIES AND SEX RATIOS FOR A CULTIVAR AND A WILD POPULATION OF BUCHLOE DACTYLOIDES (GRAMINEAE)
Author(s) -
Quinn James A.,
Engel Jean L.
Publication year - 1986
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.1537-2197.1986.tb12125.x
Subject(s) - biology , perennial plant , cultivar , population , sex ratio , stolon , botany , plant reproductive morphology , dormancy , agronomy , germination , poaceae , horticulture , demography , sociology
Buchloe dactyloides (Nutt.) Engelm. is a perennial, sod‐forming shortgrass of the grasslands of central North America from Montana to northern Mexico. The objectives of this research were to compare a cultivar (Sharps Improved) and a wild population from the Oklahoma panhandle, both in the field and in the greenhouse over several growing seasons, in regard to life‐history strategies, sex ratios, and constancy of sex expression. Sex ratios of offspring from individual burs (usually 1–5 seeds per bur) and for all surviving plants germinated from seeds in the greenhouse were markedly different for the two populations. The wild population exhibited a 1: 1 male/female ratio with no monoecious plants and complete stability in sex expression over 3 yr of study in the greenhouse. In contrast, 13% of the cultivar plants were monoecious, and its unisexual plants showed a female bias. Burs of the two populations, in flats exposed to three separated month‐long periods of favorable moisture with intervening “drought” periods, showed differential germinability of seeds within burs. The cultivar had less dormancy and produced a greater number of seedlings in the first and second periods; wild burs significantly exceeded cultivar burs in the number of seedlings during the third period and in the number of burs giving rise to seedlings in all three periods. Field and greenhouse measurements of vegetative (VRE) and sexual reproductive effort (SRE) per plant indicated that SRE was minimal (ca. 2% of aboveground biomass) in relation to asexual ramet propagation by rapidly growing stolons (VRE = ca. 80%). Mean SRE and VRE were not only similar for the populations, but also for the males and females within a population, although the values for individual plants were highly variable. It is concluded that Buchloe dactyloides is largely dioecious, with at least some wild populations showing a 1: 1 male/female ratio and constancy of sex expression, and that the bur as a dispersal unit containing 1–5 seeds is particularly appropriate for the breeding system and habitat ecology of Buchloe dactyloides.