Within- and between-population variation in ramet behaviour in the gynodioecious clonal herb, Glechoma hederacea (Labiatae)

Abstract

Clones of the gynodioecious herb Glechoma hederacea L. produce ramets which flower and bear seed, ramets which flower but fail to bear seed, and sterile ramets. Performance and survivorship of these subsets of ramets were compared for hermaphrodite and male sterile clones in contrasting grassland and woodland habitats for 2 consecutive years. For all clones, ramet densities on given dates were comparable between years. Winter survival of ramets exceeded 95% and mortality during the growing season was exponential. No genet recruitment was recorded throughout the study. For all clones, flowering ramets were larger than nonflowering ramets. Both flowering and nonflowering ramets of hermaphrodite clones, from grassland and woodland, were significantly larger than corresponding types of ramets from male sterile clones. A higher proportion of ramets of hermaphrodite clones flowered and set seed than ramets of male sterile clones. Flowering ramets of hermaphrodite clones produced more flowers than flowering ramets of male sterile clones. For all clones, half-lives of subsets of ramets declined in the order: seed-bearing > flowering but not seed-bearing > nonflowering. Within the grassland habitat, ramet subsets from hermaphrodite clones had longer half-lives than corresponding subsets from the male sterile clones. In the absence of greater flowering and seed set by male sterile clones, self-incompatibility of hermaphrodite flowers, which has been reported previously for G. hederacea, is crucial for the maintenance of clones of both sexes in populations.

To compete or not to compete: an experimental study of interactions between plant species with contrasting root behaviour

“…For example, the longevity of Fragaria ramets can be up to 6 years, whereas Glechoma ramets generally survive no longer than a year (Angevine 1983;Slade and Hutchings 1989;Tamm et al 2002). Conversely, specific root length, which is related to the potential resource uptake rate per unit root construction cost (Eissenstat 1991;Wright and Westoby 1999;Eissenstat et al 2000), is 38% lower for Fragaria than for Glechoma (M. Semchenko, unpublished data).…”

“…Ramets consist of two leaves and are borne on branching stolons that usually persist for up to one growing season (Slade and Hutchings 1989). It is a carpet-forming herb with fast vegetative spread; establishment from seed is rare in many habitats (Grime et al 2007).…”

Sex expression, female frequency, and reproductive output in a gynodioecious clonal herb, Glechoma longituba (Lamiaceae)

“…The variability of phenotypic gender resulted from the existence of PMS (partially male-sterile). These PMS or intermediate plants constitute a continuous series, linking complete male sterility (female) and hermaphroditism (Koelwijn and van Damme 1996), such as the pronounced plasticity in stamen fertility adds to the great plasticity found in ramet behavior in G. hederacea (Slade and Hutchings 1989). Thus, there is agreement concerning the occurrence of labile sex expression, but its ultimate significance is questioned.…”

Heavy metals modify costs of reproduction and clonal growth in the stoloniferous herb Potentilla anserina

“…There was no difference in the leaf and root biomass; in contrast, the stolon biomass of flowering ramets tended to be greater than that of non-flowering ramets. Possibly, there is a relationship between probability of flower production and ramet size (Slade and Hutchings, 1988). Ramets may have to reach a certain size before they are able to produce flowers and seeds.…”