Comparative reproductive ability of bigtooth and trembling aspen and their hybrid

Abstract

Populus tremuloides and P. grandidentata hybridize readily in southeastern Michigan, and gene flow may be occurring that could alter the parent populations. The purpose of the study was to compare the reproductive capacity and initial growth of hybrids with that of the parent species. Seed-bearing branches of clones of each taxon were collected in nature, and seeds were obtained for growth comparisons. The hybrid clones were lower than the parents in some reproductive traits and intermediate in others. The hybrid exhibited significantly lower seed production per shoot than the parents although some hybrid clones produced more seeds per shoot than certain parental clones. Seed germination percentage of hybrid clones was significantly lower than that of the parents, although individual hybrids had higher germination percentages than some parental clones. Initial height growth of hybrid progeny was somewhat greater at 4 weeks, but was somewhat less than progeny of both parents at 18 weeks. Although the hybrid exhibited some-what reduced fertility, hybrid clones still are capable of producing thousands of germinable seeds which exhibit no deficiencies in establishment or early growth. Thus, no strong barrier was found to prevent the continuous establishment and persistence of backcrosses; gene flow may occur provided suitable disturbed sites are available for colonization.

Aspen: Ecology and management in the western United States

“…Schreiner 1965. Individual reproductive shoots produce 2-10 inflorescences (catkins) each with 50-100 flowers, and 2-10 seeds per flower Winton 1976, Henry andBarnes 1977). The seeds (1-2 millionlkg) are provided with a tuft of dispersal hairs at the basal end, and have an air-dry water content of 6%.…”

Disease biology and histopathology of bronze leaf disease: a threat to cultivated aspens, white poplars and their hybrids

“…Within their range, hybrids between bigtooth ( P. grandidentata ) and trembling ( P. tremuloides ) aspens ( P . × smithii Boivin) are known to be locally common (Barnes, ; Barnes & Pregitzer, ; Henry & Barnes, ), and although bigtooth aspen generally flowers 10–14 days later than trembling aspen, temperature inversions (Pauley, ) and late‐flowering catkins (Einspahr & Joranson, ) can overcome the differences in time of flowering of the two species resulting in natural hybrids. The European white poplar ( P. alba ) was introduced into North America almost entirely as female populations and can readily hybridize with bigtooth and trembling aspen (Barnes, ; McComb & Hansen, ; Spies & Barnes, ).…”

Flowering phenology and seed viability of native and non-native poplars in north-central Alberta

“…When nonnative trees are introduced into novel habitats they can affect the ecosystem by altering native populations through inhibiting germination, establishing new hybrid plants followed by introgression, or reducing growth rates of the native species due to their high susceptibility to disease and pests (Anderson 1949, Henry and Barnes 1977, Engelmark et al 2000, Leege and Murphy 2001.…”