The genus Quercus (the oaks) is notorious for interspecific hybrization, generating questions about the mechanisms that permit coexistence of closely related species. Two sister oak species, Quercus virginiana and Q. geminata, occur in sympatry in Florida and throughout the southeastern United States. In 11 sites from northern and southeastern regions of Florida, we used a leaf-based morphologi...

The genus Castanea (Fagaceae) is widely distributed in the deciduous forests of the Northern Hemisphere. The striking similarity between the floras of eastern Asia and those of eastern North America and the difference in chestnut blight resistance among species has been of interest to botanists for a century. To infer the biogeographical history of the genus, the phylogeny of Castanea was estim...

Pollen morphology of three parental Quercus species (Q. robur L., Q. petraea (Matt) Liebl, Q. pubescens Willd.) and two spontaneous hybrids of these species (Q. ×calvescens Vuk. = Q. petraea × Q. pubescens and Q. ×rosacea Bechst. = Q. robur × Q. petraea) was investigated in this study. The pollen originated from 18 natural oak sites and 67 individuals (oak trees). Each individual was represente...

Environmental and leaf trait effects on herbivory are supposed to vary among different feeding guilds. Herbivores also show variability in their preferences for plant ontogenetic stages. Along the vertical forest gradient, environmental conditions change, and trees represent juvenile and adult individuals in the understorey and canopy, respectively. This study was conducted in ten forests sites...

We report on growth and survivorship of two cohorts of blue oaks Quercus douglasii Hook. & Arn. (Fagaceae) monitored at Hastings Reservation in Monterey County, California, the first growing in an unprotected old field and measured as seedlings in 1965 and the second planted as acorns in 1985 in several sites differing in their degree of protection from grazing. Growth of all individuals was ex...

In a greenhouse experiment, seedling survival of two oak species (Quercus rugosa and Q. laurina) was greatly affected by the excision of cotyledons 1 mo after germination, with a greater impact on Q. laurina. The effect of seed size was also significant for both species, with a positive correlation between seed mass and survival and growth. The effect of cotyledon excision on seedling growth pe...