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Oak Galls: A Strange Biology Indeed!, W. John Hayden
Oak Galls: A Strange Biology Indeed!, W. John Hayden
Biology Faculty Publications
Anyone who takes the time to look closely at several branches of oak will soon find one or another peculiar anomaly among the leaves and twigs. One can easily find structures resembling Ping-Pong balls, hard knots, fluffy tufts, horns—either single or clustered, or irregular thickenings, to mention just a few possibilities. These abnormal growths are galls, structures caused by the presence of small insect larvae living inside the tissue of the plant. Galls can be found on a wide variety of plants. They are common, for example, on the stems of goldenrods, and the leaves of maples, but oaks are …
White Oak Part Of Global Oak Presence, W. John Hayden
White Oak Part Of Global Oak Presence, W. John Hayden
Biology Faculty Publications
As we act locally celebrating white oak, Quercus alba, as the 2011 VNPS Wildflower of the Year, it is perhaps appropriate to think globally for a few moments and consider the breadth of diversity encompassed by the oaks. Quercus is a big genus, easily the largest in its family, the Fagaceae. Approximately 400 species of oak are known, and they are widely distributed in the northern hemisphere. We tend to think of oaks as temperate zone trees, but in the New World, their range extends south through the mountains of Central America to Colombia and in the Old World, …
Hybrid Oaks: Full Of Vexation And Wonder, W. John Hayden
Hybrid Oaks: Full Of Vexation And Wonder, W. John Hayden
Biology Faculty Publications
Distinguishing different species of oak in the forests of eastern North America can be challenging. For one thing, there are simply a lot of different species to sort out. A recent reference (Stein et al. 2003), describes 50 species in the genus Quercusoccurring naturally east of the 100th meridian, and 90 species are distinguished for all of North America north of Mexico (Nixon 1997). With so many species to parse, confident identification requires careful study of leaves, stem and leaf hairiness, and fully mature acorns with their caps. But care is not always enough, because in addition to the …
2011 Wildflower Of The Year: White Oak, Quercus Alba, W. John Hayden
2011 Wildflower Of The Year: White Oak, Quercus Alba, W. John Hayden
Biology Faculty Publications
Emblematic of strength and longevity, white oaks grace the deciduous forests of eastern North America.