Fecund and promiscuous
Natural hybridisation is a hallmark of the Quercus genus: oaks of different species cross like mad. It's not a total free-for-all (oaks of distantly related types are unlikely to cross) but it happens to a remarkable extent. Further complicating matters, species like the English oak (Q. robur) show tremendous diversity in their appearance.
It makes for a big fat challenge for Oaks New Zealand. They're on a quest to identify the best parent trees and to improve the genetic diversity in trees they're selecting for forestry. The best seed sources are from a pure stand of trees, relatively isolated from other species.
But most of the best oaks in New Zealand (and virtually all the rare ones) are in arboreta, created by collectors who wanted one of everything and planted them next door to each other.
In practice, the group relies on Eric and Kathryn's botanical skills to identify trees and their acorns, propagating them, and then weeding out seedlings that vary from the phenotype.
However, that all goes out the window with the Mexican oaks. Mexico is the epicentre of Quercus diversity, with 160 species native to the region. Many are used for timber, but not in a systematic way and they're not grown in plantations either.
Eric is backing the Mexican oak as a potential forestry tree for NZ and is looking to exploit the ‘hybrid vigour' associated with first-generation crosses. He's collecting acorns from the most mixed stands of Mexican species he can find and planting out the best-looking, fastestgrowing
■ of the progeny. Watch this space.