Birds song and pollen in the air these days, and many folks wonder “what are these caterpillar-like things all over the ground?”  Some of those are spent oak catkins (other trees  such as birch and willow produce catkins too). Other fun oak facts & folklore.

Oaks are monoecious – a single oak tree produces both male flowers (in the form of “catkins”) hanging down to allow wind to take their pollen to any receptive female flowers  on another branch of the same tree, or any oak flower in the vicinity. Female flowers are harder to spot and appear (where you would expect a bud to be) as a fuzzy three-lobed stigma with an egg shaped ovary beneath. Thanks to Bob Klips for posting this great image of a female oak flower.


Though oaks  (the flowering plant genus Quercus) include some of America’s most ecologically and economically important trees (approximately 255 “new world” lineage – of an estimates over 600 worldwide) and provide significant ecosystem services (woody plant biomass, biodiversity, ecology and nutrient cycling), the biodiversity of this genus is poorly understood. Andrew Hipp, Senior Scientist at the Morton Arboretum studies the basic question of how oak traits, distributions, and diversity evolve in response to changes in habitat and climate. For more information about his “quercky” work –  see the Morton Arboretum Lab site.

PastedGraphic-2 female oak flowers

male oak flowers (catkins)


May everyone have an awesome and allergy free spring experience!