Oaks - 11/1994

FRIENDS OF EDGEWOOD NATURAL PRESERVE

[ Home ] [ Up ] [ Link to FoE ] [ Contents ] [ Search ]

[ Annual Meeting ] [ Signs ] [ Weed Eradicators ] [ Bylaws Available ] [ President's Message ] [ Oaks ] [ Re-Veg the Edge ] [ Docent Training ] [ What's in a Name? ] [ Master Plan Update ] [ Miscellany ] [ Upcoming Events ]

AN OAK, BY ANY OTHER NAME, IS A QUERCUS

By Susan Sommers

Part	Black Oaks	White Oaks
Bark	Dark with irregular breaks in mature trees	Light color with furrows in mature trees
Leaf	Underside undistinguished green	Underside dull or pale
Acorn cup	Thin, overlapping scales	Thickened, knoblike scales
Acorn	Woolly inside, mature in two years for most species	Smooth inside, mature in one year

The question is which one am I seeing? Among the 300 species of oaks, many will cross-breed (hybridize). The revelation of their mysterious identities requires a bit of the Sherlock Holmes sleuthing technique: a sharp eye, and the practical use of some clues. Some trees may be more difficult because of hybridization especially in regions where species overlap in their range. The main clues are the specimen’s location (within what range); its bark, leaf, flower, fruit (acorn), and in some instances the type of soil on which it grows. In all oaks, the flowers are in catkins (clusters of flowers without petals). The males are rather showy and near the tip of the branches, while the much less obvious females are located farther in on the branches.

Part	Deciduous		Evergreen
	Valley	Blue	Scrub	Leather
Hybridization	With Blue and Scrub	With Valley and Scrub	With Valley and Blue	N/A
Plant form	Tree	Tree	Shrub, can be tree-like	Shrub
Leaf	Deeply lobed	Lobed, not deeply	Shining	Dull
	Not blue	Blue-green	Few hairs on top	Hairs on top starlike
	No bristles	No bristles	Bristles somewhat curved	Bristles very rolled under
Cup	Deeply hemispheric	Shallow	Thick walls, somewhat knobby scales	Thick walls, very knobby scales
Acorn	Long, tapered	Oval, acute tip	Long, tapered	Ovoid, acute tip
Soil	Varied	Varied	Varied	Serpentine

There are primarily two groups of oaks growing at Edgewood: black and white. Within each group are species that either lose all their leaves (deciduous) and species that retain some of their leaves all year (evergreen). The black oaks will hybridize amongst themselves although not readily. The white oaks will hybridize readily amongst their deciduous and evergreen types as well as between the deciduous and evergreens. Hybrids will have some of their parents’ characteristics and tend to be sterile.

At Edgewood the black evergreen oak representative is the Coast Live Oak (Quercus agrifolia). The white oak deciduous species includes the Valley or Roble Oak (Q. lobata), and the Blue Oak (Q. douglasii). The evergreen white oaks are represented by the Scrub Oak (Q. dumosa) and the Leather Oak (Q. durata).


Valley Oak, drawn by Celeste Kirsher

Send mail to wm at this domain with questions or comments about this web site. Copyright © 1999 - 2008 Friends of Edgewood Natural Preserve. Last modified: January 20, 2008.