
Fagaceae (fag-AY-see-ee)
Iconic Features
- Shrubs or trees
- Leaves simple and alternate
- Male flowers in catkins
- Fruit an acorn or spiny-burred nut
Description (Jepson)
- Eudicotyledons (eudicots) – a major lineage of flowering plants including most plants traditionally described as dicots and generally characterized by
- 2 seed leaves (dicotyledon)
- Netted (reticulate) leaf venation
- Flower parts in fours and fives
- Pollen grains with 3 pores (tricolpate)
- Vascular bundles in stem arranged in a ring
- Taproot system
- Deciduous or evergreen shrubs and trees
- Leaves
- Simple (not divided into leaflets); entire (with smooth margins) or lobed
- Alternate (1 leaf at each junction with stem)
- Flowers
- Separate male and female flowers on same plant (monoecious)
- Male flowers
- Female flowers
- Inconspicuous, growing at leaf junctions of new branches or below catkins
- Ovary inferior (below the attachment of other flower parts)
- Fruit is a nut, partly enclosed by a scaly or warty cup (acorn); or 1-3 nuts, enclosed by spiny burs
Adaptations
- Oaks are masting species (Koenig and Knops 2005; Golden Gate 2012)
- Most years, oaks produce few or no acorns, instead conserving energy for growth
- About every 5 years, oaks put tremendous energy into producing an abundant crop, called a masting
- Increased acorn production in mast years ensures that more acorns escape predation, as the predator population cannot consume the amount of available food
- Masting produces a “trophic cascade,” affecting the number of organisms in the entire local food chain, with ripple effects that last years
- For example, populations of mammals who feast on acorns increase, thereby hosting more ticks, resulting in a potential increase of Lyme disease
- Oaks of different species synchronize masting cycles
- Scientists have not yet determined what triggers a mast year or how species synchronize masting across large areas, but temperature fluctuations may be a cue and thus may be affected by climate change
- The term mast comes from an Old English word for woodland nuts that gathered on the ground and were used to feed livestock, such as pigs

Notes
- Approximately 900 species, generally in the northern hemisphere
- Includes oaks, chinquapins, beeches, and chestnuts
- “Oak woodlands are one of the richest broad habitats in the state with well over 300 terrestrial vertebrates utilizing woodlands at some time during the year” (Standiford 2019)
- Oaks (Quercus) and beeches (Fagus) are wind pollinated
- About 12% of flowering plants and most conifers are wind-pollinated (US Forest Service)
- These plants do not waste energy on flower features that attract animal pollinators; instead, their flowers generally have these characteristics
- Small, petalless, and unscented, with muted colors
- No nectar
- Stamen (male flower part) and stigma (pollen-receiving part of the pistil/female structure) are exposed to air currents
- Male flowers produce a great deal of pollen, which is very small, dry, and easily airborne, as all allergy sufferers know!
- Chestnuts (Castenea species) and chinquapins (Castanopsis species), unlike oaks are pollinated by insects (Singh 2019)
- Flowers produce strong odors to attract pollinators
- Scientific name from the included genus Fagus, from the Latin for “beech”
- Represented by 5 native and 1 non-native oak species at Edgewood, as well as many hybrids
- Coast live oak (Q. agrifolia var. agrifolia) is in the red oak lineage (Section Lobatae), commonly called the red oak group
- All other native oaks at Edgewood – leather (Q. durata var. durata), valley (Q. lobata), scrub (Q. berberidifolia), and blue (Q. douglasii) – are in the white oak evolutionary lineage (Section Quercus), commonly called the white oak group
- A single non-native cork oak (Q. suber; Section Serris) grows at the Day Camp
- Oaks in the same lineage may hybridize; in fact, in the Bay area they often do
- Four of Edgewood’s five native oak species can be found near the junction of the Serpentine and Sylvan trails
- Valley (Q. lobata), blue (Q. douglasii), and coast live oaks (Q. agrifolia var. agrifolia) grow close together trailside on the upper Sylvan trail
- Look for the young blue oak that grows downhill and to the left of an unusual blue-leather hybrid
- Leather oaks grow trailside on the Serpentine trail near the junction with the Sylvan
Specific References
Golden Gate National Parks Conservancy. 2012, Dec. 29. Critical Mast: The Boom and Bust of Acorns.
Koenig, W.D. and Knops, J.M.H. 2005. The mystery of masting in trees: some trees reproduce synchronously over large areas, with widespread ecological effects, but how and why? American Scientist, 93(4), 340-347.
Nixon, Kevin C. 2002. The oak (Quercus) biodiversity of California and adjacent regions. In: Standiford, Richard B., et al, tech. editor. Proceedings of the Fifth Symposium on Oak Woodlands: Oaks in California”s Challenging Landscape. Gen. Tech. Rep. PSW-GTR-184, Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture: 3-20.
Singh, G. 2019. Plant Systematics: An Integrated Approach, Fourth Edition. CRC Press.
Standiford, R.B. 2019. University of California Oak Woodland Management.
Browse Some Edgewood Plants in this Family



