Jepson Herbarium
The University and Jepson Herbaria
University of California, Berkeley
Jepson eFlora: Taxon page
Vascular Plants of California
Key to families | Table of families and genera
Previous taxon Index to accepted names and synonyms:
| A | B | C | D | E | F | G | H | I | J | K | L | M |
| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Next taxon

Quercus douglasii

BLUE OAK


Higher Taxonomy
Family: FagaceaeView DescriptionDichotomous Key
Common Name: OAK FAMILY
Habit: Shrub, tree, evergreen or not; monoecious. Leaf: simple, alternate, petioled; margin entire to lobed; stipules small, generally deciduous. Staminate Inflorescence: catkin or stiff spike, many-flowered. Pistillate Inflorescence: 1--few-flowered, generally above staminate inflorescence; involucre bracts many, generally overlapping, flat or cylindric. Staminate Flower: calyx generally 4--6-lobed, minute; petals 0; stamens 4--12+. Pistillate Flower: calyx generally 6-lobed, minute; petals 0; ovary inferior, style branches generally 3. Fruit: 1 nut subtended, partly enclosed by scaly, cup-like involucre or 1--3 nuts subtended, enclosed by spiny, bur-like involucre; mature years 1--2. Seed: generally 1.
Genera In Family: 7 genera, +- 900 species: generally northern hemisphere. Note: Wood of Quercus critical for pre-20th century ship-building, charcoal for metallurgy; some now supply wood (Fagus, Quercus), cork (Quercus suber), food (Castanea, chestnut). Lithocarpus densiflorus moved to Notholithocarpus.
eFlora Treatment Author: John M. Tucker, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: QuercusView DescriptionDichotomous Key


Common Name: OAK
Habit: Evergreen or not. Leaf: stipules small, generally early-deciduous. Staminate Inflorescence: catkins, 1--several, pendent, slender, proximal on twig. Pistillate Inflorescence: in distal leaf axils, short-stalked; flower generally 1. Staminate Flower: stamens 4--10. Pistillate Flower: calyx minute, generally 6-lobed; ovary enclosed by involucre. Fruit: nut 1, partly enclosed by cup-like involucre (cup) with appressed scales (nut and cup = acorn), remnants of perianth and style persistent as small point at tip; scales tubercled to not; mature in years 1 (on younger stems) or 2 (on older stems). Chromosomes: 2n=24.
Etymology: (Latin: ancient name for oak) Note: Many named hybrids; those (3) treated here form widespread populations; most others occur as single individuals, and some but not all of these are mentioned here, under the first parent treated (alphabetically). Reproduction of many species declining due to habitat degradation or loss as well as disease. Quercus robur added, as waif.
eFlora Treatment Author: Thomas J. Rosatti & John M. Tucker
Reference: Manos et al. 1999 Molec Phylogen Evol 12:333--349
Unabridged Reference: Cottam, W. P., J. M. Tucker, & F. S. Santamour. 1982. Oak hybridization at the University of Utah. State Arboretum of Utah Publication No. 1. Salt Lake City; Hardin, J. W. 1975. Hybridization and introgression in Quercus alba. Journal of the Arnold Arboretum 56: 336--363; Manos, P. S., Doyle, J. J., & Nixon, K. C. 1999. Phylogeny, biogeography, and processes of molecular differentiation of Quercus subgenus Quercus (Fagaceae). Molec Phylogen Evol 12: 333--349.
Quercus douglasii Hook. & Arn.
NATIVE
Habit: Tree 6--20 m, deciduous; trunk bark checkered into thin scales, +- gray. Leaf: 3--6(8) cm; petiole 3--9 mm; blade oblong to obovate, adaxially dull, blue-green, abaxially puberulent, pale blue-green, tip generally rounded, margin +- entire, wavy, or +- lobed. Fruit: cup 12--20 mm wide, 6--10 mm deep, cup- to bowl-shaped, scales +- tubercled; nut 20--35 mm, ovoid to subcylindric, distally acute to +- obtuse, shell glabrous inside; mature in year 1.
Ecology: Dry slopes, interior foothills, woodland; Elevation: < 1590 m. Bioregional Distribution: KR, NCoRO, NCoRI, CaRF, SNF, Teh, ScV (Sutter Buttes), SnJV, SnFrB, SCoR, s ChI (Santa Catalina Island), WTR (n slope), MP. Flowering Time: Apr--May Note: Hybridizes with Quercus garryana (Quercus ×eplingii C.H. Mull.), Quercus john-tuckeri (Quercus ×alvordiana), Quercus lobata (Quercus ×jolonensis Sarg.).
Jepson eFlora Author: Thomas J. Rosatti & John M. Tucker
Reference: Manos et al. 1999 Molec Phylogen Evol 12:333--349
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

Previous taxon: Quercus cornelius-mulleri
Next taxon: Quercus dumosa

Botanical illustration including Quercus douglasiibotanical illustration including Quercus douglasii


Please use this Google Form for Contact/Feedback

Citation for this treatment: Thomas J. Rosatti & John M. Tucker 2014, Quercus douglasii, in Jepson Flora Project (eds.) Jepson eFlora, Revision 2, https://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=40581, accessed on December 03, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora, https://ucjeps.berkeley.edu/eflora/, accessed on December 03, 2024.

Quercus douglasii x
click for image enlargement
©2017 Neal Kramer
Quercus douglasii
click for image enlargement
©2020 Neal Kramer
Quercus douglasii
click for image enlargement
©2007 Neal Kramer
Quercus douglasii
click for image enlargement
©2015 Keir Morse
Quercus douglasii
click for image enlargement
©2008 Keir Morse

More photos of Quercus douglasii
in CalPhotos



Geographic subdivisions for Quercus douglasii:
KR, NCoRO, NCoRI, CaRF, SNF, Teh, ScV (Sutter Buttes), SnJV, SnFrB, SCoR, s ChI (Santa Catalina Island), WTR (n slope), MP.
MAP CONTROLS
1. You can change the display of the base map layer control box in the upper right-hand corner.
2. County and Jepson Region polygons can be turned off and on using the check boxes.
map of distribution 1

(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurrence).






 

Data provided by the participants of the  Consortium of California Herbaria.

MAP LEGEND
View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
READ ABOUT YELLOW FLAGS

CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).