Key to Quercus

View taxon page for Quercus

(For a list of species in Quercus, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Acorn cup scales thin, not tubercled, shell hairy to woolly inside, at least at tip; bark dark gray or gray-brown to black

2. Leaf moderately to deeply lobed, 

lobes 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

1–4-toothed, teeth generally bristle-tipped; plant deciduous ..... Q. kelloggii

2' Leaf 

entire 

Having margins that are continuous and smooth (i.e., without teeth, lobes, etc.).

to toothed, teeth abruptly pointed to spine-tipped, not bristle-tipped; plant evergreen

3. Leaf generally adaxially convex, margin rolled under or not, obscuring marginal teeth, 

blade 

Expanded portion of a leaf, petal, or other structure, generally flat but sometimes rolled, cylindric, wavy, or cupped.

generally widely 

elliptic 

In the shape of a flattened circle or ellipse; wider than linear

to round; fruit mature in year 1 ..... Q. agrifolia

4. Leaf abaxially glabrous to sparsely hairy except vein axils hair-tufted ..... var. agrifolia

4' Leaf abaxially densely 

tomentose 

Covered with densely interwoven, generally matted hairs.

..... var. oxyadenia

3' Leaf adaxially ± flat, margin not rolled under, blade generally 

lanceolate 

Narrowly elongate, widest in the basal half, often tapered to an acute tip.

to 

oblong 

Longer than wide, with nearly parallel sides; wider than linear.

; fruit mature in years 1–2

5. Leaf abaxially ± yellow or ± white woolly; fruit mature in year 1 ..... Q. ilex

5' Leaf abaxially glabrous; fruit mature in year 2

6. Leaf 2–5 cm, abaxially generally ± shiny, yellow-green; nut distally 

acute 

Having a short-tapered, sharp tip, the sides convex or straight and converging at less than a right angle.

to ± 

obtuse 

Having a short-tapered, blunt tip or base, the sides convex or straight and converging at more than a right angle.

..... Q. wislizeni

7. Shrub 2–4(6) m ..... var. frutescens

7' Tree generally 10–22 m ..... var. wislizeni

6' Leaf 3–9(14) cm, abaxially generally ± dull; nut distally obtuse to ± rounded ..... Q. parvula

8. Tree < 17 m – s NCo, NCoRI, CW (except SCoRI), WTR ..... var. shrevei

8' Shrub 1–6 m

9. Leaf margin generally entire; SCoRO (Santa Barbara Co.), n ChI (Santa Cruz Island), e WTR ..... var. parvula

9' Leaf margin long-tapered 

dentate 

Having margins with sharp, relatively coarse teeth pointing outward, not tipward.

; SnFrB (Mount Tamalpais) ..... var. tamalpaisensis

1' Acorn cup scales generally thick, generally tubercled to ± not, shell glabrous to woolly inside; bark light gray to ± white

10. Acorn nut shell ± woolly inside; fruit mature in year 2; plants evergreen

11. Leaf generally 3–8 cm; acorn cup > 1.5 cm wide; generally tree, > 7 m

12. Leaf adaxially with lateral veins ± not impressed, abaxially golden-puberulent, glabrous in age ..... Q. chrysolepis

12' Leaf adaxially with lateral veins impressed, abaxially densely tomentose, sparsely tomentose in age – ChI ..... Q. tomentella

11' Leaf generally 1–3.5 cm; acorn cup < 1.5 cm wide (if > 1.5 cm wide, leaves <= 3 cm); generally shrub, < 7 m

13. Twigs rigid; 

leaf 

Organ arising from a stem, generally composed of a stalk (petiole) and a flat, expanded, green, photosynthetic area (blade); distinguished from a leaflet by the presence in its axil of a bud, branch, thorn, or flower; sometimes with lateral, basal appendages (stipules); either simple (toothed, lobed, or dissected but not divided into leaflets) or compound (divided into leaflets).

margin wavy, strongly spine-toothed; blade elliptic to round-ovate; plants 2–6 m, 

erect 

Upright; vertically oriented.

..... Q. palmeri

13' Twigs flexible; leaf margin entire to irregularly 

serrate 

Having margins with sharp, fine to coarse teeth generally pointing tipward, not outward; margins with such teeth on such primary teeth are doubly serrate.

, teeth mucronate or spine-tipped; blade oblong or lanceolate to 

ovate 

Egg-shaped (i.e., widest below the middle) in two dimensions (i.e., in one plane), as a leaf.

; plants to 5 m, 

prostrate 

Lying flat on the ground.

to erect

14. Leaf margin entire or with few irregular spine-tipped teeth; dry chaparral, 100–1800 m, sw PR ..... Q. cedrosensis

14' Leaf margin entire to mucro-toothed; montane conifer zone, 900–2800 m, KR, NCoRH, NCoRI, CaRH, SNH, MP ..... Q. vacciniifolia

10' Acorn nut shell glabrous inside; fruit mature in year 1; plants evergreen or not

15. Leaf lobed (± entire, wavy, or ± lobed in Quercus douglasii), margins generally without spines; plants deciduous

16. Leaf abaxially glabrous (in youth sometimes sparsely hairy), base strongly 

cordate 

Heart-shaped; often pertaining to a leaf in which the blade base on both sides of the petiole is rounded and convex.

, often revolute; fr on 

axillary 

Pertaining to or within an axil, especially a leaf axil.

 

peduncle 

Stalk of an individual flower borne singly, not in an inflorescence, or of an entire inflorescence, or the corresponding structure in fruit; the stalk subtending an involucre (e.g., in Asteraceae, Polygonaceae).

(25-)35–65(-100) mm ..... [Q. robur]

16' Leaf abaxially fine-hairy, 

puberulent 

Minutely hairy.

, fine-tomentose, short-hairy, or densely appressed-stellate-hairy, base wedge-shaped, rounded-gradually 

tapered 

Gradually (not abruptly) narrower or smaller at base or tip.

, or 

truncate 

Abruptly (not gradually) narrower or smaller at base or tip, as if cut straight across or nearly so.

(subcordate); fr subsessile or rarely on axillary peduncle to 10(-20) mm

17. Leaf shallowly lobed (sinuses generally < 1/2 distance 

lobe 

1. A major expansion or bulge, such as on the margin of a leaf, sepal, or petal, or on the surface of an ovary. 2. The free tips of otherwise fused structures, such as sepals or petals; larger than teeth.

tip to midrib), adaxially generally dull, green to blue-green

18. Leaf adaxially green; acorn cup scales tubercled; ChI ..... Q. ×macdonaldii

18' Leaf adaxially blue- or gray-green; acorn cup scales ± tubercled; mainland

19. Shrub, tree < 3 m, evergreen to deciduous; leaves 1.5–5 cm, generally irregularly coarsely toothed, adaxially blue- or gray-green ..... Q. ×alvordiana (2)

19' Tree, deciduous; leaves 3–6(8) cm, ± entire, wavy, or ± lobed, adaxially blue-green ..... Q. douglasii

17' Leaf moderately to deeply lobed (sinuses generally > 1/2 distance lobe tip to midrib), adaxially ± shiny, dark green

20. Tree; acorn cup 10–30 mm deep, all scales tubercled; nut 30–50 mm, generally long-conic, distally acute to ± obtuse ..... Q. lobata

20' Shrub to tree; acorn cup 4–9 mm deep, proximal scales ± tubercled, distal ± not; nut 20–30 mm, ovoid to ± spheric, distally rounded ..... Q. garryana

21. Tree 8–20 m, generally with 1 trunk; terminal 

buds 

1. An incompletely developed, more or less embryonic shoot, usually covered with bud scales. 2. An unopened flower, often protected by sepals.

5–12 mm, 

fusiform 

Elongate, widest at the middle, tapered to both ends.

, hairs dense, ± yellow or ± white ..... var. garryana

21' Shrub to small tree 0.3–5 m, generally with > 1 trunk; terminal buds 2–5 mm, hairs sparse, brown or ± red

22. Rays of 

stellate 

Pertaining to a hair or other structure with three or more branches radiating in two or three dimensions from a common point.

hairs on leaf abaxially generally 4–6, 0.25–0.5 mm; KR, NCoRH, CCo ..... var. breweri

22' Rays of stellate hairs on leaf abaxially generally 6–8, < 0.3 mm; KR, NCoRI, CaR, SN, SnFrB, SCoRO, ne WTR, MP ..... var. semota

15' Leaf generally entire to toothed, not lobed, teeth with spines or not; plants generally evergreen

23. Leaves 7–11(18) cm, serrate, lateral veins of larger leaves generally 20–28, generally straight and prominent; stipules persistent, > 10 mm, silky-hairy ..... Q. sadleriana

23' Leaves 1–6 cm, entire to dentate, lateral veins of larger leaves generally < 20, generally not straight and prominent; stipules early-deciduous, < 10 mm, not silky-hairy

24. Shrub to tree generally > 5 m; leaves 2–6 cm, oblong to obovate, entire or ± toothed, adaxially shiny green to dull blue-green

25. Shrub, small tree 5–6(10) m; leaf blade (10)20–35(60) mm, adaxially shiny green to dull blue-green, margin entire, dentate, or wavy-dentate ..... Q. ×acutidens (2)

25' Tree 5–25 m; leaf blade (20)30–60(80) mm, adaxially blue-green, dull, margin wavy-dentate to generally entire ..... Q. engelmannii

24' Shrub to small tree generally < 5 m (Quercus berberidifolia sometimes a small tree to 8+ m); leaves 1–5 cm, elliptic to ovate or ± round, variously toothed, adaxially shiny to dull green to dull blue-, yellow-, or gray-green

26. Leaf 2-colored, adaxially yellow- to gray-green, abaxially ± white, densely fine-tomentose, hairs obscuring lateral veins ..... Q. cornelius-mulleri

26' Leaf 1–2-colored, adaxially green to gray- or blue-green, abaxially dull light or pale green or gray-green, not densely tomentose, hairs not obscuring lateral veins

27. Leaf generally oblong to obovate, margin wavy to obtuse-toothed; PR ..... Q. ×acutidens (2)

27' Leaf elliptic to ovate or ± round, margin toothed, teeth abruptly pointed to spine-tipped

28. Acorn cup thin, scales ± tubercled to not; leaf adaxially gray- or blue-green, dull

29. Acorn stalk 10–15 mm, nut cylindric-ovoid to elliptic, 12–23 mm, generally yellow-brown, distally obtuse; leaves oblong to elliptic, generally regularly spine-toothed ..... Q. turbinella

29' Acorn stalk 0, nut conic-ovoid, 20–40 mm, generally dark brown, distally acute to ± obtuse; leaves oblong to elliptic or obovate, irregularly toothed, teeth blunt to weakly spiny

30. Shrub to small tree < 3 m; leaves 1.5–5 cm, toothed but not spine-toothed, adaxially blue- to gray-green ..... Q. ×alvordiana (2)

30' Shrub 2–5 m to tree < 7 m; leaves 1.3–2.8 cm, spine-toothed, adaxially gray-green ..... Q. john-tuckeri

28' Acorn cup thick, scales tubercled; leaf adaxially generally green, ± shiny (dull or not in Quercus durata)

31. Leaf adaxially dull, convex, margin often rolled under, obscuring teeth ..... Q. durata

32. Leaf adaxially strongly convex, abaxially short-hairy when young; generally on serpentine, NCoR, n SN, s CCo, SnFrB, SCoR ..... var. durata

32' Leaf adaxially ± convex, abaxially densely short-hairy when young; not on serpentine, se WTR, SnGb (s slope) ..... var. gabrielensis

31' Leaf adaxially ± shiny, flat to ± wavy, not convex, margin generally not rolled under

33. Leaf abaxially with 

spreading 

Oriented more or less perpendicularly to the axis of attachment; often, more or less horizontal.

, 2–6-rayed hairs – SCo, PR, chaparral or coastal-sage scrub, < 200 m ..... Q. dumosa

33' Leaf abaxially with 

appressed 

Parallel or nearly parallel to and often in contact with surface of origin; used to describe the disposition of hairs, leaves, pedicels, etc.

, 4–10-rayed hairs

34. Leaf base wedge-shaped or generally truncate or rounded; margin mucro- or spine-toothed; widespread on mainland ..... Q. berberidifolia

34' Leaf base gradually tapered, wedge-shaped, or rounded; margin entire, wavy, or ± toothed, teeth generally mucronate; ChI ..... Q. pacifica

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