Flora of North America species comparison

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Quercus pacifica

Quercus coccinea

Channel Island scrub oak, island scrub oak, Pacific oak

scarlet oak
Habit Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller. Trees, deciduous, to 30 m; lower trunk without stubs of dead branches.
Bark

scaly on older branches and trunk.

dark gray to dark brown, irregularly fissured with scaly ridges, inner bark orangish pink.
Twigs

brownish or reddish, minutely puberulent, becoming glabrate and gray with age.

reddish brown, (1-)2-3.5 mm diam., glabrous.
Buds

light or chestnut brown, ovate or globose, 2-3 × 1-2 mm.

Leaves

blade obovate or oblong, planar to moderately convex or undulate, 15-40 × 7-20(-40) mm, base cuneate or rounded, attenuate-decurrent along petiole, margins minutely cartilaginous, entire or with 1-5 irregular teeth on each side, secondary veins obscure, 1-5 on each side, apex blunt or rounded, occasionally subacute with mucronate tip;

surfaces abaxially waxy, glandular, with scattered minute, flat, appressed, ± 8-rayed stellate hairs, not obscuring surface, adaxially green, glossy, glabrate or with minute, scattered, stellate hairs.

blade elliptic to ovate or obovate, 70-160 × 80-130 mm, base obtuse to truncate, margins with 5-9 deep lobes and 18-50 awns, lobes distally expanded, sinuses usually extending more than 1/2 distance to midrib, apex acute;

surfaces abaxially glabrous except for minute axillary tufts of tomentum, adaxially glossy light green, glabrous, secondary veins raised on both surfaces.
Acorns

paired or solitary in leaf axil, subsessile, rarely pedunculate in teratological forms;

cup hemispheric to turbinate, to 15 mm deep × 20 mm wide, enclosing only 1/4-1/2 nut, scales moderately to heavily tuberculate, irregularly formed;

nut light brown, acute-cylindric or fusiform, tapered, (15-)20-30 × (6-)9-15 m, apex acute, glabrate.

biennial;

cup turbinate to hemispheric, 7-13 mm high × 16.5-31.5 mm wide, covering 1/3-1/2 nut, outer surface light to dark reddish brown, glossy, glabrous to puberulent, inner surface light brown, glabrous, occasionally with ring of pubescence around scar, scales often tuberculate, base broad, glossy, margins strongly concave with tips tightly appressed, acute to attenuate;

nut oblong to subglobose, 12-22 × 10-21 mm, glabrous, with 1 or more rings of fine pits at apex, scar diam. 6.5-13.5 mm.
Cotyledons

distinct.

Terminal

buds dark reddish brown, conic to ovoid, 4-7 mm, noticeably 5-angled in cross section, usually silvery- or tawny-pubescent distal to middle.
2n

= 24.

Quercus pacifica

Quercus coccinea
Phenology Flowering spring. Flowering spring.
Habitat Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands Poor soils, well-drained uplands, dry slopes, and ridges, occasionally on poorly drained sites
Elevation 0-300 m (0-1000 ft) 0-1500 m (0-4900 ft)
Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DC; DE; GA; IL; IN; KY; MA; MD; ME; MI; MO; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WI; WV
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Quercus pacifica is endemic on three of the California Channel Islands: Santa Cruz, Santa Catalina, and Santa Rosa. It is not known from the mainland, but it bears a superficial similarity to some of the tree forms that are putative hybrids between Q. engelmannii and Q. cornelius-mulleri in San Diego County. The latter populations, sometimes treated as Q. ×acutidens, differ in having much greater variability in leaf shape; thicker, more leathery leaves; denser abaxial leaf vestiture; much smaller hairs, having more than 10 rays; and variable levels of connation of cotyledons (always distinct in Q. pacifica). Quercus pacifica appears to be most closely related to Q. douglasii, whether by direct descent or by introgression with another species no longer extant on the islands.

Quercus ×macdonaldii Greene (as a species) [= Quercus dumosa var. macdonaldii (Greene) Jepson] is a stabilized hybrid complex between Quercus pacifica and Q. lobata Née. The plants tend to be small to moderate trees with leaves that resemble those of Q. lobata; the leaves are much more shallowly lobed and always less than two-thirds the distance from the margin to the midrib. Quercus ×macdonaldii is known from Santa Rosa, Santa Cruz, and Santa Catalina islands.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Trees having acorns with broad, distinctly warty cups are sometimes classified as Quercus coccinea var. tuberculata Sargent.

Quercus coccinea reportedly hybridizes with Q. imbricaria, Q. ilicifolia (= Q. ×robbinsii Trelease), Q. laevis, and Q. palustris (E. J. Palmer 1948) and with Q. phellos, Q. rubra, and Q. velutina (= Q. ×fontana Laughlin).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 3. FNA vol. 3.
Parent taxa Fagaceae > Quercus > sect. Quercus Fagaceae > Quercus > sect. Lobatae
Sibling taxa
Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. coccinea, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Q. acerifolia, Q. agrifolia, Q. ajoensis, Q. alba, Q. arizonica, Q. arkansana, Q. austrina, Q. berberidifolia, Q. bicolor, Q. boyntonii, Q. buckleyi, Q. carmenensis, Q. chapmanii, Q. chihuahuensis, Q. chrysolepis, Q. cornelius-mulleri, Q. depressipes, Q. douglasii, Q. dumosa, Q. durata, Q. ellipsoidalis, Q. emoryi, Q. engelmannii, Q. falcata, Q. fusiformis, Q. gambelii, Q. garryana, Q. geminata, Q. georgiana, Q. graciliformis, Q. gravesii, Q. grisea, Q. havardii, Q. hemisphaerica, Q. hinckleyi, Q. hypoleucoides, Q. ilicifolia, Q. imbricaria, Q. incana, Q. inopina, Q. intricata, Q. john-tuckeri, Q. kelloggii, Q. laceyi, Q. laevis, Q. laurifolia, Q. lobata, Q. lyrata, Q. macrocarpa, Q. margarettae, Q. marilandica, Q. michauxii, Q. minima, Q. mohriana, Q. montana, Q. muehlenbergii, Q. myrtifolia, Q. nigra, Q. oblongifolia, Q. oglethorpensis, Q. pacifica, Q. pagoda, Q. palmeri, Q. palustris, Q. phellos, Q. polymorpha, Q. prinoides, Q. pumila, Q. pungens, Q. robur, Q. robusta, Q. rubra, Q. rugosa, Q. sadleriana, Q. shumardii, Q. similis, Q. sinuata, Q. stellata, Q. tardifolia, Q. texana, Q. tomentella, Q. toumeyi, Q. turbinella, Q. vacciniifolia, Q. vaseyana, Q. velutina, Q. viminea, Q. virginiana, Q. wislizenii
Synonyms Q. dumosa var. polycarpa Q. coccinea var. tuberculata
Name authority Nixon & C. H. Muller: Novon 4: 391. (1994) Münchhausen: Hausvater 5(1): 254. (1770)
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Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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