Nomenclature

Quercus alba L., Sp. Pl. 2: 996. 1753. Quercus alba f. typica Trel., Mem. Nat. Acad. Sci. 20: 103, t. 172, fig. 1. 1924.

Description

HABIT Perennial, deciduous (occasionally marcescent), phanerophytic, tree, diclinous and monoecious, 25-30 m tall.

STEMS Main stems ascending or erect, round. Bark light gray to dark gray, quite variable in texture from scaly to flaky on younger specimens from ridged to blocky on older specimens, many trees often displaying two or more characteristics for different sides of the tree, see Baranski, 1975. Branches erect or ascending or horizontal. Twigs dark red-brown to dark brown or brown or gray, fluted-terete, 2-5 mm in diameter, smooth and lenticellate, glabrous, (occasionally 1st year twigs glaucous, occasionally 1st year twigs with some fasciculate hairs). Pith white, 5-pointed, continuous, nodal diaphragm absent. Sap translucent. For an anatomical study of the xylem see Tillson & Muller, 1942;Williams, 1939. For an anatomical study of seedling roots see Carpenter & Guard, 1954. For a micro-morphological study of the root/mycorrhizae interface see Jackson & Driver, 1969.

BUDS Terminal and axillary present, clustered at twig apices and scattered along stem, sessile. Terminal bud ovoid to subglobose, blunt; axillary buds ovoid to subglobose, blunt. Bud scales brown to orange-brown, imbricate, with short and unbranched appressed brown hairs, sparsely or moderately densely distributed apically and marginally. Bud scale scars encircling the stem. Leaf scars half round to crescent-shaped. Vascular bundle scars numerous and scattered.

LEAVES Simple, alternate, (appearing pseudo-opposite or pseudo-whorled at twig apices), crowded toward stem apex or spaced somewhat evenly along and divergent from stem. Stipules lateral, free from the petiole, linear, caducous. Petiole adaxially flattened, 0.3-2 cm long, glabrous (occasionally with some fasciculate hairs). For a micro-anatomical overview of the petiole abscission region see Berkeley, 1931. Leaf blades: abaxial surface light green (rarely glaucous), adaxial surface green, narrowly elliptic or oblanceolate or obovate, bilaterally symmetric, 7-22 cm long, 3.5-13 cm wide, chartaceous, pinnately veined; base cuneate or occasionally acute; margin lobed, cleft to parted 1/3 to almost full distance to the midvein; lobe apices obtuse, lacking bristle tips. Variations in lobing have been investigated (Britton, 1881);(Hardin, 1975);(Baranski, 1975) and infraspecific names assigned (Q. alba var. latiloba Sarg. (Sargent, 1918), Q. alba var. pinnatifida Michx. (Michaux, 1801), et al.). Some of these purported infraspecific taxa may perhaps be attributed to hybridization or environmental/physiological influences such as vigorous sports, a second flush of leaves in the same season due to defoliation by drought or herbivory, leaf position in the canopy with regard to solar aspect, etc. Abaxial surface papillose, essentially glabrous or with tufts of white to light brown simple hairs in vein axils (also minute white-light brown (reddish?) simple or fasciculate hairs scattered throughout, 20+ x magnification needed). Adaxial surface glabrous. Other types of hairs (multi-cellular bulbous, fasciculate-tomentose) present on immature leaves only, see Hardin, 1979a;Thompson & Mohlenbrock, 1979; and for an overview of the phenology and the variability and density of hairs due to ecological factors and hybridization see Hardin, 1979b.

FEMALE INFLORESCENCES Coetaneous, spike consisting of a single flower (sometimes 2-3), in axils of current year leaves, subsessile initially, often becoming pedunculate in fruit, surrounded by a cupule which is persistent, accrescent, and indurate in fruit (acorn cap). There has been debate over the years regarding the true ontogenetic nature of the cupule. Originally thought to be an involucre of bracts, recent research suggests that the cupule is a complex partial inflorescence derived from stem tissue, see Abbe, 1974;Brett, 1964;Foreman, 1966;MacDonald, 1979;Fey & Endress, 1983. Each cupule subtended by 3 minute, caducous bracteoles.

FEMALE FLOWERS Perianth of one whorl, minute, fragrance absent. Calyx urceolate, of fused sepals. Carpels 3. Locules 3, each containing 2 ovules. Styles 3, each with 1 stigma. Ovary inferior. Placentation axile. For an investigation of embryogenesis see Stairs, 1964. For an ontogenetic study see Rebuck, 1952.

MALE INFLORESCENCES Coetaneous, compound, solitary or fascicled spikes; pendant, catkin-like; in leaf axils of previous year. Rachis moderately covered with brown hairs, elongating and glabrescent with age, with 1-3 sessile flowers per node, each flower subtended by a small, sessile caducous bracteole.

MALE FLOWERS Perianth of one whorl, 2-3 mm in diameter, fragrance absent. Calyx actinomorphic, campanulate, of fused sepals. Sepal lobes 5-6, broadly oval to ovate with brown pilosity, moderately dense to densely distributed throughout. Stamens (2)6-9(16), exserted, surrounding tuft of brown hairs. Anthers glabrous, basifixed, opening along the long axis. Filaments free, 1mm long, straight, glabrous(Rowlee & Nichols, 1900). For a review of pollen morphology see Solomon, 1983b. For an investigation of microsporogenesis see Stairs, 1964.

FRUITS Acorn (glans (Spjut, 1994)) (calybium (Kaul, 1985)) subsessile or pedunculate to 3 cm; maturation annual. Acorn ovoid-oblong, 1.2-2.5 cm long, comprised of 2 parts- a. the crateriform cup (cupule), enclosing 1/4 to 1/3 (rarely 1/2?) of the base of the nut; and b. the nut, 1-seeded by abortion (rarely 2-3 seeded (Britton, 1886)(Harvey, 1917)(Smith, 1914)). For a hypothesis that the first ovule fertilized suppresses the normal development of the others see Mogensen, 1975. Cupule exterior composed of indurate, imbricate, tuberculate, tightly appressed scales moderately to densely covered with brown to grey tomentum. Nut olive-green to brown, ovoid-oblong, with large light-colored circular cupule scar at base and apiculate at the distal end, essentially smooth (minutely laterally striate), glabrous except for minute brown tomentum on apiculus. One study found a size range of .4-5.86 cubic cm with a mean of 2.02 cubic cm and a correlation between smaller acorn size with increasing latitude (Aizen & Woodcock, 1992). Reported to be rarely viviparous (Andresen, 1955).

SEEDS Embryo with two large fleshy cotyledons, endosperm lacking. (Young & Young, 1992).

Habitat

Usually mesic to dry (rarely wet) woods, slopes, and barrens.

Distribution

Indigenous to eastern North America.

United States -- AL, AR, CT, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, NE, NH, NJ, NY, OH, OK, PA, RI, SC, TN, TX, VA, VT, WI, WV

Canada -- ON, QC

New York Metropolitan Region -- Native throughout the metropolitan region.

Rarity Status

Global Heritage Rank -- G5

Connecticut -- Not listed

New Jersey -- Not listed

New York -- Not listed

Species Biology

Flowering

April [week 4] - May [week 4] (June [week 3])

Pollination

Anemophily

Fruiting

August [week 1] - October [week 3] (Farmer, 1981) (Conner, et al., 1976) Often masting, for an investigation on the effects of weather on acorn yields see Sharp & Sprague, 1967. For a study suggesting that masting is effected by weather in conjunction with inherent reproductive cycles see Sork, et al., 1993. 

Dispersal

Small predators of acorns facilitate dispersal by dropping undamaged nuts and failing to recover cached nuts. These include Sciurus carolinensis (gray squirrel), Sciurus niger (fox squirrel), Glaucomys volans (Southern Flying Squirrel), Tamias striatus (eastern chipmunk), Peromyscus leucopus (white-footed mouse), Peromyscus maniculatus (deer mouse) and Quiscalus quiscula (common grackle) and Cyanocita cristata (blue jay). (Ivan & Swihart, 2000) (Smith, 1972) (Briggs & Smith, 1989) (Wolff, 1996) (Bosema, 1979) (Darley-Hill & Johnson, 1981) (Johnson & Webb, 1989) (Johnson, et al., 1993) (Vaughan, 1991).

In addition, one study found that many predators preferred the basal end of the acorn and consumed only 30-60% of the cotyledon. A chemical analyses of acorns from two species revealed that the concentration of protein-precipitable phenolics (primarily tannins) was 12.5% (Q. phellos) and 84.2% (Q. laevis) higher in the apical portion of the seeds where the embryo is located, suggesting that many acorn consumers consistently eat only a portion of the cotyledon of several species of acorns and thereby permit embryo survival. (Steele, et al., 1993). Probably included in the diet of the grey fox (Urocyon cinereoargenteus) (Scott, 1955), eastern wild turkeys (Meleagris gallopavo silvestris) (Norman, 2003), and white-tailed deer (Odocoileus virginianus) (Bryant, et al., 1996).

Germination

(Rink & Williams, 1984) (Barnett, 1977) One study of fall-planted acorns in experimental seedbeds found germination rates of 50-100% across different US provenances (Santamour & Schreiner, 1961).

General rules for collecting and storing acorns: 1. Collect acorns before they lose much water. 2. Ensure acorns are fully hydrated, soak in clean tap water overnight before placing them in storage. 3. Surface dry the acorns just before depositing them in storage to reduce mold growth. 4. Place acorns into cold storage as soon after collection as is possible. (Connor, 2004)

In one study (Q. phellos and Q. laevis), germination experiments revealed equal or greater germination frequencies for partially consumed acorns than for intact acorns. (Steele, et al., 1993).

Quercus alba hybrids in the NYMF area

Quercus x saulii Schneid. (alba x montana)

Quercus x jackiana Schneid. (alba x bicolor)

Quercus x faxonii Trel. (alba x prinoides)

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