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Published In: Species Plantarum 2: 995–996. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 

Project Name Data (Last Modified On 8/18/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native

 

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7. Quercus nigra L. (water oak)

Pl. 414 e, f; Map 1845

Plants trees to 30 m tall. Bark medium gray, divided into low persistent ridges, the inner bark pinkish. Twigs 1–2 mm wide, dark brown, glabrous. Buds 3–5 mm long, dark brown or grayish, pubescent or the lower scales glabrous. Petioles 2–10 mm long. Leaf blade 5–11 cm long, 1.6–6.0 cm wide, narrowly angled to long-tapered at the base, divided shallowly or up to 70% of the width, the lobes 1(2) per side, the largest lobes above midpoint, often near the blade tip, even well-developed lobes usually a mere convexity on the leaf margin, if distinct then 10–20 mm wide, oblong or ovate, broadly rounded, undivided or with a distinct bulge on the lower margin, each with 0(–2) bristles 0.5–1.0 mm long (the whole blade with 0–7 marginal bristles), the secondary veins turning aside before reaching the margin or with 1 pair reaching the margin at the tips of the lobes and ending in bristles; the upper surface rather dull, glabrous, the undersurface green, glabrous or with inconspicuous unbranched appressed hairs, smooth to the touch, the vein axils with prominent tufts of 6–12-rayed, stalked hairs. Acorn cups 4–6 mm long, 13–14 mm wide, covering 20–40% of the nut, saucer-shaped to shallowly bowl-shaped, the inner surface smooth, hairy except near the rim, the outer surface with the scales tending to be distinctly convex-thickened at the base, pubescent. Nuts 11–13 mm long, 13–14 mm wide, depressed-ovoid, without concentric grooves around the tip. 2n=24. April–May.

Scattered in the Mississippi Lowlands Division (southeastern U.S. west to Missouri, Oklahoma, and Texas). Swamps, bottomland forests, banks of streams and rivers, and margins of lakes, oxbows, and sloughs; also ditches and fencerows.

Leaves of Q. nigra are quite variable morphologically and a number of forms have been described from material in other states to account for extremes in variation. Juvenile leaves or leaves from vigorous sprouts may be deeply lobed. A specimen from Dunklin County (Holmes 981, at the Missouri Botanical Garden Herbarium) appears to represent a hybrid with either Q. palustris or Q. texana, but the parentage cannot be confirmed. Other hybrids in Missouri appear to be quite uncommon, only Q. falcata and Q. phellos have been recorded to hybridize with Q. nigra in the state.

 


 

 
 
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