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FNA | Family List | FNA Vol. 7 | Salicaceae | Populus

5. Populus deltoides W. Bartram ex Marshall, Arbust. Amer. 106. 1785. (as deltoide).

Eastern cottonwood, cotonier

Plants to 55 m, 35 dm diam.; moderately to strongly hetero-phyllous, (often 2 or more trunks near base). Bark light brown, deeply furrowed. Branchlets yellow-brown, becoming tan by third year, round or 5-angled, coarse or not, (1-)2-3.5(-6) mm diam., glabrous or thinly long-hairy. Winter buds greenish yellow, glabrous or stiffly hairy, resinous (resin yellow, moderately fragrant); terminal buds (6-)8-15(-21) mm; flowering buds separated on branchlets, (8-)14-20(-28) mm. Leaves: petiole distally flattened at right angle to plane of blade, (1-)3-8(-13) cm, about equaling blade length, (glabrous); blade broadly triangular-ovate, (1-)3-9(-14) × (1.5-) 3-9(-16.5) cm, w/l = 4/5-6/5, base truncate to cordate or broadly cuneate, basilaminar glands 0-6, round or tubular, margins translucent, ciliate, apex abruptly short- or long-acuminate, surfaces grayish green to bright green, glabrous (or visibly pilose only at emergence); preformed blade margins coarsely crenate-serrate midblade, teeth (3-)5-15(-30) on each side (graded, rounded), sinuses (0.4-)0.7-5(-7) mm deep; neoformed blade margins crenate-serrate, teeth (10-) 25-40(-55) on each side (graded), sinuses (0.1-) 0.5-1.5(-3) mm deep. Catkins loosely (3-) 15-40(-55)-flowered, (0.7-)5-18(-24 in fruit) cm; floral bract apex deeply cut, not ciliate. Pedicels 1-13(-17 in fruit) mm. Flowers: discs saucer-shaped, not obviously oblique, entire, 1-3(-4) mm diam.; stamens 30-40(-55); anthers truncate; ovary (3- or)4-carpelled, ovoid; stigmas 2-4, platelike, spreading. Capsules ovoid, (4-)8-11 (-16) mm, glabrous, (3- or)4-valved. Seeds (3-)7-10 (-23) per placenta. 2n = 38.

Subspecies 3 (3 in the flora): North America, n Mexico.

1 Leaf blades: apices long-acuminate, bases usually with 2 round basilaminar glands; pedicel lengths uniform, 1-6(-8 in fruit) mm.   5b Populus deltoides subsp. monilifera
+ Leaf blades: apices short-acuminate, bases usually with 0 or 3-6 tubular basilaminar glands; pedicel lengths progressively graded or uniform, 1-13 (-17 in fruit) mm   (2)
2 (1) Winter buds usually glabrous; leaves: basilaminar glands 3-6, abaxial surface pilose at emergence; neoformed blades: lengths usually distinctly greater than widths; pedicel lengths graded (shorter from base to apex).   5a Populus deltoides subsp. deltoides
+ Winter buds pubescent; leaves: basilaminar glands 0, abaxial surface glabrous at emergence; neoformed blades: lengths usually less than widths; pedicel lengths uniform..   5c Populus deltoides subsp. wislizeni

Lower Taxa


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