Populus trichocarpa
| Standard Cyclopedia of Horticulture |
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Populus trichocarpa, Torr. & Gray. Black Cottonwood. Very large tree, to 200 ft. and trunk to 8 ft. diam., with wide head or top and upright branches: lvs. varying from narrow- to broad-ovate, truncate or cordate at base, acute or taper-pointed at apex, finely serrate, to 8-10 in. long, shining green above and rusty but becoming whitish beneath: catkins 2-5 in. long; stamens 40-60; pistillate catkins loose-fld., in fr. becoming as much as 10 in. long; ovary 3-carpelled: caps, nearly sessile. Calif, to Brit. Col. and Alaska, reaching an elevation of 6,000 ft. 8.8.9:493. G.F. 5:281. Aside from the conifers, it is said to be the largest tree in Ore. to Brit. Col. For P. hastata, see No. 17. Following are supposed hybrids in the balsam poplar group: (a) P. berolinensis, Dipp. (P. certinensis, Dieck. P. pseudo- balsamifra, Fisch.). Columnar tree supposed to be of hybrid origin, with short ascending branches, the growths densely pubescent and the young ones slightly winged but often becoming nearly or quite smooth at maturity: buds greenish, pointed, viscid: lvs. on strong shoots 3-4 in. long, ovate or ovate-rhombic, mostly rounded but sometimes cuneate at base, contracted into a long glandular acuminate point, glabrous on both surfaces, greenish or slightly whitish beneath, the margin not ciliate and with a very narrow translucent edge visible under a strong lens, the margins usually regularly crenate-serrate and sometimes with irregular shallow lobes. Perhaps a hybrid between Lombardy poplar and P. laurifolia. The name P. certinensis was applied to the staminate plant. Whether the P. Certinensis grown in N. Amer. (Fig. 3147) all belongs with P. berolinensis is very doubtful. Some of it seems to have many of the characters of P. deltoides. As grown in nurseries and collections here, it is a very rapid-growing and hardy tree, with a strong central leader and very heavy dense foliage; differs from P. monilifera as follows: lvs. broad-ovate in outline, with a rounded or tapering base and rather short point at the apex: the margin rather closely-toothed, wavy: If stalk comparatively short, only moderately flattened, glandless at the top; stipules present and conspicuous: bud long; shoots slightly hairy. The foliage on the old wood or upon slow-growing shoots is very unlike that upon the vigorous branches and is almost identical with that of the balsam poplar, being broadly oval, with finely serrate margins, and whitish beneath. The twigs, also, are cylindrical. But the strong shoots are strongly angled or grooved and the foliage is much like that of the native cottonwood. But darker; and the growth is more close and erect. The sketch in Fig. 3147 distinguishes the lvs. The Certinensis poplar is a more rugged tree than the cottonwood, with healthier foliage in the presence of If rust, and its wood is said to be valuable. It has been much planted in the N. W., and deserves to be widely distributed. Its effect in the landscape is considerably unlike that of the cottonwood. Its lvs. stand out more horizontally, while those of the cottonwood hang loosely and often vertically and therefore give the tree-top a heavier look. The terminal spray of the two is particularly distinguishable in this regard. The lvs. of Certinensis upon the strong, erect shoots stand almost at right angles to the shoot, and, at some distance, therefore, present only their ruffled edges to the eye, producing a unique and picturesque effect. The illustration (Fig. 3147) represents a top leaf of P. certinensis as grown in this country, but the name may not be correctly placed. (b) P. Wobstii, Schroed. (P. Wobsky. Hort.). Buds very viscid: lvs. 4 - 6 in. long and 2 in. broad, lanceolate, with widest part about the middle, narrow but rounded at base, gradually tapering toward the bluntly acuminate apex, slightly pubescent, white beneath, ciliate and crenate-serrate; petiole with few scattered hairs: branchlets glabrous. (c) P. Rasumowskyana, Schroed. Buds pointed, viscid: lvs. on young trees and vigorous shoots 4 x 3 in., orbicular ovate. rounded or sub- cordate at base, contracted above into a gland-tipped acuminate apex, very nearly glabrous, pale beneath, the margin glandular-crenate and not ciliate; petiole terete, grooved above: branchlets glabrous, ridged. P. Nolestii. as it has been grown in this country, is either this form or very like it, but is little understood. (d) P. Petrowskyana, Schroed. Very like P. Rasumowikyana, but with minute pubescence on branchlets and petioles; lvs. on vigorous shoots 5 x 4 in., ovate, cordate, the apex long-acuminate, pale beneath; serrations deeper than in last. VI. Variable-leaved Poplars. Lvs. remarkably polymorphous or diverse on the same plant, from very narrow to broad, coriaceous and reticulate, the petiole more or less cylindrical, the buds little if at all viscid: stamens few (about a dozen): caps, pedicellate, elongated; stigmas .
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