Different Cultivars of Poplar
(James Eckenwalder)
Description of some important old clones
Populus
nigra Linnaeus "Italica"
Lombardy poplar - Male clone with a narrow columnar crown of long, upright branches; large trunks heavily buttressed; bark light brown on branches, dark grayish brown and deeply furrowed on large trunks; first-year twigs round, orange, smooth and a little shiny; winter buds 10-20 mm long, sticky with reddish orange resin, not hairy. Leaves light green above and beneath; preformed (early) leaves of the numerous short shoots 5-8 cm long, somewhat diamond-shaped, finely toothed along both sides, with a wedge-shaped base; neoformed (late) leaves of long shoots 3-9 cm long, wider than long, roundly triangular, with an abrupt, short point, finely toothed along the whole lenght. Flower bracts white, deeply cut, without marginal hairs; flowers numerous; stamens 12-20.
Lombardy poplar is particularly short-lived, often succumbing to Dothichiza canker and other diseases within 10 years. The same malady seems to affect other P. nigra clones. Lombardy poplar has no direct role in plantation culture but is a parent or grandparent of many other important clones.
Populus
x canadensis Moench "Allenstein"
(DN1) - Female clone with a narrowly egg-shaped crown of long, rising branches; large trunks cylindrical; bark greenish gray on branches, dark brown and strongly furrowed on large trunks; first-year twigs light grayish brown, weakly 5-angled and slightly ridged, hairless, dull; winter buds 8-18 mm long, sticky with reddish resin, not hairy. Leaves bright green above, paler beneath, 5-7 cm long, heart-shaped or with a broadly rounded base, finely toothed along the whole edge, the petiole 3-4 cm long, flattened side to side at the blade, hairless. Flower bracts white with brown edges, deeply cut; flowers many, but not tightly spaced; seed capsules opening with 2-3 valves.
This clone from Germany is a fast grower at about 12-15 dm in height per year and puts much of its biomass into the straight trunk rather than the relatively slender branches. Substantial rust susceptibility can lead to early defoliation as can early frosts.
Populus
x canadensis Moench "Blanc du Poitou"
(DN19) - Male clone with a broad, oval crown of long, gently rising branches; large trunks cylindrical; bark light brown, becoming dark grayish brown and shallowly furrowed on large trunks; first-year twigs greenish brown, distinctly 5-angled with prominent ridges, hairless, slightly shiny; winter buds 6-12 mm long, sticky with pal resin, not conspicuously hairy. Leaves dull bluish green on both sides, 5-8 cm long, heart-shaped or with a straight-across base, with a short, narrow tip, finely toothed along the whole edge, with small, elongate glands at the base near the petiole, which is 3,5-7 cm long, red, and flattened side-to-side at the blade. Flowers bracts white with the deeply cut edges brown; flowers numerous; stamens about 20-30.
Another old clone (ca. 1870) from France that is still used in plantation culture, it is tolerant of late frosts due to its late flushing, but also retains its leaves late and so has a reasonable growth rate. Its susceptibility to diseases varies greatly with site.
Populus
x canadensis Moench "Eugenei" (Carolina poplar)
(DN34) - Male clone with a broadly conical crown of long, rising branches; large trunks cylindrical to somewhat fluted; bark light tan with an orange cast on branches, becoming grayish tan and deeply furrowed on large trunks; first-year twigs round, yellowish orange, hairless, slightly shiny; winter buds 1-2,5 cm long, very sticky with reddish orange resin. Leaves bright green above, paler and a little duller beneath, the petiole (3)-6-8 cm long, strongly flattened side-to-side at the blade; preformed (early) leaves of short shoots 4-10 cm long, angularly egg-shaped, with about 15-25 graded teeth along the middle of each side, the base broadly wedge-shaped and shouldered below the teeth, sometimes with a single round gland at the petiole the tip drawn out in a long point; neoformed (late) leaves of long shoots 6-11 (-14) cm long, broadly egg-shaped, with about 30-35 teeth along most of the side, the base broadly rounded, the tip with a short point. Flowers bracts white with brown tips, deeply cut, hairless; flowers numerous; stamens 20-30.
This is, by far, the most prevalent Euramerican clone ( P. nigra italica x P. marilandica) in general cultivation in North America. It has been planted for so long and is so pervasive that land managers, naturalists, foresters, and botanists across the continent often mistake it for the native P. deltoides (one of its parents) or P. fremontii, depending on the region. Although not itself widely used in plantation culture, it has been used in breeding programs and has passed on its relatively narrow crown, inherited from its Lombardy poplar parent. The Carolina poplar is relatively free from pests and diseases and, in the Great Lakes region, in contrast to other regions, it is an important commercial clone, one of the few recommended in the region for plantations and windbreaks around orchards.
Populus
x canadensis Moench "I 45/51"
Male clone with a broad conical crown of long, rising branches from a straight trunk; large trunks round and strongly tapering; bark tan on branches, quickly becoming grayish brown and furrowed on large trunks; first-year twigs pale greenish brown, strongly angled with prominent ridges, glossy, hairless; winter buds 5-18 mm long, only slightly sticky with reddish resin, hairless. Leaves slightly bluish green above and beneath, 5-8 cm long, heart-shaped but with a flat base, tip short-pointed, finely toothed along almost the whole margin, the petiole about 2,5-4 cm long, pale red, flattened side-to-side at the blade. Flowers bracts white with a dark brown, deeply cut edge; flowers numerous; stamens about 20-30.
This Italian clone has good growth on heavy soils as wel as on better ones. Il is fairly susceptible to pests and diseases but has more use in plantation culture than in horticultural or amenity plantings.
Populus
x canadensis Moench "Regenerata"
(DN16) - Male clone initially with a narrowly cylindrical crown of short rising branches but ultimately broadly rounded and irregular, large trunks cylindrical; bark brown on branches becoming dark gray and furrowed on large trunks; first-year twigs dark brown, 5-angledand prominently ribbed, hairless and somewhat shiny; winter buds 5-15 mm long, very sticky with reddish resin, not hairy. Flower bracts white with brown edges, sharply cut; flowers numerous; stamens about 20-30.
This very old clone (ca. 1814) from France has a modest growth rate for a Euramerican hybrid of about 10-12 dm in height per year. In compensation, perhaps, it is relatively resistant to diseases. Like other older clones, it is now largely replaced by more recent and faster growing clones, but still retains some use in horticultural and amenity plantings.
Populus
x canadensis Moench "Robusta"
(DN17) - Male clone with a broadly conical crown of long, rising branches; large trunks cylindrical: bark greenish gray on the branches, quickly becoming dark gray and furrowed on trunks; first-year twigs light reddish brown, round, except slightly angular on especially robust shoots, hairless; winter buds 5-18 mm long, only slightly sticky with reddish resin, hairless. Leaves shiny yellowish green on both sides, 6-10 (-12) cm long, roundly triangular with short triangular tip, the base fairly flat across and with small glands at the petiole, toothed along almost the whole edge, the petiole 3,5-5 cm long, red, flattened side-to-side at the blade, hairless. Flower bracts white with light brown tips, deeply cut; flowers many; stamens about 20-25.
This old (ca. 1895) clone from France has good growth at 12-19 dm in height per year, which is achieved partly through early flushing and late leaf fall, making it susceptible to damage by late spring frosts. The newly flushing foliage is bright red, while other clones of Euramerican hybrids range from green through brown and dull red to dark purple. It is prone to develop stem cankers at wounds. Still used to some extent in plantations in Europe, it is mostly used in horticultural and amenity plantings in North America.
Populus
x generosa A. Henry "20-88-183"
Populus trichocarpa x Populus deltoides - Female clone with a spreading crown of slender horizontal branches; large trunks cylindrical and straight; bark greenish gray on branches, light brown and scaly on young trunks, becoming deeply furrowed with age; first-year twigs darks reddish brown, cylindrical to 5-angled, hairy; winter buds 10-20 mm long, very sticky with reddish, fragrant resin. Leaves dark green above, strongly whitened between the prominent veins beneath, up to 20-23 cm long, heart-shaped, with numerous coarse, rounded teeth along the whole margin, but shallower near the triangular tip and shouldered and heart-shaped base marked by 2 or more domed to fingerlike glands at the junction with the 9-10 cm long, reddish green, flat-topped round petiole. Flower bracts deeply cut, white with brown tips; flowers numerous and densely packed; seed capsules opening with 3-4 valves.
The enormous leaves of this clone that was bred by Brian Stanton (James River Corp., Camas, WA) have yellow to red veins on the upper surface. The toothing is remarkably uniform as it follows the wavy margin, which is a distinctive feature among commercial clones of P. x generosa. The straight stem is due in part to strong apical dominance, preventing the crown from breaking up into major branches.
Populus
"Androscoggin"
Populus maximowiczii c Populus trichocarpa - Male clone with a broad, egg-shaped crown of long, rising branches; large trunks cylindrical; bark gray on branches, becoming dark grayish brown on large trunks; first-year twigs greenish brown, sharply 5-angled with prominent, corky ribs, densely fuzzy; winter buds 8-14 mm long, sticky with reddish brown, fragant resin. Leaves dark green above, white beneath, 7-10 cm long, egg-shaped, finely and evenly toothed along the whole edge, the tip short, the base heart-shaped, the petiole 2,5-3,5 cm long, red, round at the blade. Flower bracts white with light brown edges, deeply cut; flowers numerous and fairly densely packed; stamens about 30-40.
This fast-growing clone from the Oxford Paper Company breeding program in the 1930s is entirely balsam poplar in parentage and characteristics. It has a long growing season, with early leaf flush and late leaf drop, although leaf loss can be accelerated by rust infection to which this clone has moderate susceptibility. It is otherwise relatively disease and pest resistant and is suitable for plantation culture in less continental areas of northeastern North America. However, in the more continental climate of the Great Lakes region and even in the St Lauwrence valley of Quebec, it is one of the worst available commercial clones because of its extreme susceptibility to Septoria canker.
Under construction...
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