Populus nigra L. - Black Poplar, Lombardy Poplar
Common Names
Black Poplar, Lombardy PoplarField Identification
Tree with opposite, simple leaves.Other uses
The use of poplars for removal and sequesterization of various heavy metals and other chemicals from contaminated soils (phytoremediation) has been explored.Possible use as biomonitors of air pollution (Sawidis et al, 1995) (Ballach, 1997).
Initially Populus nigra 'Italica' was widely used as an ornamental; but its use as a street tree quickly fell from favor due to its weak wood which caused breakage; its roots which disrupted sidewalks and penetrated and clogged water and sewer pipes; and susceptibility to a canker-forming fungus which kills the tree. By the 1870's it was banned as a street tree and replaced in many cities including Brooklyn. Populus nigra 'Italica' was originally found on the banks of the Po River in Italy sometime between 1700 and 1720; some have speculated that it actually originated in Persia or the Himalayan region. First introduced into North America by William Hamilton near Philadelphia in 1784, it quickly became popular and by 1798 the Princeton Nursery in Flushing, New York advertised 10,000 for sale. While its use as a street tree quickly fell from favor, it was still in demand in the late 1800's in America for emulating the Italianate villa style (Wood, 1994).
Nomenclature
Populus nigra L., Sp. Pl. 1034. 1753.
Populus versicolor Salisb., Prodr. Stirp. Chap. Allert. 395. 1796.
Populus nigra sinensis Carr., Rev. Hort. 1867: 340. 1867.
Populus nigra var. genuina Wesmael, De Cand., Prodr. 16,2: 328. 1868.
Populus viadri Rudiger, Gartenfl. 39: 447. 1890.
Populus nigra var. typica Beck, Fl. Nieder-Oster. 303. 1890.
Populus europaea Dode, Bull. Soc. Hist. Nat. Autun. 18: 209, t. 12, fig. 78. 1905.
Populus sinensis (Carr.) Dode, Soc. Hist. Nat. Autun. 18: 208, t. 12, fig. 72. 1905.
TYPE: unknown
Populus nigra var. italica (Munchh.) Koehne, Deutsche Dendr. 81. 1893.
Populus nigra italica Munchh., Hausvat. 5: 230. 1770.
Populus pyramidalis Salisb. Prod. 395; Roxier, ex Lam. Encyc. v. 235.
Populus italica Duroi Harbk. ii. 141.
Populus dilatata Ait. Hort. Kew. ed. I. iii. 406.
Populus fastigiata Moench.
Populus nigra 'Italica' Moench
TYPE: unknown
Description
HABIT Perennial, deciduous, phanerophytic, tree, diclinous and dioecious, up to 30 m tall. The commonly encountered 'Italica' is a fastigiated mutation of a male originally found in Italy; it has a very slender upright crown (column-like), with only a spread of 10 to 15 feet, (Wood, 1994).
STEMS Main stems erect, round. Bark initially smooth and gray-green, becoming darker (gray to nearly black) and irregularly furrowed, not exfoliating. Branches erect or ascending. Twigs light brown to yellow-brown or greenish yellow or gray, not odoriferous, terete, 2-5 mm in diameter, smooth, glabrous, eglandular. Pith brown, 5-pointed, continuous, nodal diaphragm absent. Sap translucent. For a synopsis of the root system see Stettler et al, 1996. Roots able to form both ecto- and endomycorrhizal associations. (Vozzo & Hacskaylo, 1974)
BUDS Terminal and axillary present, monomorphic, scattered along stem; terminal bud ovoid, pointed, viscid; axillary buds 1 per axil, ovoid, pointed, viscid. Bud scales brown to reddish-brown, imbricate, chartaceous, glabrous, eglandular. Bud scale scars not encircling the stem. Leaf scars crescent-shaped. Vascular bundle scars 3, crescent-shaped. For an overview of the anatomical structure of the bud scales see Sentsov, 1995 (In Russian).
LEAVES Alternate, simple, 1 per node, spaced somewhat evenly along and divergent from stem. Stipules present, lateral, caducous, free from the petiole, leaf-like. Leaves petiolate, petiole flattened, 3-6 cm long, glabrous, eglandular. Leaf blades: abaxial surface light green, adaxial surface green, ovate or rhombic or widely ovate or widely rhombic or widely deltate, bilaterally symmetric, 3.5-10 cm long, 2.5-10 cm wide, chartaceous, base cuneate or truncate, margin serrate to crenate with minute glands on teeth, apex acuminate. Abaxial surface glabrous, eglandular. Adaxial surface glabrous, eglandular (occasionally with 1-2 small, sessile glands at base near junction with petiole). Leaves sometimes dimorphic- with leaves borne on long shoots larger, and deltoid or rhombic-ovate in shape; while leaves borne on the shorter lateral branches are smaller and have more of a rounded shape. For an overview of the secondary leaf tissues see Stettler et al, 1996.
FEMALE INFLORESCENCES Unisexual, axillary raceme, precocious, formed on last season's growth, pendant; catkin-like; 8-15 cm long with about 50 flowers. Peduncle and rachis glabrous, eglandular. Bracts 1, subtending each flower, petiolate, adnate to pedicel, apices erose and ciliate, lateral surfaces glabrous, eglandular. Pedicels 1-1.5 mm long, glabrous, eglandular.
FEMALE FLOWERS Perianth parts indistinguishable from one another, fragrance absent. Gynoecium set on perianth which is a crateriform disk composed of connate tepals (perigon). Perigon persistent, glabrous, eglandular. Carpels 2-4. Locules 1. Stigmas 2, lobed. Styles 1. Ovary superior, ovoid, glabrous, eglandulart. Placentation parietal. For an investigation into the development, cytochemistry, and ultrastructure of the stigmas see Li et al, 1995.
MALE INFLORESCENCES Axillary raceme, precocious, formed on last season's growth, pendant catkin-like; 4-6 cm long. Peduncle and rachis glabrous. Bracts 1, subtending each flower, petiolate, adnate to pedicel, apices erose and ciliate, lateral surfaces glabrous, eglandular. Pedicels 1-1.5 mm long, glabrous, eglandular.
MALE FLOWERS Perianth parts indistinguishable from one another, fragrance absent. Androecium set on perianth which is a crateriform disk composed of connate tepals (perigon). Perigon persistent, glabrous, eglandular. Stamens 12-60, exserted. Anthers dehiscing longitudinal, glabrous, eglandular. Filaments free, straight, eglandular.
FRUITS Loculicidal 2-valved capsule, ovoid, glabrous, eglandular; with 4-25 seeds. ('Italica' fruitless)
SEEDS Minute (mean seed mass ranged from 0.80+ - 0.05 mg (Karrenberg & Suter, 2003); 0.3-0.6 mg (Bessey, 1904)), glabrous, eglandular, adnate tufts of longer "cotton" (which facilitate anemochory) composed of epidermal hairs of the placenta; endosperm completely consumed by developing embryo so that none remains in the mature seed (Nagaraj, 1952) (Burns & Honkala, 1990).
Habitat
Mesic to moist roadsides; alluvium.Distribution
Indigenous to Eurasia, naturalized throughout much of North America.
United States -- AL, AR, AZ, CO, CT, DC, DE, FL, GA, IA, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, PA, RI, SC, SD, TN, TX, UT, VA, VT, WI, WV, WY
Canada -- ON, PE (BC, NB, NF, NS, QC - reported but not specified whether escaping)
New York Metropolitan Region -- Nonnative, occasionally naturalized throughout the metropolitan area.
Rarity Status
Global Heritage Rank -- G5Species Biology
Flowering
April - May
Pollination
Anemophily
Fruiting
May
Dispersal
Anemochory and Hydrochory
Germination
It is difficult to define germination with the small seeds of Populus species; for most species; germinated seedlings should have well-developed hypocotyl hairs, regular growth, and a geotropic response. Seeds that have been dried for storage may suffer injury from rapid imbibition; aeration with humid air after storage has been used to solve this problem. The critical factor for germination is moisture. (Young & Young, 1992)
The time of ripening is quite variable; a safe criterion for time of fruit collection is when a small percentage of the capsules are beginning to open. Pre-strorage drying immediately after collecting is essential for successful storage. A moisture content of 5-8% improves viability and germination of stored seed. After air drying for 4 days store in a sealed container at 41d F. The critical factor for germination is moisture. (Dirr & Heuser, 1987)
Long term viability can be maintained with temperatures below freezing in a dry atmosphere. (Stettler et al, 1996)
Study in Western Europe showed on average, seed germinability remained rather low and close to 28%. However, large differences in germinability were observed between trees and over time. A continuously wet substrate was the most favorable condition for germination and seedling survival. A change from wet to submerged conditions increased germination and reduced seedling survival. (Guilloy et al, 2002)
Hybridizes with P. deltoides = P. x canadensis Moench. (=Populus x euramericana ?) (Fowells, 1965) (Stettler et al, 1996).