Stacy Susann Slodysko
~Populus~ Aspens, Cottonwoods, and Poplar
These are quick growing, soft-wooded trees of considerable commercial and
some ornamental importance. It consists of 51 different species throughout the northern hemisphere. Listed are some of the botanical featues that distinquish this genus from others:
"Leaves: Broadly triangular-lozenge shaped, sometimes round or lancelate. Long petiole. Tend to vary in shape according to the kind of shoot or their place on the shoot ( foliar polymorphism )
Buds: Elongated often pointed covered by several overlapping scales. Terminal bud larger than the lateral buds
Shoots: Circular or angular. Pith cross-section pentagonal
Flowering: Before leaves. Catkins pendulous. Flowers: oblique perinath, cup shpaed without nectaries.

Bracts irregularly denticulate, shed rapidly.

Stamens numerous, 5 to 50, with ususally reddish

Information regarding distinguishing features was taken from:
International Poplar Commission.Poplars and Willows in wood production and land use. FAO Forestry and Forest Products Studies, No. 12. 1958.

Scientific Name Common Name Scientific Name Common Name
Populus acuminata P. illicitana
P. adenopoda P. jacquemontiana
P. alba White Poplar, Silver Leaf P. koreana
P. augustifolia Narrowleaf Cottonwood P. lasiocarpa
P. ariana P. litwinowiana
P. balsaminfera Basalm Poplar P. macrophylla
P. bolleana P. mauritanica
P. bonnetiana P. maximowiczii
P. canescens Gray Poplar P. nigra Black Poplar, Lombardy
P. caspica P. nivea
P. ciliata P. paletzkyana
P. comesiana P. peroneana
P. davidiana P. pruinosa
P. deltoides Necklace, Eastern Cottonwood P. sargentii
P. denharditorium P. sieboldii
P. diversifolia P. simonii Simon's
P. euphratica P. suaveolens
P. fremontii Fremont P. szechuanica
P. glandulosa P. tacamahaca
P. glaucicomans P. tremula
P. grandientata Bigtooth Aspen P. tremuloides Quaking Aspen, Trembling Aspen
P. heterophylla Downy, Swamp Cottonwood, Swamp Poplar P. trichocarpa Western Poplar, Black Cottonwood, California Poplar
P. hickeliana P. violascens
P. hybrida P. wilsonii
P. ilicifolia
Southern species are thornless wwith leaves usually less than 3 times as long as they are wide
Male and female flowers are tiny and crowded in narrow catkins, keep in mind that the seperate
sexes are found on seperate trees. Most of the species in this genus can be found in the colder
regions. There ares even tree species that occur in the south east, some extending far beyond
this region. Below is a key that will aide in identification of the different species found:

1. Outer end of petioles conspicously flattened
2. Leaves with a narrow translucent border
3. Small glands on the upper side of base of most blades at junction with petiole; crown not columnar. 1. P. deltoides
3. Such glands absent; crown usually nearly columnar. 2.P. nigra
2. Leaves lacking translucent border
4. Leaves with 5-18 teeth on a side; buds dull brown, finely hairy
3. P. grandidentata
4. Leaves with 20-40 teeth on a side; buds shiny, glabous, or lowest scales
4. P. tremuloides
1. Outter end of petioles terete or nearly so
5. Leaves white-felted or gray hairy beneath, teeth less than 15 on each side
5. P. alba
5. Leaves glabrous beneath, or with other types of hairs, teeth more than 15 on
each side. 6. Terminal buds sticky to touch, with an odor of balsam 6. P. balsamifera
6. Terminal buds not sticky to touch, without odor of balsam
P. heterophylla"

General Information

The genus, populus, which includes the aspens, cottonwoods, and balsam poplars can be found ranging from the forests of northern Africa, the Himalaya, China, and Japan northern beyond the Artic circle. In the new world poplars can be found from Alaska and Canada to northern Mexico.

Throughout much of the world, one can find many hybrids and clones of poplars. These species are normally obtained for ornamental usage. This has its disadvantages, which include; early decline and breakup, insect pests and diseases, and aggressive roo t invasion and occlusion of sewers and drain pipes.

Throughout the genus, the high value of the wood as a source of pulp veneer and lumber coupled with some extremely rapid growth rates have promoted much activity by forest-tree geneticists.

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