Poplars & Willows
What are they?
Though poplars and willows may look superficially dissimilar, they are actually in the same family, a fact which is easily confirmed by a close look at their flower structures. In North America, several poplar species are called 'cottonwoods'. This family consists of a number of woody trees and shrubs with some of the trees being amongst the tallest and fastest-growing of hardwoods, making them popular for plantation trees.
Where are they found?
Most poplar and willow species favor wetlands but many species are grown as ornamentals and thus may be found on waste ground or on the site of former dwellings, even in dry conditions.
Identification
Identification of this group can at times be tricky and is often down to small details of the flower spikes. Plants in the horticultural trade are regularly sold under the wrong name which can also compound the problem, especially as many cultivated plants are hybrids or selected clones which may not be covered by most identification guides. Male and female flowers are carried on separate trees. Willows may or may not have stipules - small wing-like growths on either side of the leaf stem (petiole). These stipules may drop off shortly after the leaf expands in spring, or they may be persistent and are thus useful for species identification.
White Poplar Populus alba
Introduced from Europe. Widespread and locally common throughout Cape May County in waste ground and marginal habitats. Flowers March. Like Gray Poplar, this plant largely spreads itself vegetatively rather than by seed and is often found as expanding clumps of suckers. Almost all (perhaps all in North America?) plants are female which is a strong clue when the tree is in flower. Crown leaves can be very similar to Gray Poplar but almost always keep their white fluff longer, thus the tree looks paler overall. Strong growths, especially on basal suckers, have maple-like, lobed leaves.
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Gray Poplar above |
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| weakly toothed bract |
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Gray Poplar Populus x canescens
Introduced from Europe. Widespread and common throughout Cape May County in waste ground and marginal habitats. Flowers March. This plant is a hybrid between White Poplar Populus alba and the Old World Aspen P. tremula and, though it has several features of the latter parent, it strongly resembles the former and is much mistaken for it, to the point that many identification guides do not list it. Like White Poplar, this plant largely spreads itself vegetatively rather than by seed and is often found as expanding clumps of suckers. Almost all (perhaps all in North America?) plants are male which is a strong clue when the tree is in flower. The bracts within the catkins are strongly toothed at the apex. Young leaves are loosely light-gray downy below, the down falling away to leave green undersides with a few hairs in the vein axils.
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White Poplar on right |
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| strongly toothed bract |
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Bigtooth Aspen Populus grandidentata
Uncommon but small clumps are occasionally found scattered mostly in the northern half of the county, in wooded areas. Flowers April. Leaves larger than other poplars with well-marked teeth around the edge. New leaves furry, but this is soon lost, leaving a smooth, light green leaf on both surfaces. In older publications, this species is much over-recorded where specimens of Gray Poplar have been misidentified, particularly in the south of the county.
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white fluff |
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American Aspen Populus tremuloides
(Quaking Aspen) Native to North America but almost certainly an introduction in Cape May County and currently only known where clearly originally planted. Flowers March to April. Leaves smaller, more rounded and with much smaller marginal teeth than Bigtooth Aspen.
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Black Poplar Populus nigra
Native to Europe. Occasionally planted and persisting in a few locations. Trees in our area are of the upright variety 'italica', often known as Lombardy Poplar.
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Eastern Cottonwood Populus deltoides
Likely to be native in the deeper, alluvial soils of the Delaware Valley in Northern New Jersey, but at Cape May only occurs where it is planted on roadsides and along field edges. Flowers late March to early April. Leaves are broadly triangular, with strongly flattened petioles that flutter in the breeze. Capable of growing well over 100 feet in height.
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Swamp Cottonwood Populus heterophylla
A rare native, found in untouched swamps in the lower half of the peninsula. Flowers April. Leaves are distinctive for poplars in their rounded bases.
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Balsam Poplar Populus balsamifera
Introduced from western North America and occasionally planted in the wider countryside for lumber or as a shelter belt. Widespread and common throughout Cape May County in waste ground and marginal habitats. Flowers late March to early April. Most planted trees are male, bearing bright red catkins in spring. The strong aroma of balsam can be quite overpowering when the leaves break in the spring and gummy sap often stains the new leaves with amber. Young leaves in spring are bright lime green, soon becoming dark green with pale undersides.
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Black Willow Salix nigra
The common willow of the region, being frequent to common in wetlands and along the banks of permanent waterways. Flowers late April to May. Usually seen as a large bush or small to medium-sized, spreading tree. Leaves hairless below (or with a few hairs along the veins) and with rather short petioles. Leaves variable in shape; may be parallel-edged or slightly curved.
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& underside |
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White Willow Salix alba
An occasional escape from cultivation that may be found where garden refuse is discarded. Flowers late April to May.
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& stipules |
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Prairie Willow Salix humilis
Uncommon and currently only known from wooded clearings in the north of the county. Flowers April. Usually grows as a rather large bush rather than a tree. Leaves are coarsely woolly, especially below. At least some stipules are persistent and are rather narrow in outline.
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& stipules |
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Dwarf Prairie Willow Salix occidentalis
An uncommon, low, shrubby willow that occurs at a few grassy sites in the middle of the county. Flowers April. Stipules small and usually not persisting for long. Bushes often bear 'leaf rosettes' at the stem tips - the result of a gall insect attack.
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& stipules |
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Missouri Willow Salix eriocephala
(Heart-leaved Willow) Occasional around permanently wet areas such as old sand pits and ponds. Flowers late April to May. Old records are confused as the name Heart-leaved Willow has been used for both this species and for Salix cordata, while the current species was previously known as Salix rigida. Leaves hairless and slightly bluish underneath.
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Weeping Crack Willow Salix x pendulina
An ornamental weeping willow, less common than the Golden Weeping Willow but occasionally planted in public parks and similar places. Flowers April. Forms an attractive weeping tree but doesn't have the golden color of the following species. Weeping Crack Willow is believed to be a hybrid between the Crack Willow (Salix fragilis) and S. babylonica of China, which originated under cultivation in Europe. However, there are a number of varieties with variable traits and more than one hybrid cross may be involved. Flowers on this form are female only.
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female parts |
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Golden Weeping Willow Salix x sepulcralis nothovar. chrysocoma
An ornamental weeping willow, this golden form is the most popular variety and is often found planted in public places such as parks and golf courses. Flowers April. Spectacular when in flower as the golden color is really at its best then. Flowers most often have both male and female parts (unusual in willows) but may also be male only.
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