A fast-growing, characteristically shrubby species (2), the flat-leaved willow (Salix planifolia) is a distinctive perennial plant with smooth, grey bark (3) (4). The branches are yellow-brown, reddish-brown, dark brownish or violet, and may be hairless, or with a covering of short or long hairs. The branches are occasionally coated in a whitish, waxy bloom (2) (3) (5). The smaller branches may also be hairless, or with a soft covering of fine or dense, short, silky hairs (2) (5).
The flat-leaved willow has narrow, oblong-shaped leaves which are dark glossy green and usually hairless on the upper surface, and whitish below, sometimes with a white, waxy coating and a sparse covering of white or reddish, silky hairs (2) (3) (4) (5). The margins of the leaves are typically smooth, but they may also be slightly serrated or with small, rounded teeth (2) (5). The juvenile leaves of this species are usually reddish or yellowish-green (2).
The flat-leaved willow produces long, cylindrical, dense clusters of yellow-green flowers, called ‘catkins’, before the leaves emerge (2) (4) (5). The male catkins are one to four centimetres long and between 1 to 1.5 centimetres wide, and are usually stout and almost rounded. The female catkins are longer, reaching up to around six centimetres, and usually appear much slenderer than the male catkins (2). The catkins are initially compact, becoming fuller and fluffier throughout the flowering period (4).
- Also known as
- diamond-leaf willow, tea-leaved willow.
- Height: up to 4 m (2)
Flat-leaved willow biology
The flat-leaved willow usually produces catkins between May and June (5) (8), and begins fruiting from around June (8). It is dioecious, with the male and female flowers occurring on different plants (2) (4). At the base of each flower, there are one or two small glands which secrete sweetly-scented nectar to attract insects, particularly bees and moths, to pollinate the flowers (9). After the flowers have wilted, the male catkin dries up, while the female catkin turns green and lengthens as the fruit develops (4).
The small, capsule-like fruits of the flat-leaved willow contain an abundance of small, light-weight, cottony seeds, which the plant begins to produce at around two years old. When the fruit reaches maturity, it splits open and releases the seeds, which are dispersed by the wind and water (3) (4). The whole catkin may be shed when the seed is ripe, which often results in cottony drifts forming under the willow plant in late spring (9).
Flat-leaved willow range
A wide ranging species, the flat-leaved willow occurs from southern Yukon to Labrador in Canada, and south to Maine, New Hampshire, Vermont, Wisconsin, Minnesota and several other areas in the northern United States (3) (5) (6) (7). It is largely restricted to mountainous terrain in the United States, especially in the western parts of its range, where it occurs as far south as California and New Mexico (3).
Flat-leaved willow habitat
The flat-leaved willow inhabits wet mountain meadows, stream and lake edges, swamps, marshes, bogs and fens. It may also occur in woodland openings (3) (4) (5) (6) (7).
The flat leaved-willow is generally found at high-elevations in upland or mountainous regions (3) (5) (6), but may occur at any elevation between 100 and 4,000 metres (5).
Flat-leaved willow status
The flat-leaved willow has not yet been assessed by the IUCN.
Flat-leaved willow threats
Very few threats to the flat-leaved willow have currently been identified, although hiking and recreational use is thought to pose a potential risk to populations of this species in some areas (6).
Flat-leaved willow conservation
There are currently no conservation measures targeted specifically at the flat-leaved willow.
Recommended conservation actions include protecting this species’ habitat from natural disturbances and changes in water regimes along streams, river and lakes (10).
Find out more
Find out more about the flat-leaved willow:
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- Male and female flowers are borne on separate plants.
- An organ that makes and secretes substances used by the body.
- A plant that normally lives for more than two seasons. After an initial period, the plant produces flowers once a year.
- To transfer pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
IUCN Red List (July, 2011)
Argus, G.W., McJannet, C.L. and Dallwitz, M.J. (1999) Salicaceae of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Department of Biology, Memorial University, Canada. Available at:
Uchytil, R.J. (1991) Salix planifolia. In: Fire Effects Information System, (Online). U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Available at:
USA National Phenology Network - Salix planifolia (July, 2011)
Flora of North America - Tea-leaved willow, Salix planifolia (July, 2011)
Maine Department of Conservation, Rare Plant Fact Sheet - Tea-leaved willow, Salix planifolia (July, 2011)
Cody, W.J. (2000) Flora of the Yukon Territory. National Research Council of Canada Research Press, Ottawa.
Wisconsin Department of Natural Resources - Tea-leaved willow, Salix planifolia (July, 2011)
Heywood, V.H. (1978) Flowering Plants of the World. Oxford University Press, Oxford.
Michigan Natural Features Inventory - Tea-leaved willow, Salix planifolia (July, 2011)