Eastern Cottonwood Fact Sheet
Family: Salicaceae - Willow family
Latin name: Populus deltoides
Common name: Eastern cottonwood
Most photos on this page are of a tree in Naperville, Illinois, along the west branch of the DuPage River.
Click on second leaf photo for enlargement to see flattened stem and glands at base of leaf.
- Male and female flowers develop on separate trees.
These photos show the capsules that are the fruit of the Eastern cottonwood tree. Female
flowers elongate to 15 to 30 cm (6 to 12 in).
capsules have short stalks and grow on long catkins. Each capsule has 3 or 4 valves. The
"cottony" material inside the capsule helps the wind carry the seeds. There
may be 30 to 60 seeds per capsule.
leaves of Populus deltoides are triangular. They are 3 to 5 inches long and nearly as wide. They
are dark green, lustrous above, and paler and smooth beneath. The marginal teeth
are rounded and somewhat hooked. The teeth near the base of the leaf are smaller than those
toward the pointed tip.
- The leaves of Populus deltoides have two glands near the stem.
- The stems of many kinds of poplars are flattened near the leaf and look as though they've
been pinched. That's why the leaves of the Cottonwood and its relatives are usually in
motion. Even a slight breeze can make them flutter.
- Flowering and Fruiting- Eastern cotton wood is dioecious, which means
that male flowers and female flowers are produced on different trees. Only the female
flowers will develop into fruit. The floral buds develop in the summer and open during
spring of the following year. Flowering occurs from February to April before leaves appear.
Male flowers are only 8 to 13 cm (3 to 5 in) long. They have 40 to 60 stamens and are
reddish in color and more conspicuous than the female flowers. Female flowers elongate
to 15 to 30 cm (6 to 12 in). Males tend to flower a few days earlier than females. Trees
as young as 4 to 5 years old have flowered.
- Seed Production and Dissemination- Seed production starts when the
trees are 5 to 10 years old, increasing rapidly in amount as the trees become older and
larger. Cottonwood trees usually have good seed crops.
- Seed dispersal follows flowering by about 2 months in southern populations and a somewhat
shorter period in the North. Seed dispersal occurs
from May through mid-July in the South and June through mid-July in the North. Seeds
may be carried several hundred feet by the wind, aided by the "cotton" attached to the seed. Seeds falling in water may be carried a long distance
from the parent tree before being left on silt deposits.
- Seedling Development- Unless floating on or immersed in water, cottonwood
seeds must reach a favorable seedbed and germinate very soon after falling. Germination
of fresh seeds may exceed 90 percent. Seedlings are delicate for the first few weeks.
Rains, very hot sunshine, and damping-off fungi kill many of them. Very moist, exposed
mineral soils, such as fresh silt deposits, are required. Germination is epigeal. Growth
rate of the fragile seedlings is slow for the first 3 weeks but may be very rapid after
that. Full sunlight for a substantial part of each day is required after the first few
Manual Volume 2 - Eastern Cottonwood http://www.na.fs.fed.us/pubs/silvics_manual/Volume_2/populus/deltoides.htm
- Unlike mose of the photos on this site, the ones on this page were not taken at Morton Arboretum.
- Last photo on page, male flowers
of Populus deltoides is courtesy of Al Schneider @ USDA-NRCS PLANTS Database
Karren Wcisel © copyright
Send email to Karrenw@aol.com
Please ask for permission before using my photographs. Larger sizes and additional photographs
of the tree are often available.
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