|Populus deltoides subsp. monilifera|
W.Bartram ex Humphry Marshall
Populus deltoides, the eastern cottonwood, is a cottonwood poplar native to North America, growing throughout the eastern, central, and southwestern United States, the southernmost part of eastern Canada, and northeastern Mexico. It is a dicot.
Populus deltoides is a large tree growing to 20–40 m (66–131 ft) tall and with a trunk up to 1.8 m (5.9 ft) diameter, one of the largest North American hardwood trees. The bark is silvery-white, smooth or lightly fissured when young, becoming dark gray and deeply fissured on old trees. The twigs are grayish-yellow and stout, with large triangular leaf scars. The winter buds are slender, pointed, 1–2 cm long (.039–0.79 inches), yellowish brown, and resinous. It is one of the fastest growing trees in North America. In Mississippi River bottoms, height growth of 10–15 ft per year for a few years have been seen. Sustained height growth of 5 foot height growth and 1 inch diameter growth per year for 25 years is common.
The leaves are large, deltoid (triangular), 4–10 cm (1.6–3.9 in) long and 4–11 cm (1.6–4.3 in) broad with a truncated (flattened) base and a petiole 3–12 cm (1.2–4.7 in) long. The leaf is very coarsely toothed, the teeth are curved and gland tipped, and the petiole is flat; they are dark green in the summer and turn yellow in the fall (but many cottonwoods in dry locations drop their leaves early from the combination of drought and leaf rust, making their fall color dull or absent). Due to the flat stem of the leaf, the leaf has the tendency to shake from even the slightest breeze. This is one of the identifying characteristics.
It is dioecious, with the flowers (catkins) produced on single-sex trees in early spring. The male (pollen) catkins are reddish-purple and 8–10 cm (3.1–3.9 in) long; the female catkins are green, 7–13 cm (2.8–5.1 in) long at pollination, maturing 15–20 cm (5.9–7.9 in) long with several 6–15 mm (0.24–0.59 in) seed capsules in early summer, which split open to release the numerous small seeds attached to cotton-like strands.
- Populus deltoides subsp. deltoides, eastern cottonwood is found in southeastern Canada (the south of Ontario and Quebec) and the eastern United States (throughout, west to North Dakota to Texas).
- P. d. monilifera (Aiton) Eckenw., the plains cottonwood (syn. P. deltoides var. occidentalis Rydb.; P. sargentii Dode) ranges from southcentral Canada (southern Alberta, Saskatchewan, and Manitoba) to the central United States and south to northern New Mexico and Texas.
- P. d. wislizeni (S.Watson) Eckenw., the Rio Grande cottonwood (syn. P. wislizeni (S.Watson) Sarg.; P. fremontii var. wislizeni S.Watson) grows from southern Colorado south through Texas to northeastern Mexico (Chihuahua, San Luis Potosi), and west to Arizona (presence in California, listed by GRIN, is doubtful, not included in the Jepson Flora of California). (Note: Some sources mistakenly spell the epithet "wislizenii." Correct spelling is with one "i," per ICN article 60C.2.)
It needs bare soil and full sun for successful germination and establishment; in natural conditions, it usually grows near rivers, with mud banks left after floods providing ideal conditions for seedling germination; human soil cultivation has allowed it to increase its range away from such habitats.
In vitro culture
A high frequency direct plant regeneration protocol has been described by Rakesh Yadav et al., 2009.
Oldest and largest
Eastern cottonwoods typically live 70 to 100 years, but they have the potential to live 200 to 400 years if they have a good growing environment.
Currently, the Balmville Tree is the oldest eastern cottonwood in the United States.
- The US national champion Populus deltoides var. deltoides is located in Sheridan County, Kansas and measures 96 ft (29 m) tall, 127 ft (39 m) wide with a trunk circumference at breast height (CBH) of 35 ft 7 in (10.85 m).
- The US national champion Populus deltoides var. monilifera is located in Ravalli County, Montana and measures 112 ft (34 m) tall, 94 ft (29 m) wide with a trunk circumference at breast height (CBH) of 32 ft 10 in (10.01 m).
- The US national champion Populus deltoides var. wislizeni is located in Bernalillo County, New Mexico and measures 84 ft (26 m) tall, 83 ft (25 m) wide with a trunk circumference at breast height (CBH) of 32 ft 9 in (9.98 m).
The largest recorded cottonwood tree in the world is the Frimley Park tree located in Hastings, New Zealand.
- Germplasm Resources Information Network: Populus deltoides
- Barnes and Wagner, Michigan Trees, University of Michigan Press, 2004
- USGS Aquatic and Wetland Vascular Plants of the Northern Great Plains: A successful, simple, reproducible, high frequency micropropagation protocol has been described by Yadav Rakesh et al., 2009  Populus deltoides
- v-Plants (Chicago Herbarium): Populus deltoides
- US Forest Service Silvics Manual: Populus deltoides
- Eckenwalder, J.E. (1977). "North American cottonwoods (Populus, Salicaceae) of sections Abaso and Aigeiros". Journal of the Arnold Arboretum 58 (3): 193–208.
- The Plant List: A working list of all plant species, Royal Botanic Gardens, Kew and Missouri Botanical Garden
- Jepson Flora: Populus; clicking 'next taxon' through the genus shows no entry for this taxon)
- J. McMeill et al. (eds). 2012. International Code of Nomenclature for algae, fungi, and plants. Regnum Vegetabile 154. Koeltz Scientific Books. ISBN 978-3-87429-425-6
- American Forests (2008). "Eastern Cottonwood Record". Retrieved February 27, 2013.
- American Forests (2012). "Plains Cottonwood Record". Retrieved February 27, 2013.
- American Forests (2012). "Rio Grande Cottonwood Record". Retrieved February 27, 2013.
- "Tree Information". The Zealand Tree Register. Retrieved 12 May 2012.
- "Tidbits". Ludington Daily News. Aug 4, 2001. p. 33. Retrieved 15 October 2015.
- Media related to Populus deltoides at Wikimedia Commons