What is an American tree of the genus Populus or polar, having the seeds covered with abundant cottonlike hairs; esp., the P. monilifera and P. angustifolia of the Western United States called?

cottonwood — An American tree of the genus Populus or polar, having the seeds covered with abundant cottonlike hairs; esp., the P. monilifera and P. angustifolia of the Western United States. (Webster's 1913.)

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