Populus fremontii

Populus fremontii, commonly known as Fremont's cottonwood or the Alamo cottonwood, is a cottonwood (and thus a poplar) native to riparian zones of the Southwestern United States and northern through central Mexico. It is one of three species in Populus sect. Aigeiros. The tree was named after 19th century American explorer and pathfinder John C. Frémont. The tree is native to the Southwestern United States and Mexico. In the United States, the species can be found in California, Idaho, Nevada, Utah, Arizona, New Mexico, Texas, and Colorado. In Mexico, it can be found in Baja California, Baja California Sur, Sonora, Chihuahua, Coahuila, Nuevo León, Mexico State, and Puebla. The riparian tree grows near streams, rivers, springs, seeps, wetlands, and well-watered alluvial bottomlands at elevations below 2,000 metres (6,600 ft) elevation. P. fremontii is a large tree growing from 12–35 m (39–115 ft) in height with a wide crown, with a trunk up to 1.5 metres (4 ft 11 in) in diameter. The bark is smooth when young, becoming deeply fissured with whitish cracked bark on old trees. The 3–7 centimetres (1.2–2.8 in) long leaves, are cordate (heart-shaped) with an elongate tip, with white veins and coarse crenate teeth along the sides, glabrous to hairy, and often stained with milky resin. Autumn colors occur from October–November, mainly a bright yellow, also orange, rarely red. The inflorescence consists of a long drooping catkin, which blooms from March to April. The fruit is a wind dispersed achene, that appears to look like patches of cotton hanging from limbs, thus the name cottonwood. The largest known P. fremontii tree in the United States grows in Skull Valley, Arizona. In 2012, it had a measured circumference of 557 inches (14,100 mm), height of 102 feet (31 m), and a spread of 149.5 feet (45.6 m). Two subspecies are currently recognized. Some confusion due to hybridization with a Rio Grande subspecies of Populus deltoides subsp. wislizeni had originally placed this eastern cottonwood subspecies as a P. fremontii subspecies, but it was removed in 1977.