Fremont Cottonwood, Populus fremontii ssp. fremontii

Female catkins and leaves. The yellowish-green leaves are heart-shaped with coarsely scalloped margins and are often stained with milky resin. Petioles are flattened and ribbon-like, allowing leaves to quiver in the breeze. San Joaquin Wildlife Sanctuary, Irvine, CA. 4-16-11. © Joan Avise.	Fremont Cottonwood Populus fremontii ssp. fremontii A medium-sized single-stemmed shade-intolerant tree found in Aliso Canyon, Santa Ana Canyon, the southeast coast, Santa Ana Mountains and northern foothills. Once fairly common along the Santa Ana River (Roberts). A round gall is induced by the aphid-like insect Pemphigus populi-transversus on the leaf petiole close to the blade (Clarke). Buds at the branch tips are sharp pointed with overlapping scales. The bark of older trees has whitish, flat-topped ridges separated by furrows. The wood is used for firewood, fence posts and pallets, and serves as an indicator of surface water. It provides critical habitat for wildlife. Native to riparian zones of the Southwestern United States and northern through central Mexico. Back to Salicaceae of Orange County, California Back to Eudicots of Orange County, California Back to Natural History of Orange County, California
Mature trees are 40-90 ft. in height, and become established on disturbed sites in moist places along river banks, washes and streams at lower elevations, growing rapidly from seed, the primary means of propagation. Cottonwood Springs, Joshua Tree National Park, San Bernardino Co., CA. 4-23-06. © Joan Avise.	Rice Canyon, E Santa Ana Mts., 7-5-12. © Ron Vanderhoff
Horseshoe Bend, S.A. River, 9-1-11. © Ron Vanderhoff	Rice Canyon, E Santa Ana Mts., 7-5-12. © Ron Vanderhoff
Rice Canyon, E Santa Ana Mts., 7-5-12. © Ron Vanderhoff	Modjeska-Santiago Cyn, 12-2-10. © Ron Vanderhoff
Female catkins. San Joaquin Wildlife Sanctuary, Irvine, CA. 4-16-11. © Joan Avise.	Female catkin. San Joaquin Wildlife Sanctuary, Irvine, CA. 4-16-11. © Joan Avise.
Female flower. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Female flower. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant	Female flower. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Female catkins with developing fruit. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant	Female catkins with developing fruit. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Male catkin. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant	Male catkin. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Male catkin. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant	Male catkins. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Male catkins. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant	Male catkins. San Joaquin Wildlife Sanctuary, Irvine, CA. 3-31-13. © Peter J. Bryant
Developing fruit. San Joaquin Wildlife Sanctuary, Irvine, CA. 5-19-07. © Joan Avise.	Developing fruit, Big Morongo Canyon Preserve, San Bernardino Co., CA. 3-23-08. © Joan Avise.
Unidentified galls. San Mateo campground, Orange County, CA. 5/29/12. © Peter J. Bryant	Unidentified galls. San Mateo campground, Orange County, CA. 5/29/12. © Peter J. Bryant
Populus trichocarpa L, fremontii R, Santa Ana River, N side, at Gypsum Cyn. Rd., 9-8-13. © Ron Vanderhoff
Associated Insects
Poplar Petiole Gall induced by Pemphigus populicaulis	Poplar Petiole Gall Aphid, Pemphigus populicaulis
	Unidentified aphid on Fremont Cottonwood
	Unidentified aphid on Fremont Cottonwood