Naturalized from Europe and generally considered a weed, sowthistle is
found in waste grounds and along roadsides from near sea level to 8,000
feet. It blossoms from February to August, the flowers becoming cottony
seed heads as conspicuous as the blooms. A close relative, _Sonchus
oleraceus_, which blossoms from March to September, produces a gum from
the drying of the sap, reportedly a powerful cathartic. It has also been
used as a treatment for persons suffering from the habitual use of opium
derivatives.
_Sonchus asper_ Sunflower Family
[Illustration: PRICKLY SOWTHISTLE]
_Suggestions for Additional Reading_
Armstrong, Margaret, _Field Book of Western Wild Flowers_, C. P.
Putnam’s Sons, New York, 1915.
Benson, Lyman, _The Cacti of Arizona_, University of Arizona Press,
Tucson, 1950.
Benson, Lyman, and Darrow, Robert, _The Trees and Shrubs of the
Southwestern Deserts_, University of New Mexico Press, Albuquerque,
N.M., 1954.
Dodge, Natt, _Flowers of the Southwest Deserts_, Southwestern
Monuments Association, Globe, Arizona, 1951.
Hornaday, W. T., _Camp-fires on Desert and Lava_, Charles Scribner’s
Sons, New York, 1909.
Jaeger, Edmund C., _Desert Wild Flowers_, Stanford University Press,
Stanford, California, 1956.
Jaeger, Edmund C., _The North American Deserts_, Stanford University
Press, Stanford, California, 1957.
Lemmon, Robert S., and Johnson, Charles C., _Wildflowers of North
America in Full Color_, Hanover House, Garden City, N.Y., 1961.
Leopold, A. Starker, _The Desert_, (Life Nature Library) Time Inc.,
New York, 1961.
McDougall, W. B., and Sperry, Omer E., _Plants of Big Bend National
Park_, Government Printing Office, Washington, D.C., 1951.
Shreve, Forrest, and Wiggins, Ira L., _Vegetation and Flora of the
Sonora Desert_, Carnegie Institution of Washington Publication No.
591, Vol. 1, Washington, D.C., 1951.
Vines, Robert A., _Trees, Shrubs, and Woody Vines of the Southwest_,
University of Texas Press, Austin, 1960.