In his 1500 California Place Names (1998), William Bright writes that the name is Spanish for "where the chual grows," chual being Mexican Spanish for pigweed or goosefoot, and derived ultimately from Nahuatl tzoalli.
These weed species include Solanum nigrum (nightshade), S. aculeatissimum (soda apple), Chenopodium album (pigweed), Datura stramonium (jimson weed), Linaria canadensis (blue toadflax), and Physalis spp.
Amaranthus cannabinus - salt-marsh water-hemp, tidal-marsh water-hemp or water-hemp pigweed