Sherwin John Carlquist FMLS (born 7 July 1930) is an American botanist and photographer. He received his undergraduate degree from the University of California, Berkeley in 1952 and a Ph.D. in botany in 1956, also at Berkeley. Carlquist did a postdoctoral study at Harvard University from 1955 to 1956. After his postdoctoral studies, he began his teaching career at the Claremont Graduate School. In 1977 he also began teaching at Pomona College and continued teaching at both institutions until 1992. From 1984 to 1992 Carlquist as the resident Plant Anatomist at Rancho Santa Ana Botanic Garden. His last post was as an adjunct professor at University of California at Santa Barbara from 1993 to 1998.
Carlquist studied wood anatomy of the Gnetophyta and was an author of many plant taxa, including species of the carnivorous plant genus Drosera, the Western Australian genus Stylidium, and the odd Australian genus Alexgeorgea whose female flowers are almost entirely underground.
The California plant genus Carlquistia is named for Carlquist.