The common field horsetail, Equisetum arvense L., as is well known, produces in early spring fertile shoots almost destitute of chlorophyll. After shedding their spores, these quickly wither and are succeeded by the sterile, branched, vegetative shoots which persist until late autumn. Early in May, 1943, Mr. George Coffey, then a graduate student in botany in the State University, brought into the laboratory a shoot of what appeared to be this species with a green stem and whorls of green branches, but tipped by a small, but perfectly formed strobilus. It had been collected in a slough on the west side of the Iowa River within the city limits of Iowa City. Mr. Coffey revisited the locality in an attempt to find other similar shoots but was unsuccessful.
Proceedings of the Iowa Academy of Science
©1946 Iowa Academy of Science, Inc.
Martin, G. W.
"Fertile Green Shoots of Equisetum Arvense,"
Proceedings of the Iowa Academy of Science, 53(1), 157-169.
Available at: https://scholarworks.uni.edu/pias/vol53/iss1/17