The case of the curious 'Cannabis'

In a recent paper in Economic Botany, Quimby et al. (1973) described a peculiar variant of Cannabis, found on a herbarium sheet housed in the Field Museum of Natural History, Chicago, Illinois (accession number 1628511). This specimen was identified on the herbarium label as Cannabis indica Lam., and Quimby et al. interpreted it as an unusual example of Cannabis sativa L., with pinnate leaves. Two photographs of this specimen were included in the paper '(figs. 23, 24, p. 127; not fig. 22 as stated in text). The specimen has been cited several times in recent symposia, and I have received a number of inquiries concerning its nature. Dr. John McNeill of this institute and I have determined that the plant in question is in fact a male of Datisca cannabina L. Male plants of Datisca cannabina L. are remarkable mimics of Cannabis sativa L. (females are less so). As noted by Steam (1974): "In the Hortus Cliffortianus, Linnaeus provided a short diagnosis, Cannabis foliis digitatis, to distinguish the true hemp from a then imperfectly known plant diagnosed there as Cannabis foliis pinnatis, but named Datisca cannabina in the first edition of the Species Plantarum." On close examination, a wealth of characters distinguish the two species. Indeed, they are so distant that Cronquist (1968) assigns