Shattercanes (sorghum plants with deciduous sessile spikelets) from the midwestern United States were compared with cultivated sorghum (S. bicolor), sudan grass (S.bicolor var. sudanense), johnson grass (Sorghum halepense), sorghum almum (Sorghum x almum), known hybrids between these taxa, and offtypes in fields of cultivated sorghum in terms of morphology and isozyme patterns. Statistical analyses of morphological data suggest a near-continuum between forms; isozyme data was singularly uninformative in this group. Further, shattercanes are of two types: those that form an abscission callus, and those with a fragile rachis. Many offtypes that exhibit the common morphological characteristics of midwestern shattercanes but do not shatter are also found in and near farm field. It is concluded that "shattercanes" are polyphyletic; that some originated as hybrids or as segregants of hybrids between various taxa of Sorghum, and that others are derivatives of cultivated sorghum that mimic wild types.