Various workers have postulated that members of Physalis section Lanceolatae naturally hybridize. Successful artificial hybridizations have been accomplished, but documented cases of natural hybridization are rare. In areas of sympatry, different habitat preferences help keep species of the Lanceolatae separated. In north Florida, however, populations of P. arenicola and an undescribed species of the Lanceolatae co-occur along the bluffs of the Apalachicola river. This provides a unique opportunity to address the question of natural hybridization among species of the Lanceolatae. Physalis arenicola occurs throughout Florida, favoring sandy, open areas. The undescribed species grows on wooded river bluffs, and is apparently limited to a two county region. Vegetatively, these taxa are quite similar, though P. arenicola encompasses a broader range of morphological variation. The two taxa are best distinguished by differences in rhizome morphology. Is the vegetative similarity between these species due to the fact that they are closely related and still share plesiomorphic characters, or is there some gene flow between them? Leaf material was collected from multiple individuals in the mixed species populations, and from isolated populations of each taxon, including individuals of P. arenicola from southern Florida, where the river bluff taxon does not occur. Isozyme data was generated using the following 12 enzyme systems: ACO, ALD, GDH, G3PDH, IDH, MDH, ME, PGI, PGM, PRX, SKD, and TPI. Within P. arenicola, ACO, GDH, ME, PGI, PRX and TPI are polymorphic. IDH is variable within both species. IDH also shows species specific variation, as do MDH and SKD. Each species has a unique ITS sequence. Eight characters differentiate these sequences, including an 8 bp indel. The amount of ITS sequence variation between these species is similar to that between sequences of other closely related species within the Lanceolatae.

Key words: Florida, hybrid, isozyme, Physalis, Solanaceae, sympatry