Variability in Cuphea viscosissima Jacq. collected in east-central United States

Abstract

Accessions of Cuphea viscosissima were collected from the central and east-central U.S. during two field explorations, one in 1987 and the other in 1989. Characterization and evaluation data of accessions collected in 1987 have been reported earlier. This paper reports the results of characterization and evaluation trials of the 1989 collections. Thirty-one of these accessions were grown for characterization and seed-increase plantings in 1990 and twenty-four of these in replicated evaluation trials in 1991 at Ames, Iowa. Morphological characters are rather uniform and resemble accessions collected in 1987. A new pale flowered form was identified. Glandular trichomes, which produce a sticky resin, occurred uniformly on the stems and flowers of all accessions, but their presence on leaves was variable. Fourteen of the thirty-one accessions lacked glandular trichomes on their leaves. Statistically significant variation occurred in plant height (59 to 90 cm) and mass (89 to 216 g), seed yield (0.9 to 7.0 g/plant), and the amounts of caprylic (8:0) (14.3 to 16.8%), capric (10:0) (68.0 to 71.9%), and lauric (12:0) (2.5 to 3.4%) acids. Variations in 100-seed weight, seed germination, and oil content were non-significant. The narrow range of variability found in these accessions collected from rather diverse ecological regions would suggest that C. viscosissima has occupied its native range rather recently, and has had little time to diversify genetically. The variability identified is being used in interspecific hybrid crosses with C. lanceolata Aiton to develop a domestic source of medium-chain fatty acids.