Narrow hybrid zone between two subspecies of big sagebrush, Artemisia tridentata (Asteraceae). VIII. Spatial and temporal pattern of terpenes

Parental and hybrid populations of big sagebrush in Salt Creek Canyon, Utah , show clinal variation in terpene composition across a hybrid zone. Terpen es differ between seasons, subspecies (including hybrids), individual plant s, and leaves from vegetative branches and inflorescences on the same plant . While hybrids were intermediate for most common terpenes, several terpene s produced by both parental taxa were not produced by hybrids. Furthermore, hybrids produced novel terpenes. The clinal variation of terpenes is highl y correlated with both morphological variation and edaphic gradients. (C) 1 998 Elsevier Science Ltd. All rights reserved.