The purpose of this study was to investigate the requirements for embryo growth and germination in seeds of Angelica tomentosa var. hendersonii, A. triquinata, and A. venenosa. Angelica venenosa and A. triquinata are eastern North American species, and A. tomentosa is a coastal species of Oregon and California. Embryos in freshly matured seeds of A. tomentosa and A. venenosa grew during cold stratification (5/1 oC), and seeds germinated after they were transferred to alternating temperature regimes of 15/6, 20/10, and 25/15 oC following 3, 6, 9, and 12 wk of cold stratification. Optimal germination temperature for both species was 15/6 oC, and cumulative germination percentages increased with cold stratification. Thus, seeds of A. tomentosa and A. triquinata have deep complex morphophysiological dormancy (MPD). Embryo growth in A. triquinata occurred during warm stratification (25/15 oC), and after 2 wk of incubation at 25/15 oC 24 ± 1% of the seeds had germinated. Like A. tomentosa and A. venenosa, germination of A. triquinata increased with cold stratification, but the optimum germination temperature for the latter species was 25/15 oC. Thus, a portion of the seed population of A. triquinata was morphologically dormant, while the remainder had nondeep simple MPD. The eastern-western North American disjunct genera Osmorhiza and Erythronium are represented by species with different levels of MPD (C. Baskin, et al., Am. J. Bot. 82: 293-298, 1995). In contrast, the present study shows that the western vs. eastern North American species of Angelica may (A. tomentosa ¹ A. triquinata) or may not (A. tomentosa = A. venenosa) differ in its level of MPD.

Key words: Angelica, Apiaceae, Arcto-Tertiary, disjunct species, seed dormancy