Comparing the germination, growth, and morphology of native Canadian and commercially sourced seeds of wood-poppy (Stylophorum diphyllum)

Abstract

The wood-poppy (Stylophorum diphyllum (Michaux) Nuttall [Papaveraceae]) is listed as endangered under Canada’s Species at Risk Act. Five extant populations are in Canada. One potential recovery strategy for S. diphyllum is to augment existing populations and (or) establish new populations via conservation translocation. While seeds are sold in the nursery trade, few studies have been published on ex situ germination and propagation. Predictions are that Canadian populations are genetically distinct from US populations, but no studies have tested for phenotypic differences between plants from these sources. We collected, stratified, and sowed seeds from 2 of the native Canadian populations and 3 commercial seed companies and grew them in a common garden. We achieved a germination rate of 53% for seed from Canadian populations and 44% for commercial seeds following 2 mo stratification at 25 °C (77 °F) and 2 mo at 4 °C (39 °F). Plants from 1 Canadian population grew faster, produced more leaves, differed in leaf and seed morphology, and had fewer trichomes than the plants of commercial origin. These results show that S. diphyllum can be propagated successfully from Canadian seed sources and that Canadian S. diphyllum populations are likely phenotypically distinct from commercial stock. Our findings will inform the development of a translocation strategy and set the stage for genetic analysis of these populations.