Seed germination in Viola pedunculata and Viola purpurea subsp. quercetorum (Violaceae), critical food plants for two rare butterflies

ORCID

Dr. Ryan Hill: 0000-0001-8513-6545

Document Type

Article

Publication Title

Madroño

Department

Biological Sciences

ISSN

0024-9637

Volume

64

Issue

1

DOI

10.3120/0024-9637-64.1.43

First Page

43

Last Page

50

Publication Date

1-1-2017

Abstract

Viola L. are the larval food plants for a charismatic group of butterflies in Speyeria Scudder, 1872, which contains several rare and declining taxa in California and across North America. A current impediment to restoring Viola in California is a lack of knowledge of germination requirements. In this study we focused on determining conditions for successful germination of V. pedunculata Torr. & A. Gray, the food plant of the federally listed endangered Speyeria callippe (Boisduval, 1852) subsp. callippe, and V. purpurea Kellogg subsp. quercetorum (M.S. Baker & J.C. Clausen) R.J. Little, the food plant of the imperiled southern Coast Range butterfly, S. adiaste (Edwards, 1864) subsp. clemencei (Comstock, 1925). We examined the effects of gibberellic acid, seed color, elaiosome removal, and duration of stratification on germination success. We found that both taxa germinate exceptionally well (73–100%) after a prolonged period of after-ripening and 6–10 wk of stratification. Gibberellic acid and elaiosome removal did not have strong effects on germination of V. pedunculata, and both dark and mottled V. purpurea subsp. quercetorum seeds germinated equally well. We make recommendations for successful lab germination of these two native violets, setting the stage for additional research to help restore their populations as well as their herbivores.

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