Seed Germination in the Riparian Zone: The Case of the Rare Shrub, Spiraea virginiana (Rosaceae)


Jessica R. Brzyski

Additional Authors:

Theresa M. Culley,


June 2013


Clonal, conservation, rare, restoration, seed germination, Spiraea virginiana

ABSTRACT Conservation of rare species often involves restoration efforts to enhance or expand existing populations, a critical step of which is seed germination. Seed germination can be especially problematic in riparian zones where habitat disturbance through flooding can be a regular and frequent event. Spiraea virginiana Britton, a riparian clonal shrub, is a rare species that is particularly susceptible to problems at the seed stage; it is generally assumed to lack effective seed recruitment, although seeds are sometimes observed in the field. Therefore, we examined the effects of growth substrate and cold stratification on the number of days required for seeds to germinate and overall seed germination success. Overall, total seed germination for S. virginiana was low at only 10% and cold stratification had a significant effect on the initiation of germination; as the number of days of cold stratification increased, the time necessary for seeds to germinate decreased. Although seedlings of S. virginiana have not been observed in nature, this study indicates that seeds can germinate and thus recruitment by seed is at least theoretically possible. We recommend that a seed germination protocol using sterile soil with cold (58C), stratification treatment of at least 30 d should be used in future propagation and restoration efforts.