Seed type and origin‐dependent seedling emergence patterns in Danthonia californica, a species commonly used in grassland restoration

• Published in: Plant-environment interactions (Hoboken, N.J. : 2018) N.J. : 2018), 2023-04, Vol.4 (2), p.97-113
• Main Authors: Jones, S. Holden, Reed, Paul B., Roy, Bitty A., Morris, William F., DeMarche, Megan L.
• Format: Article
• Language: English
• Subjects: Adaptation; climate warming; common garden; Danthonia californica; Ecosystems; Environmental conditions; Environmental restoration; Flowers & plants; Gardens & gardening; Genetic diversity; Grasslands; local adaptation; nonlocal; Plant populations; Populations; Restoration; Seedlings; Seeds
• ISSN: 2575-6265; 2575-6265
• DOI: 10.1002/pei3.10105

Danthonia californica Bolander (Poaceae)is a native perennial bunchgrass commonly used in the restoration of prairie ecosystems in the western United States. Plants of this species simultaneously produce both chasmogamous (potentially outcrossed) and cleistogamous (obligately self‐fertilized) seeds. Restoration practitioners almost exclusively use chasmogamous seeds for outplanting, which are predicted to perform better in novel environments due to their greater genetic diversity. Meanwhile, cleistogamous seeds may exhibit greater local adaptation to the conditions in which the maternal plant exists. We performed a common garden experiment at two sites in the Willamette Valley, Oregon, to assess the influence of seed type and source population (eight populations from a latitudinal gradient) on seedling emergence and found no evidence of local adaptation for either seed type. Cleistogamous seeds outperformed chasmogamous seeds, regardless of whether seeds were sourced directly from the common gardens (local seeds) or other populations (nonlocal seeds). Furthermore, average seed weight had a strong positive effect on seedling emergence, despite the fact that chasmogamous seeds had significantly greater mass than cleistogamous seeds. At one common garden, we observed that seeds of both types sourced from north of our planting site performed significantly better than local or southern‐sourced seeds. We also found a significant seed type and distance‐dependent interaction, with cleistogamous seedling emergence peaking approximately 125 km from the garden. These results suggest that cleistogamous seeds should be considered for greater use in D. californica restoration. We did not find any evidence for local adaptation in a common garden study using both cleistogamous and chasmogamous seeds of Danthonia californica, a bunchgrass species commonly used in restoration outplanting. We found that cleistogamous seeds significantly outperformed chasmogamous seeds and that northern seeds outperformed sourthern seeds. Our results and methods suggest that cleistogamous seeds should be considered for more frequent use in D. californica restoration.