Data from: Cracking the case: seed traits and phylogeny predict time to germination in prairie restoration species

1. Traits are important for understanding how plant communities assemble and function, providing a common currency for studying ecological processes across species, locations, and habitat types. However, most studies relating species traits to community assembly rely upon vegetative traits of mature plants. Seed traits, which are understudied relative to whole-plant traits, are key to understanding assembly of plant communities. This is particularly true in restored communities, which are typically started from seed, making germination a critical first step in community assembly. 2. We experimentally tested effects of seed traits (mass, shape, and embryo to seed size ratio) and phylogeny on germination in 32 species commonly used in prairie restoration in the Midwestern USA, analyzing data using time-to-event (survival) analysis. Since germination is influenced by seed dormancy, and dormancy-break treatments are commonly employed in restoration, we also tested the effects of two pre-treatments (cold stratification and gibberellic acid application) on time to germination. 3. Seed traits, phylogenetic position and seed pre-treatments affected time to germination. Of all traits tested, variables related to seed shape (height and shape variance) best predicted germination response, with high-variance (i.e., narrower) seeds germinating faster. Phylogenetic position (location of species on the phylogenetic tree relative to other tested species) was also an important predictor of germination. Closely related species showed similar patterns in time to germination. This was true even though all measured traits showed phylogenetic signal. 4. Seed traits, phylogenetic position and germination pre-treatments were important predictors of germination response for species commonly used in grassland restoration. Shape traits were especially important, while mass, often the only seed trait used to study community assembly, was not a strong predictor of germination timing. These findings illustrate the ecological importance of seed traits that are rarely studied in plant communities. This information can also be used to guide restoration planning and seed mix design