Experimental Design
We selected two natural D. californica populations located outside of Eugene, Oregon as common garden sites for our experiment. The first common garden, Hazel Dell (hereafter HD; N44.01979, W123.21823, 157 masl), is a seasonal wet prairie at the southern end of the Willamette Valley (Appendix A; C). The second common garden, Horse Rock Ridge (hereafter HR; N44.29877, W122.87984, 570 masl), is an exposed ridgeline in the Coburg Hills (Appendix A; D), which are foothills of the Cascade Mountains. While these two sites are geographically close relative to the entire latitudinal range from which we sourced seeds (Fig. 1A), they represent very different ecological extremes at approximately the same latitude: HD being a mesic, deep soil, low elevation site (Appendix A; C), and HR being a steep slope with dry, shallow soil, and higher elevation site (Appendix A; D).
In June and July 2018, we collected approximately 50,000 cleistogamous and chasmogamous seeds (approximately 25,000 each) from natural D. californica populations at our two common garden sites and six other sites in the greater Klamath Mountain - Willamette Valley - Puget Lowland ecoregions (Fig. 1A). Both seed types were collected from each maternal plant; both occur on the same reproductive stems. We collected 5-10 reproductive stems from each of 11-21 large maternal plants (median = 15) at each population.