Plant Materials
Silphium integrifolium seeds were collected from 12 prairies in 2017 and 2018 (Figure 1; Table 1). The prairie remnants collected spanned from central Kansas to central Illinois. The prairie remnants have variable historical, geographic, and climatic characteristics described in Cassetta et al 2023. From each of the 12 prairies, seeds were collected from approximately 40 mother plants randomly chosen from throughout the prairie remnant. As S. integrifolium is an obligate outcrosser, seeds collected from a single mother were a half sibling family.
S. integrifolium seeds were germinated at room temperature together in a heated greenhouse at The Land Institute, Salina KS in 2019. A total of 96 genets comprising eight individuals from each prairie remnant from different mothers were selected from the seedlings. Selection of the 96 individuals was randomized although the seedlings chosen had to be moderately vigorous. The pots containing the seedlings were randomized and placed on greenhouse benches. Pots were re-randomized several times during the season. The plants grew rapidly but remained as vegetative rosettes. Each crown (genet) was divided into 4 pieces (ramets) with approximately equal numbers of dormant buds and roots, although a few crowns were too small and only produced 2-3 pieces. The ramets were repotted into 10-gallon fabric planters (Smart Pot) using Pro-Mix BX.