Date of this Version
HORTSCIENCE 25(4):489. 1990
‘Prairie Snow’ is a white-flowered, seedpropagated bulk population of Penstemon grandiflorus selected for home landscape use that also can be used for prairie and roadside plantings. It was released in 1988 in conjunction with, and to honor, the 10th anniversary of the Nebraska Statewide Arboretum. It is unique to this species because of its pure white flowers. A native population of P. grandiflorus was manipulated using a modified bulk population selection scheme so that plants with specific traits could be isolated from plants without the desired traits.
Two similar cultivars, Albus and Lena Seeba, have been mentioned in the literature. The source of the P. grandiflorus ‘Albus’ listing in Hortus Third (Liberty Hyde Bailey Hortorium, 1976) was based on a catalogue listing in the late 1940s (E. Koop, Liberty Hyde Bailey Hortorium, personal communication). Another reference, however, lists ‘Albus’ as P. fruticosus (Peterson, 1984). The cultivar Lena Seeba is listed as a hybrid of “P. grandiflorus (white) × unknown peltantera species” in the American Penstemon Society Cultivar Registry (D.T.L, personal communication). Neither cultivar is currently available.
P. grandiflorus, commonly known as the shell-leaf penstemon, is endemic from North Dakota to Texas and from Wyoming to Illinois (Gleason, 1952). Native populations are generally pink- or lavender-flowered with a low percentage of white-flowered plants. Observations of native populations indicate that <1% of the plants are white-flowered.
Seeds collected near Dunning, Neb., from a population of pink-flowered P. grandiflorus plants containing one white-flowered plant were cold-stratified for 8 weeks at 1C, then placed in a greenhouse and germinated. Plants were transplanted to field plots and observed for flower color. There was a strong correlation between stem color and flower color, as plants with nonpigmented stems produced white flowers and plants with pigmented stems produced pink or lavender flowers. Plants with white flowers displayed no reddish stem/leaf pigmentation. Further observations indicated that newly emerged seedlings grown in the greenhouse also exhibited either reddish pigmentation in hypocotyls and leaves or no apparent pigmentation. Seedlings in the greenhouse with no red pigmentation were transplanted to field plots 0.5 km from other P. grandiflorus plants. About 95% of these plants were white-flowered, while the remainder were pink. The pink-flowered plants were rogued out before pollen release, leaving only white-flowered plants in the population. Seeds were collected from these whiteflowered plants and planted. Of these seedlings, 95% were white-flowered, with the remaining plants flowering a very light pink. A follow-up study using seed from the whiteflowered plants in the previous study indicated that >99% of the seedlings were whiteflowered. These white-flowered plants were used as a source of seed for the ‘Prairie Snow’ bulk population. Future generations of ‘Prairie Snow’ will continue to be reselected for the desired trait.