Opuntia polyacantha,, Phemeranthus parviflorus, Artemisia frigida, Symphiotrichum laeve var. geyeri, and Leucocrinum montanum

I've been intrigued by these guys ever since they appeared in the greenhouse; they are the plants that Scott, Kevin, and GrayC collected in South Dakota. The bulk of their collections were seeds so these are just a taste of what's to come. They collected in areas that experience extremes of heat and cold far beyond the norms of our area combined with low rainfall, and, as I understand it, some humidity in the summer. Potentially some of these plants could be added to the palette of green roof plants. Many of us are concerned that green roofs have become monocultures of sedums and iceplants. The roofs would be more interesting and attractive with more diverse planting, and monocultures make us all uneasy. While some green roofs are out of sight, others are highly visible to the point that they become roof gardens. In those gardens diversity of form, color, texture, and bloom is important.

Leucocrinum montanum, Sand Lily, (the empty pots in the last picture)  is a pretty exciting plant. It's dormant now but puts up grassy foliage in the spring and 2" white flowers in late-spring/early-summer.  Phemeranthus parviflorus, Prairie Fameflower, is my kind of plant; it's a tough tuft that blooma with an abundance of smallish pink flowers. The first plants I grew were desert plants and I'm still drawn to plants that can hold their own against adversity.

I've been working on a list of North American natives that could be useful roof garden or green roof plants. I'm happy to see Opuntia polyacanth in their collections. It's one of the most widely distributed prairie Opuntias and a beautiful cactus. In the east, we're used to O. humifusa, which is an attractive and tough. enough plant but lacks the beautiful spination and upright habit of O. polyacantha.The Aster, Symphiotrichum laeve var. geyeri is maybe not a roof garden plant but still beautiful and tough.  Artemisia frigida, Prairie Sagewort, is a smallish Sagebrush with silvery aromatic foliage. That would be cool in a roof garden! There are some exciting plants I didn't photograph including a dwarf xeric clematis with full sized flowers.