June 28, 2016
Today, our collection efforts were focused on the Oglala National Grassland in northwestern Nebraska and the Buffalo Gap National Grassland in southwestern South Dakota. These short to mixed grasslands occur on “badlands” soils. Badlands are arid land formations where soft, sedimentary rocks have been extensively eroded by wind and water resulting in clay-rich soils. A wide range of tough, beautiful plants thrive in spite of these harsh conditions, including Calylophus serrulatus (dwarf sundrops). From a horticultural standpoint, many broadly distributed species found throughout the U.S. occur in these grasslands, allowing us to make selections for stress and drought tolerance in the landscape. We collected a heavily fruited form of Rhus aromatica (aromatic sumac), which often gets planted in medians and along highways for its rugged durability.
Seasonal droughts in recent years have limited the vigor of these environments, so our collections were accordingly sparse. We had the opportunity to view many diverse plant communities that could serve as model systems for horticulture in the future, including many Nassella viridula (green needlegrass) meadows. This species is a cool season bunchgrass that thrives in dry conditions, flowers early in summer and turns golden yellow in autumn. Dotted among these meadows, many plains prickly pear cactus were flowering in various shades of yellow, pink and orange. We made several color selections for future evaluation and inclusion in the conifer and gravel garden. Late in the afternoon, a prairie thunderstorm rolled through the Buffalo Gap and for a brief while, we were stuck in the middle of county road that turned very quickly from modest gravel and reasonably passable to muddy and impassable. A little Eagle Scout maneuvering by curatorial horticulturist Winston Beck took us out a drainage ditch (drier than the road, actually) and had us on our way to a small hot springs south of Hot Springs, SD. In this unique location, a small population of Adiantum capillus-veneris (southern maidenhair fern) grows alongside a creek sprayed by the mineral-rich water babbling through the stream. Many gardeners grow this as a houseplant, but this population somehow braves South Dakota winters as one of the northernmost disjuncts from the rest of the species range (which occurs all the way into South America). Plants are fascinating!