There are over 1,500 plant species in South Dakota, and of those, over 1,200 species can be found in the Black Hills. The ponderosa pine is the dominant tree found in the Black Hills, and it is found in every region and habitat in the hills. Companion vegetation, however, is dictated by variations in moisture, elevation, temperature, and soil conditions. Species common to prairie grasslands, coniferous forest, deciduous forest, and mountainous forests can all be found in the region. It is estimated that of the 1,200 species of plants found in the Black Hills Region, 30 percent originated in the Plains, 25 percent in the Rockies, 5 percent in deciduous forests, and 1 percent in northern forests.
Wind Cave National Park, the Badlands, and the southern area of Custer State Park contain both ponderosa pine forest and mixed-grass prairie environments. In yet another example of how east meets west in the Black Hills, the area west of the Black Hills is short-grass prairie and east of the Missouri, the prairie lands are tallgrass prairie. Plants that grow in short-grass prairie or in tallgrass prairies can both be found in the mixed-grass prairie of western and central South Dakota. In a rainy year, tallgrass prairie plants will be the most evident. In an arid year, the short-grass prairie plants will thrive. Tallgrass prairie plants require more moisture than short-grass plants and can usually be located, even in dry years, in valleys, where drainage will add moisture to the fields.
Cactus plants thrive in short-grass prairies and prickly pear and pincushion cactus are common in this region on the drier southern-facing slopes. Other common shortgrasses in this area include bluegrasses, buffalo grass, wheatgrass, and little bluestem. Shrubs include rabbitbrush, sage, mountain mahogany, buffaloberry, dogwood, snowberry, and coralberry among others.
About 25 percent of Wind Cave is tree-covered; ponderosa pine is the most common tree. There are also scattered groves of elm, aspen, bur oak, box elder, and birch in the park, which are usually found in drainage areas.
A deciduous tree is one that sheds its leaves in the winter, enters a dormancy phase in cold weather, and then, when warmer temperatures return, experiences re-growth. This process allows the tree to withstand extremes of temperature. There are several pockets of deciduous trees in the hills, most of which are migrants from the east. On the eastern side of the hills near streambeds, deciduous trees include the box elder, ash, American elm, eastern cottonwood, dogwood, and willow trees. The northeastern foothills, at lower elevations and with relatively dry slopes, host bur oak trees with an understory (plants that grow in the shade or beneath the canopy of higher trees) of sumac, coralberry, and poison ivy. In the northwest corner of the hills, quaking aspen and paper birch trees can be found. Understory plants include chokecherry, beaked hazelnut, and wild rose.
Ponderosa pine is found everywhere in the Black Hills. There are regional variations in the understory of the forest depending on many factors, including moisture levels, temperature, and elevation. In the Southern Hills, where the environment is generally warmer and drier than the rest of the hills, the understory of the ponderosa pine forest is comprised of little bluestem, yucca, sagebrush, sand lily, and various gramas and needlegrasses. In areas that are at elevations over 7,000 feet, the understory is comprised of juniper, Oregon grape, buffaloberry, and blue wild rye. At the moister elevations of 4,000–5,000 feet, the forest canopy includes both the ponderosa pine and the bur oak, with an understory of chokecherry, Oregon grape, and melic grasses. On the western edge of the hills, skunkbrush and American black currant appear. White spruce is also found in the higher and moisture-rich elevations of the Black Hills. A variant of the white spruce, the Black Hills spruce is the state tree of South Dakota.
At first glance, the prairie grasslands look to be a sea of soft green or gold, depending on the season. A closer look reveals bright vibrant color scattered throughout the fields. There are literally hundreds of wildflower species that grow in the prairie grasslands. The pasque flower, a beautiful light violet flower, is one of the first flowers of early spring and is the state flower. Many species of milk vetches, asters, milkweeds, penstemons, and evening primroses are common.
Beautiful to look at, flowers in the Black Hills were also used for practical and medicinal purposes by many Native Americans. The sap of the bright yellow false dandelion was used to clean teeth; wild blue flax seeds were used to flavor food, purple clover made a flavorful tea; the purple coneflower (Echinacea) was used for headaches, stomachaches, and sore throats.
© Laural A. Bidwell from Moon Mount Rushmore & the Black Hills, 1st Edition