The U.S. Forest Service (USFS) defines rare plants as any plant species that is either restricted to one specific geographic location, or if only a few of the plants exist. The rarest plants fulfill both categories, meaning there are only a few individual plants in existence and they are all located in one geographic region. Some plants are naturally rare. However, others begin to decline due to habitat loss, loss of pollinators, excess harvesting, or the introduction of competitors, pathogens or pests. Conservationists are constantly on the lookout for rare plants and ways to improve their chance of future survival. Gardeners and homeowners can get in on the action by learning about rare plants.
The Capa rose (Callicarpa ampla) is a flowering shrub which the Forest Service classified as endangered in 1992. This plant features broad green foliage, small purple flowers and dark-purple berries. The Capa rose can be found in the woodlands of Puerto Rico, with the largest numbers growing in the El Yunque National Forest. According to the USFS, this plant is threatened by forest management practices, trail maintenance, construction of roads and communication facilities, as well as collection and hurricanes.
The smooth coneflower (Echinacea laevigata) is a perennial herb in the Aster family. This endangered plant, similar to the purple coneflower, is found sporadically throughout the eastern regions of Virginia, North and South Carolina, as well as Georgia. According to North Carolina Ecological Services, "smooth coneflower is threatened by fire suppression and habitat destruction resulting from highway construction, residential and commercial development, as well as maintenance activities in roadside and utility right of way. Collection from the wild for horticultural and medicinal uses could also threaten smooth coneflower."
The Ohio Department of Natural Resources lists wild calla (Calla Palustris L.) as an endangered low-growing perennial herb. These plants are found in Maryland, Indiana and Iowa. The plants feature small yellow flowers covered by white spathes which resemble peace lilies. These flowers used to flourish in bogs, pond margins and swamp forests. However, due to over-shading by woody plants as well as habitat destruction due to draining, filling and peat mining, these flowers have become sparse.