Harperella (Ptilimnium nodosum)
September 28, 1988
For more information on Harperella, contact Rebecca Peak at firstname.lastname@example.org or 501-513-4475.
Harperella is an annual herb in the carrot family that grows from 6 to 36 inches tall. The leaves are reduced to hollow, quill-like structures. It blooms in midsummer with inconspicuous white flower clusters similar to those of Queen Anne's lace, which last until the first frost.
Harperella can reproduce in two ways; by seed, which drop in late summer, or by ramets (small clones) that grow on the stem of the parent plant. Both seeds and ramets can drop off the parent plant and root nearby, or can be carried away to potential habitat during minor flooding. They germinate by early fall and, if they survive the winter, develop into mature plants the next spring.
Harperella is found only on sunny, rocky or gravel shoals and margins of clear, swift‐flowing stream sections in the Ouachita Mountains. It requires very specific conditions; shade, dry spells, too much heat, soft soil, extended periods of deep water, heavy flooding, grazing, and trampling can all quickly destroy a population.
Why is it Endangered?
Erosion leading to sedimentation of stream channels is the primary threat to the continued existence of this species. Since Harperella requires a narrow range of water depths, altered hydrology and water flow from the construction of dams and increased runoff has also greatly affected this species.
Harperella populations fluctuate wildly between years, making it hard to estimate population size and trends. Although harperella plants have been grown in laboratory settings, transplantations in the northeastern portion of it's range have not had much success.
Range in Arkansas: