Plant of the Week
Cut-leaved Toothwort (Cardamine concatenata)
By Chris Mattrick, White Mountain National Forest Botanist
Members of the mustard family (Brassicaceae) are widely known for their taste, utility, and ability to become weedy, but rarely for their beauty. In the case of the cut-leaved toothwort (Cardamine concatenata) however, its beauty is as great as it is fleeting. As a true ephemeral species (a species appearing only briefly aboveground to reproduce and then go dormant) its entire growth and reproductive cycle lasts little more than one month. It is a spring ephemeral appearing in late April or early May in northern climates, and somewhat earlier in southern areas. It is native to every state east of the Rocky Mountains and is common in most areas. Only in the most northeastern state is the species considered endangered with only one known population in Maine and three in New Hampshire.
This perennial species occurs in rich deciduous forests and wooded slopes where there is a deep cover of leaf litter and soils high in organic matter. A single stem rises from 8 to 15 inches from a slender, segmented rhizome. The leaves appear in whorls of three. Each leaf is dissected and coarsely toothed. The dissection, size, and arrangement of teeth on the leaf segment margins are highly variable both within and among populations of this species. The flowers are white, (sometimes pink especially in bud) and arranged in a terminal cluster. Each flower is approximately three-quarter inch across. The small black seeds are contained in a long erect pod.
Cut-leaved toothwort is easily distinguished from other members of the genus in northeastern states by its highly dissected and toothed leaves. Throughout the south and central states another species forkleaf toothwort (Cardamine dissecta or C. multifida) occurs in similar habitats and hybrids are susptected.. The leaves of forkleaf toothwort are more highly dissected than those of cut-leaved toothwort and are toothless. In the northern and central portions of its range, cut-leaved toothwort also hybridizes with large toothwort (Cardamine maxima) to produce the hybrid Cardamine x incisa. This is hybrid strongly resembles cut-leaved toothwort.
Cut-leaved toothwort, and in fact all toothwort species likely occur in greater than currently documented numbers due to their ephemeral nature. An example of this recently occurred on the White Mountain National Forest. A historic record for cut-leaved toothwort was known from the Town of Rumney with no other clues to its location. During botanical surveys of a popular climbing area on the WMNF a population of this species was located 100 feet from the parking lot along a very popular access trail. Ecological and botanical inventory work has been conducted at this site in the past, but this population was never observed because the surveys took place at the wrong time of year. This was only the third documented population of this species in New Hampshire and the first on the White Mountain National Forest.