- Scientific name: Corallorhiza odontorhiza (Willd.) Nutt.
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Special Concern (MA Endangered Species Act)
Description
Autumn coral-root, Corallorhiza odontorhiza, a member of the orchid family (Orchidaceae), is a pale to purple-brown plant without chlorophyll. Members of this genus in New England rely entirely on below ground fungal mycorrhizae for their nutrients. It is thought that the mycorrhizae are relying on dead organic matter present in the soil. It is frail and slender above, with a bulbous thickening at its base. Below ground is the branched, coral-like rhizome (underground, horizontal stem) that gives the genus its name. The 5-20 cm (2-8 in) high flower stalk is erect, leafless, and hairless. The raceme (elongate, unbranched inflorescence of stalked flowers) has from 5 to 15 small blossoms, each borne on a very slender, 2-3 mm (2/25-3/25 in) long, drooping stalk. The segments of the flowers spread very little but, rather, extend forward over the column (the structure formed in orchids by the fused male and female flower parts). Both sepals and petals are dark purple or purplish green. The white "lip," or lower-most petal, is 3-4 mm (3/35-4/25 in) long and is marked with a purple margin and two purple spots. The root system of C. odontorhiza gradually increases in size for several years before a flower stalk is produced.
Other species of coral-root do occur in our area and are somewhat similar in appearance. However, none blooms as late in the year as autumn coral-root. Spotted coral-root (C. maculata) blooms from early July to mid August and, rarely, to late August. In addition, it is taller than autumn coral-root, growing from 20-50 cm (8 to 20 in), compared to the 5-20 cm (2 to 8 in) of autumn coral-root. Early coral-root (C. trifida) blooms in spring and early summer, and its sepals and petals are greenish-yellow. The parasitic woodland plant beechdrops (Epifagus virginiana) blooms from August through October and could also be mistaken for autumn coral-root. However, the flowers of beechdrops, a member of the broomrape family (Orobanchaceae), are tubular in shape, and the plant has many branches.
Life cycle and behavior
Autumn coral-root blooms from early September to mid-October in Massachusetts.
Population status
Autumn coral-root is listed under the Massachusetts Endangered Species Act as a species of special concern. All listed species are protected from killing, collecting, possessing, or sale and from activities that would destroy habitat and thus directly or indirectly cause mortality or disrupt critical behaviors. There are 51 populations that have been verified since 1999 across Massachusetts in Berkshire, Franklin, Hampden, Hampshire, Norfolk, Middlesex and Worcester counties. There has been an increase of new populations observed recently.
Distribution and abundance
Autumn coral-root occurs throughout eastern North America, west into South Dakota and south through Texas, and into Central America. NatureServe ranks autumn coral-root as Secure (G5); however, despite the broad range, it is considered to be rare in many states and provinces. In New England, autumn coral-root is considered critically imperiled in Maine and Rhode Island, imperiled in Vermont, vulnerable in Massachusetts, apparently secure in Connecticut and not ranked in New Hampshire (NatureServe 2025).
Distribution in Massachusetts
1999-2024
Based on records in the Natural Heritage Database
Habitat
In general, autumn coral-root grows in either light soil or rich humus in open deciduous or mixed forests. In Massachusetts, it has been found in the wooded border of a brook; on a trail in open woodland; in a rich, limey forest; in a mesic woods at the base of a talus slope; in a forested, dolomitic limestone cobble; and in an open, medium dry woods. Among the species associated with C. odontorhiza are white pine (Pinus strobus), sugar maple (Acer saccharum), hemlock (Tsuga canadensis), spice-bush (Lindera benzoin), black birch (Betula lenta), sharp-leaved goldenrod (Solidago arguta), and common speedwell (Veronica officinalis). Autumn coral-root occurs at elevations ranging from sea level in North Carolina to 2.7 km (9,000 ft) in Mexico and Guatemala.
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
Threats to autumn coral-root include logging, road-widening, and general land development.
References
NatureServe. 2025. NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. Accessed: 5/23/2025.
Contact
| Date published: | April 10, 2025 |
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