E-Flora BC: Electronic Atlas of the Flora of British Columbia

Amerorchis rotundifolia (Banks ex Pursh) Hultén
round-leaved orchis (roundleaf orchid)
Orchidaceae (Orchid family)

Introduction to Vascular Plants

© Bryan Kelly-McArthur  Email the photographer   (Photo ID #60917)

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Distribution of Amerorchis rotundifolia
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Introduction

Round-leaved orchis is one of North America's most beautiful wild orchid species. It is found in all Canadian provinces and territories (AB, BC, LB, MB, NB, NF, NT, NU, ON, QC, SK, YT) and in several northern US states (AK, ID, ME, MI, MN, MT, NH, NY, VT, WI, WY) (USDA 2010). It is also found in Greenland. Across its range, preferred habitat varies from limestone barrens and open tundra to coniferous forests, and bogs and moors. In British Columbia, this species is found throughout the province in sun or partial shade in moist forests, on streambanks, and in swamps and bogs in the montane zone. In Michigan, it is described as occurring on "alkaline to circumneutral mineral soil or marl under a Sphagnum moss-dominated groundcover" (Penskar and Higman. 1999). It is reported to favour sites "with a peristent, cold, groundwater source" (Penskar and Higman. 1999). In some areas, this orchid occurs with false solomon's seal (Maianthemum trifolium) and Labrador tea (Rhododendron groenlandicum).

Round-leaved orchis is a perennial rhizomatous species. Plant are distinctive, with a single ovate basal leaf, and up to 15 showy pink to white hooded, spurred flowers (about 1 cm in height) with (usually) purple or dark red spots. Plants may be up to 35 cm in height. Flowering period ranges from late June through July across its range, although it has been photographed in flower as early as June 9. The earliest specimen record of this species in the UBC Herbarium is from Ingenika River in 1914, collected by George V. Copley.

Species Information

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General:
Perennial herb from short rhizomes, with fleshy, fibrous roots; stems 10-20 cm tall, leafless, smooth.
Leaves:
Single, basal or nearly basal, round to elliptic, smooth, 3-7 cm long, 2-7 cm wide, unstalked or nearly so.
Flowers:
Inflorescence a few-flowered terminal raceme of showy flowers; sepals and lateral petals whitish to pink; sepals 3- to 5-veined, narrowly egg-shaped, 6-10 mm long; petals 2- to 3-veined, narrower than sepals, 5-6 mm long; lip 5-10 mm long, 3-lobed, the terminal lobe much larger, white with purple to dark red spots, the spur 3-7 mm long.
Fruits:
Capsules, ellipsoid, about 15 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist, mossy forests, streambanks, swamps and bogs in the montane zone; infrequent throughout BC east of the Coast-Cascade Mountains; N to AK, YT and NT, E to NF and S to ME, MI, WI, MN, WY and ID.

Source: The Illustrated Flora of British Columbia

Ecology

Ecological Framework for Amerorchis rotundifolia

The table below shows the species-specific information calculated from
original data (BEC database) provided by the BC Ministry of Forests and Range.
(Updated August, 2013)

Site Information
Value / Class

Minimum

Average

Maximum

Elevation (metres) 6 979 1520
Slope Gradient (%) 0 6 60
Aspect (degrees)
[0 - N; 90 - E; 180 - S; 270 - W]
0 293 354
Soil Moisture Regime (SMR)
[0 - very xeric; 4 - mesic;
8 - hydric]
2 5 8
Modal Nutrient Regime
Class
D
Number of field plots
 species was recorded in:
45
Modal BEC Zone Class
IDF
All BEC Zones (# of stations/zone) species was recorded in: BWBS(6), CWH(1), ICH(1), IDF(18), MS(4), SBPS(3), SBS(3), SWB(1)

Climate

The climate type for this species, as reported in the: "British Columbia plant species codes and selected attributes. Version 6 Database" (Meidinger et al. 2008), is montane boreal & cool temperate.

Synonyms and Alternate Names

Orchis rotundifolia Banks ex Pursh
Orchis rotundifolia var. lineata Mousley
Ponerorchis rotundifolia (Banks ex Pursh)

Taxonomic and Nomenclatural Links

Additional Photo Sources

Related Databases

General References