Montana Field Guide

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- Kingdom - Plants - Plantae
  - Division - Angiosperms (Flowering Plants) - Anthophyta
    - Class - Monocots - Monocotyledoneae
      - Order - Orchids - Orchidales
        
        Family - Orchids - Orchidaceae
        
        Species - Sparrow's-egg Lady's-slipper - Cypripedium passerinum

Sparrow's-egg Lady's-slipper - Cypripedium passerinum

Species of Concern

Global Rank: G4G5
State Rank: S2 * (see reason below)

Agency Status
USFWS: none
USFS: SENSITIVE
BLM: none
MNPS Threat Rank: 2

State Rank Reason

Sparrow's-egg lady's-slipper is known from over a dozen moderate to large-sized populations, a few dozen small occurrences and one historical location. Several of the occurrences are either in designated wilderness areas or in Glacier National Park. The main threat to populations appears to be from potential hydrologic changes resulting from timber harvest or other activities. Invasive weeds such as Canada thistle and ox-eye daisey pose a limited threat.

General Description

Sparrow's-egg Lady's-slipper is a perennial with leafy stems reaching up to 35 cm high and arising from slender, creeping rhizomes. The 3-5 broadly lance-shaped leaves reach up to 15 cm long and clasp the stem; the herbage is covered with long, soft hairs and is usually somewhat sticky. The one or two flowers are subtended by a leafy bract which is longer than the inflorescence. The sepals are green and 10-16 mm long, and the upper is longer than the lower two. The petals are white; the lower is pouch-like with purple spots on the inside, and the other two resemble the sepals but are shorter. The erect capsule is ovoid and bears thousands of tiny seeds.

Phenology

Flowering in late June-early August.

Diagnostic Characteristics

This species can be distinguished from our other white lady's slipper (C. MONTANUM) by the sepals that are shorter than the slipper-like petal and not wavy or twisted.

General Distribution

Mapped Occurrences

Summary of Observations Submitted for Montana

Number of Occurrences: 48

(Click on the following maps and charts to see full sized version) Map Help and Descriptions

Relative Density

Recency

(Records associated with a range of dates are excluded from time charts)

Distribution Comments
AK and Yukon to Hudson Bay and Quebec, south to se. B.C., n. MT, and to the region of Lake Superior. Peripheral.

Habitat

Mossy, moist, or seepy places in coniferous forests, often on calcareous substrates.

Citations & Sources

Arditti, J., J. D. Michaud and P. L. Healey. 1979. Morphometry of orchid seeds. I. PAPHIOPEDILUM and native California and related species of CYPRIPEDIUM. American Journal of Botany. 66(10):1128-1137.
Catling, P. M. 1983. Autogamy in eastern Canadian Orchidaceae: a review of current knowledge and some new observations. Naturaliste Canada 110:37-53.
Hoitsma, T. 1992. Sensitive plant survey, Fortine Ranger District, Kootenai National Forest. Unpublished report. 65 pp. plus appendices.
Horn, G. 1980. Report on inventory of threatened or endangered, rare, or sensitive plants-Headwaters Resource Area, Butte District, Bureau of Land Management, Montana. Unpublished report. 54 pp.
Keddy, C. J., Keddy, P. A. and R. J. Planck. 1983. An ecological study of CYPRIPEDIUM PASSERINUM Rich. (sparrow's egg lady-slipper, Orchidaceae) on the north shore of Lake Superior. Canadian Field-Naturalist 97(3):268-274.
Linden, B. 1980. Aseptic germination of seeds of northern terrestrial orchids. Ann. Bot. Fennici 17:174-182.
Shelly, J. S. 1988. Status review of CYPRIPEDIUM PASSERINUM, U.S. Forest Service, Region 1, Flathead and Lewis and Clark National Forests. Unpublished report. Montana Natural Heritage Program, Helena, MT. 52 pp.
St-Arnaud, M. and D. Barabe. 1989. Comparative analysis of the flower vascularization of some CYPRIPEDIUM species (Orchidaceae). Lindleyana 4(3):146-153.
Vanderhorst, J. 1996. Status report on sensitive lady's slipper orchids (CYPRIPEDIUM CALCEOLUS var. PARVIFLORUM and CYPRIPEDIUM PASSERINUM) on the Kootenai National Forest. Unpublished report to the Kootenai National Forest. Montana Natural Heritage Program, Helena, MT. 27 pp. plus appendices.

Citation for data on this website:
Sparrow's-egg Lady's-slipper — Cypripedium passerinum. Montana Field Guide. Retrieved on February 9, 2010, from http://FieldGuide.mt.gov/detail_PMORC0Q0A0.aspx