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Green-band Mariposa Lily - Calochortus macrocarpus
Native Species
Global Rank:
G5
State Rank:
S3S4
(see State Rank Reason below)
C-value:
Agency Status
USFWS:
USFS:
BLM:
State Rank Reason (see State Rank above)
DRAFT: Requesting feedback on the 2026 revised rank, factors, and State Rank Reason outlined below and in the Conservation Status Rank Report.
Calochortus macrocarpus occurs in low-elevation habitats in northwest Montana, where it has been documented at roughly two dozen sites. These habitats are often affected by development, invasive species, livestock grazing, and other land-use practices. Current population levels are unknown, as are trend, though it is likely that the species has experienced long-term declines, particularly from habitat loss. As targeted surveys for the species have not been conducted, the species may be somewhat more abundant than the relatively few collections and observations would indicate, leading to uncertainty in its conservation status.
Surveys are needed at known sites to document population size and condition. Additional surveys in areas of potentially suitable habitat are also necessary to identify any new populations.
General Description
PLANTS: Herbaceous perennial plants that grow from bulbs. Stems are usually single and 20-50 cm tall. Source: Lesica et al. 2012.
LEAVES: Few, basal and alternately arranged on stem. Basal leaves are narrow (1-2 mm), channeled or inrolled, and usually shorter than stem leaves. Sources: Lesica et al. 2012; Giblin et al. [eds.] 2018.
INFLORESCENCE: Terminal, of 1 to 4 stemmed (pedicellate), purplish flowers. Bracts are 3-10 cm long. 3 sepals alternate with 3 petals. Sepals are narrow, often longer than petals, purplish, and 3-6 cm long. Petals purple, acuminate, and 3-5 cm long; outer surface with a green midvein; inner surface with an ovate, yellow-fringed gland and a crescent-shaped purple mark above. Sources: Lesica et al. 2012; Giblin et al. [eds.] 2018.
Montana's plants are of variety macrocarpus (Fiedler and Zebell in Flora of North America [FNA] 2002).
The genus, Calochortus, comes from the Greek words kalos meaning 'beautiful' and chortos meaning 'grass' (Fiedler and Zebell in FNA 2002).
Phenology
Flowering late spring to mid-summer (Fiedler and Zebell in FNA 2002).
Diagnostic Characteristics
Green-band Mariposa Lily -
Calochortus macrocarpus*Basal Leaf: Channeled, similar in width, but shorter than stem leaves.
*Anthers: Lanceoloid (round in cross-section; wider from base to below middle then tapering to the tip).
*Sepals: Usually longer than petals.
*Petals: Purple. Green striped on the outside. Tip acuminate.
Nuttall's Mariposa Lily -
Calochortus nuttallii*Basal Leaf: Channeled, similar in width, but shorter than stem leaves.
*Anthers: Oblong.
*Sepals: As long or shorter than petals.
*Petals: White to purple tinged, yellow at the base. Lacking a green stripe on the outside. Bearded on the inside, adjacent to gland. Tip apiculate.
Bruneau Mariposa Lily -
Calochortus bruneaunis, SOC
*Basal Leaf: Channeled, similar in width, but shorter than stem leaves.
*Anthers: Oblong.
*Sepals: Usually shorter than petals.
*Petals: White. Green striped on the outside. Nearly hairless on the inside (glabrate) near gland. Tip apiculate.
Gunnison's Mariposa Lily -
Calochortus gunnisonii*Basal Leaf: Channeled, similar in width, but shorter than stem leaves.
*Anthers: Apiculate (short, sharp tip).
*Sepals: Usually shorter than petals.
*Petals: White or yellowish to purple; greenish inside and sometimes purple-banded or -spotted next to gland. Green stripe absent on the outside. Tip not acuminate.
The following Mariposa Lilies differ from those above in that their basal leaves are flat, much wider than the stem leaves, and often more than half as long as the stem leaves:
Baker Mariposa Lily -
Calochortus apiculatus Elegant Mariposa Lily -
Calochortus elegans Big-pod Mariposa Lily -
Calochortus eurycarpus
Species Range
Montana Range
Range Descriptions
Native
Range Comments
British Columbia, Montana south to California and Nevada (Lesica et al. 2012).
Observations in Montana Natural Heritage Program Database
Number of Observations: 32
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Grasslands and pine woodlands in the valley zone of Montana (Lesica et al. 2012).
Ecology
For Calochortus, petal size can vary between years and may be associated with soil moisture (Lesica et al. 2012).
Reproductive Characteristics
Plants reproduce from seed.
PROPAGATION
Most species propagate easily from seeds (Giblin et al. [eds.] 2018). It takes from 3-5 years to grow from seed to a flowering bulb (Giblin et al. [eds.] 2018). Bulbs collected in the wild rarely survive when planted (Giblin et al. [eds.] 2018).
FLOWERS
Petals: 3, distinct, and purplish with an acuminate tip. At the base of the petal is a gland.
Gland: oblong-oval, more or less sagittate at the base, bordered with a mostly continuous fringed membrane, and has a surface covered with elongate, branched, thick hairs.
Stamens: 6, anthers are lanceoloid and longer than the filaments.
Pistil: Single with a 3-lobed style.
FRUITS
Fruit is a capsule. Capsule is spindle-shaped, erect, 4-5 cm long, and filled with many seeds. Ovary and capsules elongate greatly with age (longer than thick) and are not winged (Giblin et al. [eds.] 2018).
Stewardship Responsibility
Threats or Limiting Factors
In Montana plants are threatened by changes to the habitat from invasion of exotic plants.
References
- Literature Cited AboveLegend:
View Online Publication- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?- Cope, M.G. 1992. Distribution, habitat selection and survival of transplanted Columbian Sharp-tailed Grouse (Tympanuchus phasianellus columbianus) in the Tobacco Valley, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 60 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
Quire, R.L. 2013. The sagebrush steppe of Montana and southeastern Idaho shows evidence of high native plant diversity, stability, and resistance to the detrimental effects of nonnative plant species. M.Sc. Thesis. Bozeman, MT: Montana State University. 124 p.
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