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Montana Field Guide

Montana Field Guides

Bractless blazingstar - Mentzelia nuda

Species of Concern

Global Rank: G5
State Rank: S1S2
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value:

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State Rank Reason (see State Rank above)
Rare and peripheral in Montana, where it is known from a few locations in the eastern half of the state. Additional data on population levels and trends are needed.
 
General Description
Bractless Mentzelia is an herbaceous biennial or short-lived perennial with one to a few erect, branched stems that arise from a taproot and are up to 1 m high. The lance-shaped, alternate leaves are 4-10 cm long, have deeply-toothed margins, and are petiolate below but sessile above. Foliage is covered with short, barbed hairs that cause it to stick to clothing like velcro. Flowers that open in late afternoon are borne on short stalks arising from the axils of reduced upper leaves, or bracts. Each flower is 4-9 cm across and has 10, non-overlapping, white petals and numerous exserted stamens. The calyx forms a deep bowl with 5 narrow, pointed lobes that are 10-25 mm long; it also contains the ovary and bears the stamens. The cylindrical seed capsules are 2-3 cm long.

Phenology
Flowering in July.

Diagnostic Characteristics
Mentzelia decapetala has ten white petals, its larger flowers are 8-15 cm across, and its petals overlap.

Species Range
Present
 


Range Comments
E. MT and SD south to CO, KS, and TX. Peripheral.

Summary of Observations Submitted for Montana
Number of Observations: 9

(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
Sandy or gravelly soil of open hills and roadsides on the plains.

References
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Citation for data on this website:
Bractless blazingstar — Mentzelia nuda.  Montana Field Guide.  .  Retrieved on , from