Dwarf mentzelia - Mentzelia pumila
State Rank Reason (see State Rank above)
Rare in Montana, where it is known only from sandy sites within the Bighorn Basin area. Additional data on population levels and trends are needed.
Dwarf Mentzelia is an herbaceous biennial or short-lived perennial herb with branched, white stems that arise from a stout taproot and that are 2-6 dm tall. The lance-shaped basal leaves are 8-10 cm long and have short petioles and broadly-toothed margins. The alternate leaves become sessile, smaller, and more deeply lobed higher on the stem. The foliage is covered with short, barbed hairs that cause it to stick to clothing like velcro. 1-3 flowers are borne on short stalks arising from the axils of the reduced upper leaves, or bracts. Flowers have 10 yellow petals that are 9-15 mm long and numerous stamens, the outer of which are petal-like. The calyx forms a deep bowl with 5 narrow, pointed lobes that are 4-10 mm long; it also contains the ovary and bears the stamens. The cylindrical seed capsules are 15-20 mm long.
Flowering in June-early July.
This is our only Mentzelia with 10 yellow petals and our only perennial member of the genus with calyx lobes less than 10 mm long.
ND and south-central MT to CO, UT, and NV. Peripheral.
Observations in Montana Natural Heritage Program Database
Number of Observations:
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(Observations spanning multiple months or years are excluded from time charts)
Open, usually sandy soil in desert shrubland and woodland in the valley and foothill zones.
- Additional ReferencesLegend: View Online Publication
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- Brown, D. K. and R. B. Kaul. 1981. Floral structure and mechanism in Loasacae. American Jounal of Botany 68(3):361-372.
- Lesica, P. and P.L. Achuff. 1992. Distribution of vascular plant species of special concern and limited distribution in the Pryor Mountain desert, Carbon County, Montana. Unpublished report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 105 pp.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- North Dakota Natural Heritage Program. 1993. 1991-1992 inventory of rare plant species in the Little Missouri National Grasslands. Unpublished report to the Custer National Forest. Bismarck, North Dakota. 72 pp.