Jepson eFlora: Taxon page
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Mentzelia micrantha

Higher Taxonomy
Family: LoasaceaeView DescriptionDichotomous Key

Habit: Annual to subshrub; hairs needle-like, barbed, occasionally stinging. Leaf: alternate [opposite], generally +- pinnate-lobed; stipules 0. Inflorescence: cyme, raceme. Flower: bisexual, radial; sepals generally 5, generally persistent; petals generally 5, free or fused to each other or filament tube; stamens 5--many, filaments thread-like to flat, occasionally fused at base or in clusters; petal-like staminodes occasionally present; pistil 1, ovary inferior, chamber generally 1, placentas generally 3, parietal, style 1. Fruit: capsule or achene. Seed: 1--many.
Genera In Family: 18+ genera, 250 species: especially America (Africa, Pacific).
eFlora Treatment Author: Larry Hufford & Barry Prigge, except as noted
Scientific Editor: Douglas H. Goldman, Bruce G. Baldwin.
Genus: MentzeliaView DescriptionDichotomous Key

Habit: Annual to perennial herb; hairs barbed to needle-like, not stinging; stems pale pink or generally +- white, branched or not. Leaf: linear to ovate, entire to pinnate-lobed; basal in rosettes, generally petioled; cauline generally sessile, +- reduced distally on stem. Inflorescence: generally cyme (or flower 1); bracts green to white, margin green. Flower: sepals lanceolate to deltate, persistent; petals generally 5, free, white to yellow or orange; stamens generally many, +- free, generally unequal, inner filaments generally thread-like; outermost stamens opposite sepal lobes generally modified, +- widened, or petal-like with anther or not; ovary generally cylindric, placentas generally 3, style thread-like, stigma 3-furrowed or -lobed. Fruit: capsule, cup-, barrel-, or urn-shaped to narrowly cylindric, occasionally curved. Seed: generally many, shape variable.
Species In Genus: +- 100 species: western North America, +- tropical America.
eFlora Treatment Author: Joshua M. Brokaw, John J. Schenk & Barry Prigge
Reference: Darlington 1934 Ann Missouri Bot Gard 21:103--226

Mentzelia micrantha (Hook. & Arn.) Torr. & A. Gray
Habit: Annual 10--80 cm. Stem: erect, hairy. Leaf: 1--18 cm, irregularly dentate, wavy or lobed. Inflorescence: bracts ovate to round, entire to crenate, generally concealing flower, green. Flower: sepals 1.5--2 mm; petals 2.5--4.5 mm, ovate, yellow; stamens 1.5--4 mm, filaments of 5 outermost widened, distally 2-lobed; style 2--3(5) mm. Fruit: erect to curved < 20°, 6--13 mm, 1.5--2.5 mm wide, cylindric. Seed: 5--10, 1.5--2.5 mm, +- 1 mm wide, +- prism-shaped, ×-section triangular, longitudinal edges grooved, tan and dark-mottled to black; seed coat cells minute. Chromosomes: 2n=18.
Ecology: Open, generally recent-burned or disturbed chaparral and oak woodland; Elevation: < 2256 m. Bioregional Distribution: KR, NCoR, CW, SW; Distribution Outside California: Baja California. Flowering Time: Apr--Jun
eFlora Treatment Author: Joshua M. Brokaw, John J. Schenk & Barry Prigge
Reference: Darlington 1934 Ann Missouri Bot Gard 21:103--226
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botanical illustration including Mentzelia micrantha


Citation for this treatment: Joshua M. Brokaw, John J. Schenk & Barry Prigge 2012, Mentzelia micrantha, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on January 19, 2018.

Citation for the whole project: Jepson Flora Project (eds.) 2018, Jepson eFlora,, accessed on January 19, 2018.

Mentzelia micrantha
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© 2017 Neal Kramer
Mentzelia micrantha
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© 2010 Gary A. Monroe
Mentzelia micrantha
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© 2014 Vernon Smith
Mentzelia micrantha
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© 2014 Aaron Schusteff
Mentzelia micrantha
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© 2011 Neal Kramer
Mentzelia micrantha
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© 2014 Aaron Schusteff

More photos of Mentzelia micrantha in CalPhotos

Geographic subdivisions for Mentzelia micrantha:
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.