Jepson eFlora: Taxon page
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Mentzelia hirsutissima

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

Mentzelia hirsutissima S. Watson
Habit: Annual 5--31 cm. Stem: erect, hairy, branched at base. Leaf: 1--11 cm, lanceolate to oblanceolate, toothed to lobed, upper sessile with lower lobes generally clasping. Inflorescence: bracts ovate to triangular, 4--10-toothed, +- clasping, green, base occasionally +- white. Flower: sepals 9--18 mm; petals 12--31 mm, obovate, pale yellow to orange, tip mucronate; stamens 4--12 mm, filaments +- broadened, generally distally 2-lobed, anther stalk between lobes thin, generally >= lobes; style 6--13 mm. Fruit: erect, 13--25 mm, 5--8 mm wide, cylindric. Seed: +- 2.5 mm, +- 1.5 mm wide, +- compressed, widest at middle, beaked, ashy-white.
Ecology: Washes, fans, slopes, creosote-bush scrub; Elevation: < 720 m. Bioregional Distribution: w DSon; Distribution Outside California: Baja California. Flowering Time: Apr--May
Synonyms: Mentzelia hirsutissima var. stenophylla (Urb. & Gilg) I.M. Johnst.
eFlora Treatment Author: Joshua M. Brokaw, John J. Schenk & Barry Prigge
Jepson Online Interchange
Listed on CNPS Rare Plant Inventory

Previous taxon: Mentzelia gracilenta
Next taxon: Mentzelia involucrata

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Citation for this treatment: Joshua M. Brokaw, John J. Schenk & Barry Prigge 2016. Mentzelia hirsutissima, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on October 21, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on October 21, 2016.

Geographic subdivisions for Mentzelia hirsutissima:
w DSon;
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.