Mentzelia oligosperma Nutt. ex Sims

Chicken Thief, Stickleaf

Mentzelia oligosperma plant

Family - Loasaceae

Stem - To 80 cm, branched and sprawling, brittle, densely pubescent with barbed hairs, whitish or gray.

Mentzelia_oligosperma_stemStem.

Leaf - Lanceolate to rhombic, coarsely and irregularly toothed or lobed, densely pubescent with barbed hairs.

Mentzelia_oligosperma_leafLeaf (abaxial).

Mentzelia_oligosperma_leaf2Pagodaform hairs at leaf base.

Inflorescence - Teminal clusters of a few flowers, or solitary.

Mentzelia_oligosperma_inflorescenceInflorescence.

Hypanthium - 4-6 mm long, densely pubescent with barbed hairs.

Mentzelia_oligosperma_hypanthiumHypanthium and stamens.

Flower - Sepals 5, deciduous. Petals 5, orange. Stamens 15-40. Staminodes absent.

Mentzelia_oligosperma_flowerCorolla.

Fruit - Capsule 7-14 mm long, cylindrical to clavate, densely pubescent with barbed hairs, with 1-3 seeds.

Mentzelia_oligosperma_fruitFruit.

Flowering - June - August.

Habitat - Ledges, bluff tops, glades.

Origin - Native to the U.S.

Other info. - This species is Missouri's only native Mentzelia. The common names refer to the tendency of the plant parts to adhere tenaciously to fur, feathers, or clothing. A field botanist whom I know has had Mentzelia leaves persist on his trousers through airline travel and subsequent laundering. This tenacity is caused by the presence of complex hairs bearing whorls of retrorse barbs. These "pagodaform" hairs are a distinguishing feature of the Mentzelia genus. Mentzelia oligosperma rewards early-rising observers with richly colored flowers, which are fully open only in the morning.
The species epithet "oligosperma" refers to the relatively small number of seeds per capsule.

Photographs taken at Castlewood State Park, St. Louis County, MO, 8-9-2010, and at Danville Conservation Area, Montgomery County, MO, 8-23-2016 (SRTurner).



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