Mentzelia albescens (Gillies ex Arn.) Benth. & Hook. f. ex Griseb.
Wavyleaf Blazing Star
Family - Loasaceae
Stem - Erect, to 60 cm, brittle, whitish in color, densely pubescent with glochidiate, barbellate hairs.
Stem with complex hairs.
Leaf - Ovate-lanceolate, densely pubescent with barbed hairs, lobed or coaresly toothed.
Leaf margin with barbed hairs.
Inflorescence - Small terminal clusters or solitary.
Flowers - Actinomorphic, perfect, subtended by 1-3 narrow, entire bracts. Sepals 5. Hypanthium 10-20 mm long. Stamens 30-40 including 5 outer staminodes. Carpels 3, fused. Ovary inferior, with 1 locule. Flowers closed during the day, opening at dusk.
Corollas - Petals 5, bright yellow. Petalloid staminodes 5, indistinguishable from petals.
Fruits - Cylindrical capsules 18-28 mm long, densely pubescent externally with barbed hairs. Seeds numerous.
Flowering - May - August.
Habitat - Mine tailings, sandy disturbed areas.
Origin - Native to south-central U.S. and southward.
Other info. - This is one of the few Missouri representatives of a fascinating genus. The plants are covered with complex hairs which have been termed "pagodaform," with each hair bearing minute whorls of retrorse barbs. This feature causes plant parts such as leaves to stick tenaciously to fur or clothing, which can be a major nuisance in sheep ranching because this renders the wool unusable. Members of this genus are much more common in southwestern parts of the U.S., with M. albescens possibly arriving in Missouri as a railcar hitchhiker.
Photographs taken near Pacific, St. Louis County, MO, 8-11-2010 and 7-13-2012 (SRTurner).