Arnoglossum plantagineum Raf.
Family - Asteraceae
Stems - To +/-80cm tall, glabrous, purplish below, with purple vertical striations, herbaceous, from short caudex with thickened roots, simple, erect.
Leaves - Alternate, glabrous. Basal leaves petiolate. Petioles to 10cm long, slightly winged. Blade tapering at base and winging petiole, ovate, typically entire or shallow toothed, to 15cm long, 7-8cm broad, thickened to semisucculent or leathery in texture, with main veins parallel. Cauline leaves strongly reduced, shallow toothed to entire, ovate to ovate-lanceolate.
Inflorescence - Corymbose cyme with many flower heads. Main branches of inflorescence and peduncles whitish, glabrous. Leaves reduced to bracts in inflorescence.
Involucre - To 1cm tall(long), 6mm in diameter. Phyllaries keeled and united, whitish, glabrous. Flower head with typically 5 flowers.
Ray flowers - Absent.
Disk flowers - Corolla 5-lobed, whitish. Corolla tube 8-9mm long, glabrous. Lobes to 3mm long, often recurved or curling. Stamens 5, exserted. Anthers orange to brown, 2.7mm long, connate around style. Style glabrous, bifurcate. Achenes green(in flower), terete, 2mm long in flower, 5mm long in fruit, with 10 ridges(nerves). Pappus of many capillary bristles to 8mm long.
Close-up of disk flowers.
Individual disk flower with pappus.
Flowering - May - August.
Fruits - Brown, 10-ribbed, beakless, with spreading pappus.
Habitat - Prairies, wet meadows, glades, rocky open woods, thickets, roadsides, railroads.
Origin - Native to U.S.
Other info. - It's hard to
miss this plant as you peer out across a mature prairie. The white flowers
and white branches of the inflorescence are sure to catch your eye. The
plant is very easy to identify in the field. If you wish to replant a real
prairie habitat, you must include this plant.
Photographs taken off Hwy NN, Shannon County, MO., 6-17-03, and off Hwy H, Shannon County, MO., 6-13-05 (DETenaglia); also at Onondaga Cave State Park, 6-18-2014 and 7-31-2014 (SRTurner).