Vernonia baldwinii Torr. - Ironweed

Vernonia baldwinii plant

Family - Asteraceae

Stems - To +1.5m tall, herbaceous, from a taproot, typically single from the base, simple below, branched near apex, erect, stout, green but becoming purple in full sun, velutinous, (the hairs whitish to ferruginous or purplish and multicellular).

Vernonia baldwinii stem

Leaves - Alternate, short-petiolate to subsessile. Petioles to +/-7mm long, velutinous. Blades variable, from lanceolate to ovate or oblong, serrate, acute to acuminate, slightly scabrous above, velutinous below (and often bluish-green in color), with many small teardrop-shaped granules below, to 15cm long, 8-9cm broad. The serrations of the margins often with a minute whitish apex. Veins of the leaf blade are impressed adaxially and expressed abaxially.

Vernonia baldwinii leavesFresh leaves.

Vernonia baldwinii leafAbaxial leaf surface close-up.

Inflorescence - Dense cymose arrangement of flower heads. Peduncles velutinous, to 2cm long.

Involucre - 7-8mm long (tall), 5-6mm in diameter. Phyllaries imbricate, green with purple margins and midrib, acuminate, with arachnoid pubescence externally, glabrous internally, to 6mm long, 2-3mm broad. The tips of the phyllaries typically spreading but sometimes appressed. Margins often fimbriate-ciliolate.

Vernonia baldwinii involucreInvolucre.

Ray flowers - Absent.

Disk flowers - Corolla deep pink, 5-lobed, glabrous. Tube to 1.2cm long. Lobes to 3mm long, recurved, glabrous, linear. Stamens 5, adnate in upper 1/3 of corolla tube. Filaments white, glabrous. Anthers yellowish, connate around style, partially to fully exserted, to 3mm long. Style pinkish-white, well exserted beyond corolla and anthers, bifurcate, (the tips recurved). Achenes white in flower, to 2mm long, slightly compressed, tuberculate, pubescent, 4-sided, 8-ribbed. Pappus of multiple capillary bristles to 7mm long and short scales to .5mm long. Bristles brown, barbellate. Receptacle flat, naked.

Vernonia baldwinii flowers

Flowering - May - September.

Habitat - Fields, prairies, rocky woods, glades, meadows, waste ground, pastures, thickets, roadsides, railroads.

Origin - Native to U.S.

Other info. - This striking species is found throughout Missouri. The plant is common in the habitats listed above. This and other species of Vernonia can be fairly variable and sometimes difficult to ID. Many of the plants in this genus form hybrids and thus make ID even more of a challenge. V. baldwinii grows well from seed and should be used more in cultivation. Flying insects are very fond of the flowers.
Steyermark breaks this species down into different varieties and forms. I won't go into those here as many of these integrate and are probably not valid.

Photographs taken at the Current River Conservation Area, Reynolds County, MO., 7-15-01.


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