Iodanthus pinnatifidus (Michx.) Steud.
Family: Brassicaceae
Purple-Rocket,  more...
[Arabis hesperidoides (Torr. & A. Gray) A. Gray,  more]
Iodanthus pinnatifidus image
Paul Rothrock  
Stems 3-8(-10) dm, striate. Cauline leaves: (proximal) petiole (0.5-)1-4 cm, (narrowly to broadly winged), distal sessile; blade lanceolate, ovate, elliptic, or oblong, (3-)4-12(-15) cm × (12-)20-55(-70) mm, base cuneate to attenuate, or (distalmost) minutely to coarsely auriculate, margins usually minutely to coarsely, regularly or irregularly, dentate or serrate, rarely subentire, apex acute to acuminate, surfaces glabrous or pubescent. Fruiting pedicels straight or slightly curved upward, (2-)3-8 (-9) mm (nearly as thick as fruit). Flowers: sepals 3-6 × 1-1.5 mm, glabrous or subapically pilose; petals 7-12 (-14) × 1.5-2.5(-3) mm, attenuate to claw (claw 4-7 mm); filaments 3-6 mm; anthers 2-2.5 mm; gynophore obsolete or to 1 mm. Fruits usually divaricate to ascending, rarely erect, (1.5-)2-3.5(-4) cm × 1-1.5 mm; style (1-)2-4 mm. Seeds 1.2-1.5 × 0.7-1 mm. Flowering late Apr-early Jul. Shaded banks, thickets, wooded ravines, limestone or sandstone bluffs, bottomland woods, swamps, flood plains, creeks, streamsides; 50-300 m; Ala., Ark., Ill., Ind., Iowa, Kans., Ky., Md., Minn., Mo., Ohio, Okla., Pa., Tenn., Tex., W.Va.
Perennial herb with a large taproot to 1 m tall Stem: upright, unbranched or branched near the apex, keeled with longitudinal ridges, mostly hairless. Leaves: alternate, often pinnately divided towards the base, mostly stalkless (especially lower leaves, which have lobed bases and are partially clasping), to 15 cm long, to 4 cm wide, spatula-shaped below, lance-shaped above, bases tapering (resembling a stalk-like base), tips pointed to slightly pointed, toothed, thin. Flowers: in a long, branched cluster (raceme), which is borne terminally and laterally on the stem. Racemes 6 - 10 mm long. Sepals four, upright, light purple, green at apex, 3 - 6 mm long, to 2 mm wide at base, cupped, tips rounded. Petals four, spreading or reflexed, light purple to nearly white, 1 - 1.3 cm long, bases narrowed. Stamens six. Anthers purple. Fruit: a long, narrow pod (silique), widely spreading, 2 - 4 cm long, with a short beak. Seeds in one row.

Similar species: No information at this time.

Flowering: late May to early July

Habitat and ecology: Rare in the Chicago Region. Mainly found in wooded floodplains and other wet areas.

Occurence in the Chicago region: native

Etymology: Iodanthus comes from the Greek words iodes, meaning violet, and anthos, meaning flower. Pinnatifidus means "pinnately divided" and "finely cut."

Author: The Morton Arboretum

Perennial to 1 m, simple below the infl, glabrous or nearly so; lvs thin, lanceolate to elliptic or oblong, acute or acuminate, commonly sharply dentate, often laciniate, rarely double-dentate or merely crenate, tapering to a petiole-like base, frequently auriculate around the stem, the larger or lower often pinnatifid at base with 1-4 pairs of small segments; racemes elongating before anthesis; sep obtuse, 3-5 mm; pet 10-13 mm; pedicels 6-10 mm; frs slender, widely divergent, 2-4 cm, the valves covered with minute transparent papillae. Moist or wet alluvial woods; w. Pa. and W.Va. to Ill., Minn., Tenn., Kans., Ark., and Okla. May, June.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
From Flora of Indiana (1940) by Charles C. Deam
More or less frequent and locally common in moist, alluvial soil along streams and on the adjacent wooded slopes, rare elsewhere throughout the state although there are no specimens or records from the northern fourth of the state.
Iodanthus pinnatifidus image
Paul Rothrock  
Iodanthus pinnatifidus image
Paul Rothrock  
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Morton Arboretum  
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