41. Iodanthus (Torrey & A. Gray) Steudel, Nomencl. Bot. ed. 2. 1: 812. 1840.
[Greek iodes, violet-colored, and anthos, flower] [Greek iodes, violet-colored, and anthos, flower]
Ihsan A. Al-Shehbaz
Cheiranthus Linnaeus [unranked] Iodanthus Torrey & A. Gray, Fl. N. Amer. 1: 72. 1838
Perennials; not scapose; glabrous or sparsely pubescent. Stems erect, branched distally. Leaves basal and cauline; petiolate or sessile; basal (withered by flowering), not rosulate, petiolate, blade margins lobed or not; cauline petiolate (petioles winged) or sessile, blade (base auriculate), margins dentate, entire, or lyrately lobed. Racemes (lax), considerably elongated in fruit. Fruiting pedicels divaricate to ascending, slender or stout. Flowers: sepals erect to ascending, oblong, lateral pair not or slightly saccate basally; petals purple, pink, or white, spatulate, (longer than sepals), claw differentiated from blade; stamens tetradynamous; filaments not dilated basally; anthers linear to narrowly oblong, (apiculate); nectar glands: lateral annular, median glands confluent with lateral. Fruits siliques, sessile or shortly stipitate, linear, smooth, terete; valves each with distinct midvein, glabrous; replum rounded; septum complete; ovules 22-36 per ovary; style distinct; stigma capitate. Seeds uniseriate, plump, not winged, oblong; seed coat (minutely reticulate), not mucilaginous when wetted; cotyledons accumbent.
Species 1: c, e United States.
R. C. Rollins (1993) recognized four species in Iodanthus, of which three are endemic to Mexico. As summarized by R. A. Price and I. A. Al-Shehbaz (2001), molecular data clearly support treatment of the genus as monospecific and closely allied to Cardamine, as well as recognition of the three Mexican species as members of Chaunanthus, a genus unrelated to Iodanthus and members of the Thelypodieae.
SELECTED REFERENCE Rollins, R. C. 1942. A systematic study of Iodanthus. Contr. Dudley Herb. 3: 209-215.