Iva xanthifolia, Nutt.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 142

1. I. xanthifolia Nutt. , Gen. N. Amer. Pl. 2 ’. 185 (1818).

Annual, with erect, branched stems up to 200 cm, glabrous or hairy. Leaves 7-30 cm, more or less opposite, petiolate, 3-veined, broadly obovate-subcordate to rhombic, sometimes 3- to 5-lobed, coarsely serrate, scabrid above, hairy beneath. Capitula numerous, greenish-white, sessile or on short peduncles, in axillary and terminal, leafless spikes or panicles. Involucre turbinate. Functionally male florets 8-20, with filiform scales; female florets usually 5, with obovate, ciliate scales. Corolla of functionally male florets c. 2-5 mm; of female c. 0-5 mm or obsolete. Achenes c. 3 mm, muricate, dark brown. 2« = 36. Cultivated ground, railway-lines and waste places. Naturalized in E. C. & S.E. Europe and in France-, casual elsewhere. [Au Cz Ga Ge Hu Po Rm Rs (C, W, E).] (North America.)