5.
Iva annua
Linnaeus, Sp. Pl. 2: 988. 1753.
Iva annua
var.
caudata
(Small) R. C. Jackson;
I. annua
var.
macrocarpa
(S. F. Blake) R. C. Jackson
Annuals,
(10—)50—100(—150+) cm.
Stems
erect.
Leaves:
petioles 5—20(—30) mm; blades deltate or ovate to elliptic, trullate, or lanceolate, 30—100(—150+ × 8—45(—80) mm, margins ± toothed, faces ± scabrellous, gland-dotted.
Heads
in ± spiciform arrays.
Peduncles
0—1 mm.
Involucres
± hemispheric, 3—4(—5) mm.
Phyllaries:
outer 3—5 distinct, ± herbaceous.
Paleae
linear, 2—2.5 mm.
Pistillate florets
3—5; corollas 0.5—1 mm.
Functionally staminate florets
8—12+; corollas 2—2.5 mm.
Cypselae
2—3 mm.
2
n
= 34.
Flowering Jul—Nov. Disturbed sites, moist soils; 10—500 m; Ala., Ark., Colo., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Mass., Mich., Miss., Mo., Nebr., N.Mex., N.C., N.Dak., Ohio, Okla., Pa., S.C., S.Dak., Tenn., Tex., Va., W.Va., Wis.; Mexico (Tamaulipas).
