Small Head Marsh Elder

Annuals, 10–70(–100) cm. Stems erect. Leaves: petioles 0–1 mm; blades linear to filiform, 10–35(–60) × 0.6–1.5(–3) mm, margins entire, faces ± scabrellous, gland-dotted. Heads in ± spiciform arrays. Peduncles 0.5–1 mm. Involucres hemispheric, 1.5–2 mm. Phyllaries: outer 5 distinct, ± herbaceous. Paleae cuneiform to setiform, 1–2 mm. Pistillate florets 2–3+; corollas 0.5–0.8 mm. Functionally staminate florets 3–5; corollas 1.8–2 mm. Cypselae 1–1.5 mm. 2n = 32.

Iva microcephala Nutt. Trans. Am. Phil. Soc. II. 7: 346
1840.
A slender annual; stem 4-10 dm. high, terete, striate, sparingly strigose or glabrate, branched above; leaves alternate, linear, 2-5 cm. long, 1-3 mm. wide, sparingly strigose and glandular-punctate; those ot me inflorescence shorter and spreading; heads numerous, in slender, leafy spikes; involucre hemispheric, 3 mm. broad; bracts 4 or 5, distinct, obovate, glabrous, glandular-punctate, with narrow margins; paleae filiform with clavate tips, glandular-granuliferous; staminate and pistillate flowers usually 3 each, the corollas of the former funnelform; anthers with acuminate incurved tips; style half as long as the stamens; stigma minute; corollatube of the pistillate flowers truncate, shorter than the ovary; aehenes lenticular, obovate, pilosulous when young, in age murieulate, a little more than 1 mm. long.
Type locality: Florida.
Distribution: Pine barrens, from South Carolina to subtropical Florida.

Iva microcephala, the piedmont marsh elder, is a North American species of flowering plants in the family Asteraceae. It grows in the southeastern United States in Alabama, Florida, Georgia, and the Carolinas.

Iva microcephala is a wind-pollinated annual herb sometimes as much as 100 cm (40 inches) in height. Leaves are very narrow, sometimes thread-like, up to 6 cm (2.4 inches) long. Flower heads are small, clustered in elongated arrays at the tips of branches, each head containing only about 5-8 flowers.