Northern Prairie Wildlife Research Center
Western Wetland Flora
Field Office Guide to Plant Species
Iva axillaris Pursh
- Family: Composite (Compositae)
- Flowering: May-September
- Field Marks: The genus Iva consists of species with inconspicuous heads comprised only of greenish white, short, tubular flowers. The bracts are united at the base to form a cup.
- Habitat: Salt marshes, alkaline flats.
- Habit: Perennial herb with creeping rhizomes.
- Stems: Upright, or lying flat before becoming upright, branched or unbranched, up to 2 feet tall, smooth or hairy.
- Leaves: Lower leaves opposite, upper leaves alternate, all simple, obovate to oblanceolate, up to 2 inches long, up to 3/4 inch wide, rounded or somewhat pointed at the tip, tapering to the nearly sessile or sessile base, without teeth, 3-veined
- Flowers: Several crowded into nodding heads, with a single head in the axils of the leaves, each head up to 1/4 inch across, consisting only of greenish white tubular flowers: bracts subtending each head united to form a cup.
- Sepals: 0.
- Petals: 5, greenish white, united to form a short, tubular flower.
- Stamens: 5.
- Pistils: Ovary inferior.
- Fruits: Achenes obovoid, smooth although sometimes glandular, up to 1/8 inch long.
- Notes: The outer flowers of the disk are only female, while the inner flowers have both stamens and pistils.
Previous Species -- Bog St. John's-wort (Hypericum anagalloides)
Return to Species List -- Group 7
Next Species -- Marsh Felwort (Lomatogonium rotatum )