Blue flag iris

A short-lived native perennial of wet woodland edges, stream banks, and ditches across the Americas, named for the brilliant scarlet-red flowers that rise on erect, unbranched terminal spikes from mid-to-late summer. Each tubular, two-lipped bloom is shaped for the hummingbird tongue - the plant depends on ruby-throated hummingbirds for pollination because most insects cannot work the long flower tube. It demands constant moisture and tolerates brief flooding, but its foliage carries alkaloids that are very toxic to humans if eaten.

Virginia iris (Iris virginica) is a marsh plant, and the commonest way to fail with it is to buy it as a border perennial. Missouri Botanical Garden puts it in wet, boggy, acidic, sandy soil in full sun, rates its water need medium to wet, and lists water plant, rain garden and naturalise as its uses; the Lady Bird Johnson Wildflower Center rates water use High, soil moisture Wet, and CaCO3 tolerance LOW. Read together that is a plant which wants saturated ground or shallow standing water and dislikes lime, which is close to the inverse of an ordinary well-drained bed on builders' subsoil. Planted in one it does not die dramatically; it thins, stops flowering and fades out over three or four seasons, and the gardener concludes irises are difficult. Sited properly it is among the best things a pond margin can hold: 1 to 3 feet of bright medium-green sword foliage that often lies out over the water, and violet-blue flowers in late spring carrying a bright yellow, conspicuously HAIRY signal patch on each fall. That signal is also the field mark - Iris versicolor, its near-identical northern counterpart already in this catalog, carries a flatter greenish-yellow signal with few hairs and heavier purple veining. The reason to know this species specifically is the sibling it replaces. Iris pseudacorus, the yellow flag in this same wave and the same botanical series, is a European wetland iris that has escaped into North American marshes and is regulated as a noxious weed in several states. If you want an iris standing in water at a pond edge, this and Iris versicolor are the two answers that do not get out. Two cautions carry across the whole genus: the rhizomes contain irisin and iridin and cause vomiting and diarrhoea if eaten and dermatitis on handling, and iris borer (Macronoctua onusta) is the pest that decides whether a rhizomatous iris planting survives in eastern North America.

A tall native eastern US perennial with deep purple-magenta flower clusters in late summer - among the most striking color in the native fall meadow palette. Tall and tolerant of wet feet; pairs visually with joe-pye weed + goldenrod for an iconic eastern wet-meadow trio.

A tall native northern + central North American perennial with whorled foliage on purple-spotted stems and broad rounded clusters of mauve-pink flowers in late summer. More cold-tolerant + moisture-loving than sweet Joe-Pye weed (E. purpureum); ideal for cold-climate rain garden + wet-meadow plantings.

A tall native perennial wildflower of moist meadows and woodland edges across eastern North America, producing large domed clusters of vanilla-scented pink-purple flowers in late summer - among the most reliable late-season nectar sources for monarchs, swallowtails, skippers, and native bees. Formerly classified as Eupatorium purpureum.

A long-lived native perennial of central and eastern US woodland borders and prairie meadows with deep blue pea-shaped flowers in late spring, blue-green leguminous foliage, attractive black seed pods for winter interest, and a nitrogen-fixing root system (Fabaceae). Larval host for 6 documented butterfly species per NC State (orange sulphur, clouded sulphur, frosted elfin, eastern tailed-blue, hoary edge, wild indigo duskywing) - among the highest Lep-host-count perennials in the eastern flora.