Iris hexagona Seeds | Dixie Iris
LATIN NAME: Iris hexagona
COMMON NAME: Dixie Iris, Six-angled Iris
Plant Profile
Dixie iris is a blue-violet wetland iris of the southeastern United States, with a seed pod that dries into six angled faces. It grows in freshwater marshes, wet pine savanna, ditches and the edges of swamps on the coastal plain from South Carolina to Florida and west to Louisiana, often standing in water for part of the year. The plant forms thick clumps of sword-shaped leaves a metre tall, with a stout green rhizome at the surface of the mud. The flowers appear in April and May, two or three to a stem, in shades of blue, violet and occasionally white, with a yellow signal on the falls. The capsule that follows is the reason for the name: it is six-ribbed and almost hexagonal in cross-section. The species is one of the group known to gardeners as the Louisiana irises, which hybridise freely and have produced a large race of garden cultivars.
Science & Biotechnology
Iris hexagona belongs to the Louisiana iris group, a cluster of closely related species that occupy different habitats across the southeastern coastal plain and exchange genes wherever those habitats meet. The group is a textbook case of hybrid speciation: where I. fulva, I. brevicaulis and I. hexagona come into contact, their hybrids are fertile and backcross repeatedly, producing swarms that are difficult to assign to a species. Each parent is adapted to a different water regime, from shallow flowing water to seasonally dry prairie, and the hybrids often occupy the intermediate ground. Dixie iris itself is the most salt-tolerant of the group and grows in brackish marshes near the coast, where few other irises survive. Its rhizome sits at the soil surface, anchored by fibrous roots, and the plant spreads by branching rather than by seed in established stands. Seeds need to stay wet and cool, and they germinate the following spring.
Uses & Benefits
The species is planted in bog gardens, pond margins and rain gardens, and it is one of the parents of the large-flowered Louisiana hybrids sold in garden centres. It is used in wetland restoration and in brackish sites where its salt tolerance gives it an advantage over other iris species. The rhizomes have been used in folk medicine as a poultice, and the roots yield a dark dye, though neither use is common now. The leaves are used for weaving in some coastal communities. In a garden the plant is valuable for its tolerance of standing water and its resistance to deer, and it will hold a bank against erosion. It needs to be divided every few years or the centre of the clump dies out and flowering declines. It is a poor choice for a small border, since it spreads steadily and its leaves flop over paths.
Growing from Seed
Sow seed fresh in autumn in a pot standing in water, and keep it outdoors through winter; germination is in spring and can be irregular. Alternatively divide rhizomes in late summer, cutting the leaves back to 15 cm and replanting the young outer sections with the rhizome just at the soil surface. Plant in full sun in wet, acid soil, or in a basket at the edge of a pond with the crown above water. Keep the site consistently moist through the first year, then allow natural water levels to take over. Feed once in spring with a low-nitrogen fertiliser, since too much nitrogen gives leaf and no flower. Lift and divide every third year in late summer, discarding the woody centre of the clump. In cold districts mulch the crowns with straw for the first winter, though established plants take hard frost.
Our Take
A tough southern wetland iris with hexagonal pods and a tolerance for brackish water. Give it wet feet and room to spread.
Related Reading
Gardeners who grow Dixie Iris often pair it with these related subjects: