Description ³

Rhizomes freely branching, forming large colonies, slender, 0.8–0.9 cm diam., covered with remains of old leaves; roots fibrous. Stems 1–4-branched, solid, 1.5–7 dm. Leaves: basal with blade yellow-green, occasionally darker green, sometimes flushed pink or red basally, prominently ribbed, linear, 4.5–10 dm × 2 cm, apex acute; cauline 1–3, reduced. Inflorescence units (2–)3-flowered, branch units 2–3-flowered; spathes opposite or separated, divergent, green, sometimes flushed purple basally, lanceolate-acuminate, 6–12 cm × 7–12 mm. Flowers: perianth deep red-purple, lavender, gray-blue, cream, or white, with gold signal and blue or purple veins; floral tube 1.5–2.8 cm, usually widening to bowl shape at base of flower; sepals oblanceolate to obovate, 5–9 × 1.4–3 cm, base gradually attenuate, apex obtusely rounded; petals oblanceolate, 4.5–7 × 0.9–1.8 cm, base attenuate to narrow claw; ovary elliptic-oval, sharply triangular in cross section, 3–4 cm; style 1.7–3.5 cm; crests overlapping, subquadrate, 1–2 cm, margins coarsely toothed; stigmas triangular; pedicel 2–5 cm. Capsules sharply triangular in cross section with ridge at each angle, tapering at both ends, remnant of floral tube forming tip at apex, 2.5–5 cm. Seeds dark brown, pyriform, wrinkled. 2n = 40.

Establishment ⁴

The native irises are excellent in shade situations, even dense shade of walls and fences (Schmidt 1980). They will tolerate sun for most of the day in mild areas, and should have afternoon shade and ample water in the interior regions. Plants may be watered the year round. Fertilization increases biomass and seed production. This iris has a clumping rhizome system, and is readily propagated by plant division in fall or winter.

When allowed to increase freely, plants will naturalize and eventually form extensive ground cover. Unless the seed vessels are removed there will be many volunteer plants, but if inferior flower size or color appears it should be culled immediately. Irises start growing with the first cool weather and rains in fall, reaching the height of their growth in spring and early summer. They go dormant after seed set, in hot dry summer.

Propagation by Plant Division: Iris douglasiana is clonal, radiating outward in growth from the center. The best propagation method for these is division, in fall or winter after the first new roots are established but before the flowers form.

Native irises in the wild tend to produce only a small, dry rhizome with stringy roots, which is difficult to dig. Vigorous garden or greenhouse plants produce firm, white, growing roots especially in winter and spring growing seasons, and clumps are easily divided at those time. Remove a new fan with fleshy roots set in a prepared site, water it, and provide shade for a few days if the plant is placed in full sun. Frequent division appears to keep the plants vigorous, as well as being the best method of increasing the supply of superior forms.

Propagation by Seed: Iris seed is easily collected from the large capsules. The capsules turn from green to brown and open at the top when they are ripe. They have to be watched closely, because they disperse rapidly. Two days after ripening, the seed is gone. Collect capsules carefully to avoid spilling seeds. Each capsule has from 20 to 80 seeds.

Seeds should be stored in paper envelopes at room temperature until they are planted. The seeds of all species will keep up to 10 years at room temperature.

Plant seeds in 6-inch pots, using a combination of leaf mold and peat moss. Cover seeds with 1/2 inch of same material. Any good potting soil that's acidic is good for seed germination.

After planting, over-winter the pots outdoors in November or December. They will come up in 2-3 months, depending on the weather. Germination increases the second year, because there's always a percentage of hard seeds that won't germinate the first year. Part of the seed waits for the next year, to increase the probability for good weather conditions and optimize germination success.

Plant the seedlings in May, when the young plants are usually 3 to 6 inches tall or even taller. Plant from 6 inches to one-foot spacing. If a natural look is desired, scatter and clump the plantings. Water plants through the dry season until the roots have established. After the first year the plants should be self-maintaining without additional watering, unless there is an unusually hot, dry spell. Plants will begin to bloom by their second year if growth has been continuous.

Direct seeding is possible in places that can be left undisturbed, as among shrubs, or among low perennials where the seedlings can be sheltered. If planting seeds in the ground, autumn is the best time for seeding; germination begins in two or three months and often continues beyond that time. A friable seed mixture of sand, loam, and either peat or screened leaf mold is best, covering the seed with sphagnum moss to aid in preventing damping-off of seedlings.

Distribution ⁵

For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. Iris douglasiana grows abundantly along the coast from north Santa Barbara County, California, into Oregon. It is found in shade with moist soils with ample organic matter. This plant is common in grassy places, especially near the coast, at elevations generally less than 100 m. It grows naturally in the coastal prairie and mixed evergreen forest communities.

Fuentes y créditos

1. (c) Mike Baird, algunos derechos reservados (CC BY), http://www.flickr.com/photos/mikebaird/5539071094/
2. (c) Terrie Schweitzer, algunos derechos reservados (CC BY-NC-SA), http://www.flickr.com/photos/terriem/2441727353/
3. Adaptado por Gabby Padilla del trabajo de (c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, algunos derechos reservados (CC BY-NC-SA), http://eol.org/data_objects/5018552
4. (c) USDA NRCS National Plant Data Center, algunos derechos reservados (CC BY-SA), http://eol.org/data_objects/1385916
5. (c) USDA NRCS National Plant Data Center, algunos derechos reservados (CC BY-SA), http://eol.org/data_objects/1385915

Más información

• NaturaLista página del taxón
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• eFloras.org
• Flora of North America (beta)
• Global Biodiversity Information Facility (GBIF)
• HOSTS - a Database of the World's Lepidopteran Hostplants
• IPNI (with links to POWO, WFO, and BHL)
• Jepson eFlora
• NatureServe Explorer 2.0
• OregonFlora.org
• SEINet Symbiota portals
• Tropicos
• USDA PLANTS database
• World Flora Online

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