Douglas iris

I. douglasiana is a beardless iris typical of subgenus Limniris, series Californicae. It grows from a rhizome that is typically less than a centimeter in diameter. Its leaves are about 2 centimeters (0.79 in) wide and may grow up to 1 meter (3 ft) long. Leaf color ranges from yellow to dark green, with a more red appearance at the base. The flowers, appearing from April to June, are usually a purplish-blue, though occasionally white or yellow flowers are found. Two or three flowers are found on each stem, which is of variable height, ranging from 15–80 centimeters (5.9–31.5 in) tall. Flowers have three nectar-producing subunits, usually exhibiting both male and female parts (a stamen and style, respectively). I. douglasiana is protandrous, meaning pollen becomes available to pollinators before the stigma matures. However, male-sterile plants have also been found in the wild. These are less common, but may be less susceptible to damage from insect larvae. During pollination, bees typically visit only one subunit of the flower. This pattern, in addition to the protandrous flowering, reduces the likelihood of self-fertilization. Flowers mature into capsules containing up to 80 seeds.

I. douglasiana can be found in the wild in mainland coastal areas, ranging from southern Oregon to central California. It prefers sunny areas, usually found in grasslands and occasionally forests. It tolerates a range of soil types and can spread quickly after disturbances. It is usually found below 100 meters (330 ft) elevation.

I. douglasiana is frequently cultivated, both within its native range and beyond. Notably, this plant has gained the Royal Horticultural Society's Award of Garden Merit, indicating its suitability for gardening in the United Kingdom. New plants can be propagated from seeds or by separating growth connected by rhizomes. Left unattended, irises will spread in the immediate area through both of these methods. I. douglasiana can become infected by moth larvae of the species Macronoctua onusta (iris borer) and Amphipoea americana var. pacifica.