There are only about a dozen species in this group, distributed from California northwards into Washington. In gardens, much material is of hybrid origin, mainly derived from Iris innominata and I. douglasiana, and the pure species are seldom available. If you are familiar with these hybrids, remember that many wild plants are likely to be both less showy and less easy to grow than garden hybrids. We sometimes have wild-collected seeds available but we now have parent-stocks of almost all species and subspecies, raised from correctly named wild seeds, growing under protection as a source of hand-pollinated seed. The possibility of hybridization with our cultivated stocks is unlikely but not impossible. Most grow wild in light woodland or among sparse scrub, usually on steep slopes. In cultivation they need excellent drainage and a neutral to acid soil. The most lime-tolerant and also the most vigorous garden-plant in the UK is I. douglasiana. In northern Europe, a site in full sun might be preferable to half-shade for most species. Although their foliage is more or less evergreen and their rhizomes are quite thin, all are tolerant of dry conditions in summer. I. innominata and I. thompsonii are excellent rock-garden plants. A few, such as I. hartwegii subsp. columbiana, I. fernaldii and I. munzii, might be best grown in a bulb-frame or perhaps a bed along a South- facing wall in the UK.

Seed sown at any time between late summer and midwinter will usually germinate quite well in spring. Some can be a little irregular in appearing. Seedlings can be sensitive to an excess of moisture during hot summer weather and are best handled in spring or early autumn when roots are active.

Nomenclature : These irises exemplify better than any other genus how much speciation is proceeding actively in California. The variation, intergradation and hybridization of the recognized taxa are considerable. Dr. Lee Lenz's 1958 classification published in Aliso 4, No.1 is the basis for all subsequent nomenclature. It was adopted by Munz in ‘A California Flora’, by Brian Mathew in 'The Iris' and more or less by the Jepson manual. This classification is a brilliant and acceptable compromise but do not imagine the species are always clearly defined units in the wild. Forest clearance and road-building have opened new channels for the migration of many taxa, so that the situation regarding the delineation of some is possibly more confused now than it was almost half a century ago.

Further information : 'The Iris' by Brian Mathew (1981) is still the best source of information on all the species of Iris. There is a pleasant little booklet published by the British Iris Society in 1967 : ‘A Guide to the Pacific Coast Irises’ by Victor A. Cohen. There are plenty other books of varying quality on irises and, though the information might often tend to be derivative, the names of and cultural advice on the Pacific Coast species are usually fairly reliable.

Enter 'californicae' in the 'description' field of 'search' to access a complete list of all the Pacific Coast irises listed in alphabetical order