Fragrance in Wild Western Gardens: Irises

By: Ray Collett

Ray Collett is the founder and director emeritus of the Arboretum at the University of California, Santa Cruz, where he…

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A typical, purple-flowered Iris macrosiphon from northern Mendocino County. Author’s photographs

A typical, purple-flowered Iris macrosiphon from northern Mendocino County. Author’s photographs

Fragrance is an attribute that should be connected with the genus Iris. Unfortunately, many experts are likely to testify that divinely fragrant irises hail from Eurasia and the North American kinds lack any noticeable fragrance.

Slowly, accurate observations are being made. Slowly, good words about this world do spread. Yes, we can learn more about our Wild Western plants.

Most irises native to the Wild West really do smell, although their aroma is commonly quite musty or odd. Some forms of native ground irises are utterly delightful, smelling like the grandest freesias and violets. Spring comes, and the odor of Wild Western ground irises rises up warm, sunny mountainsides and slides down cool canyons. How do you get more? The odor is fleeting and beguiling to the nose, and one ground iris plant may possess it, yet its neighbor won’t.

In North America, neither nearness to the ground nor the will of systematic botanists is a sure indicator of the quality of iris fragrance; even geography is not a perfect guide. In California, the best smelling irises are to be discovered from around San Jose northward to Laytonville (in Mendocino County), or Garberville or Zenia (in southern Humboldt County). There is no substitute for sniffing them, which is not what most of us are inclined to do, since the best smelling irises flower almost flat on the ground. Some of these irises are assignable, more or less, to Iris macrosiphon, but, to complicate matters, some in that species completely lack any noticeable fragrance.

To confuse us further, even taller irises that do not quite fit the description of Iris macrosiphon sometimes smell heavenly. Perhaps some systematic botanists do not consider smell especially important, particularly in defining a species? It seems that many modern plant breeders make a mess of perfection, negligently short-changing irises with enhanced brilliance, size, and ruffles—but with little regard for fragrance. If any Wild Western iris cultivars smell as good as the wild ones, where are they?

What are we to do? By closing our pocketbooks, we can begin telling all manner of hybridizers and retailers just what is important, assuring them that fragrance is one of the great pleasures of an increasingly dismal world—a world given over to crassness and glitz.

A lavender variant from northern Mendocino County.

A lavender variant from northern Mendocino County.

Iris All Around Us

Excerpted and adapted from Native Treasures: Gardening with the Plants of California, by M Nevin Smith (UC Press, 2006).

Iris macrosiphon and Iris fernaldii are two very similar species with overlapping ranges in northern and central California, further blurred by their propensity to hybridize and intergrade. They form tight clumps with short, slender rhizomes. The leaves are narrow, usually of a dull surface, and blue green to gray green in color. The color of the leaf bases is supposed to be a distinguishing feature, being white in macrosiphon and reddish in fernaldii, but there are many exceptions.

The plants in both cases are most often eight to twelve inches tall; however, some charming miniature forms inhabit portions of the range (my favorites are those of northern Lake County). Both have long-tubed, broadly parted to rather spidery blossoms borne in pairs. Flower color in Iris fernaldii is typically creamy yellow, while I. macrosiphon varies from white to deep yellow and, more commonly, pale lavender to deep purple.

Plants of both species prefer a distinct summer drought but are otherwise rather easy to grow. They have played a minor role in the modern hybrids, extending their color range and reducing plant size. Their potential for imparting heat and drought tolerance seems to have received less attention. I have used selected forms of Iris macrosiphon with all of these  features in mind, and have had some pleasing results.