Artemisia is more about form and foliage than flowers

It's not often that a scientific name is prettier than a common one, but in the cases of felon herb, wormwood and mugwort, 18th century botanists improved the ring when they renamed the plants after Artemis, the Greek goddess of the hunt. The change seems especially fitting after one encounters even a handful of the 500 or so species covered in the genus. The artemisia commonly found in Southern California are so understated yet so affecting that when we come near them, they stamp the senses. Whether a person recognizes it or not, artemisia will have owned that moment in the outdoors.

Different kinds are all around us, hiding in plain sight. In the kitchen, they are dinky little pots of tarragon. In the garden, they are billowing stands of wormwood. In the wild, there are great plains covered by sagebrush.

It takes a moment to accept the idea of them as a genus, to allow one's inner skeptic to mentally mutter, "If you say so ... " For the gardener, tarragon seems as unlikely a relation to sagebrush as dill might be to a pine tree. The fit for wormwood is no easier. The shape of its flat leaf brings parsley to mind. Scent might be even more misleading than shape. Their pungent aromatics are what led a number of them to be called "sagebrush" in the first place, when none of them are sages.

From the California gardener's perspective, one of the soundest rules of thumb for approaching the group is that the plants tend to be more about the form and foliage than the flowers. The western native, Artemisia tridentata, is the gnarliest of the clan. Even taken from the wild and grown in the most sheltered corner of a garden, it adopts a dramatic, windblown aspect. Watering the plant more than occasionally will kill it, so choose a dry spot, then use it next to a flowering plant as relief from the Laura Ashley effect of the blooms.

Whatever you mix with it, it will never compete with other flowers. Only the most alert gardeners even spot the columns of tiny, petal-less flowers forming on sagebrush in July. The plants do not produce showy petals because they are wind-pollinated, says Leila Shultz, a taxonomist at Utah State University and presiding American authority on artemisia. As the plant evolved, it did not waste energy producing extravagant floral appurtenances to attract bees that it didn't need for procreation. The plant's woodiness, Shultz says, signals that it evolved to withstand cold winters.

Follow artemisia into more temperate zones, and the woodiness diminishes, and it begins to flop. Artemisia californica can be as wispy as dill and run from silver to, in the case of the curiously named 'Canyon Gray' variety, a more marine green. It's worth looking for it sold by the plug and using it as ground cover.

Technically, the leaves of the gnarly and floppy sagebrushes are edible, but woe betide the consumer. The leaves are intensely bitter. Their charm is in their aroma. Possibly to deter predators, possibly as part of the plant's coolant system, sagebrush leaves are packed with chemicals called terpenoids and sesquiterpene lactones. The same class of chemicals puts the allure in mown grass, crushed pine needles, most sages and freshly squeezed lemon. But the cocktail in sagebrush is special. To hikers and cowboys, this is the scent of the West.

In contrast to its rugged American cousin, tarragon (Artemisia dracunculus) wouldn't survive a French second in the wild, or even too far out of sight in a sheltered garden. If snails don't get it, heat, drought or people will. It is bright green, tender, and if you ever do a Chinese garden around a doll's house, it could stand in as a miniaturized bamboo. Otherwise, the best place to grow it is on windowsills, where it can enjoy more water and less heat and the watchful eye of the cook who paid for it. Its leaves are delicious plucked straight from the plant, like a licorice drop, but even better on chicken with cream and brandy, or with red wine vinegar, olive oil, sea salt and roasted beets.

Wormwoods are commonly sold in the culinary herb section of good nurseries, though recipes containing them are scarce. They are where the kitchen garden meets the physic garden. Although the name is a common one and can mean any of dozens of artemisia, in California chances are good that they will be Artemisia absinthium or A. annua. Both plants have timeless standing as sources of drugs, medicinal and recreational. Egyptians have used A. absinthium as a vermifuge, or to worm sheep, going back to Pharaonic times. The Chinese have long sworn by A. annua to treat malaria (something that now even Western medicine acknowledges is effective). Once upon a time, the English used A. absinthium as a kind of Old World insect repellent (effectiveness unknown), more recently the French as an inebriant in absinthe (effective -- so effective, it is thought to have put the blur in Impressionism).

My own interest in wormwood began with the desire to make home-brew absinthe, but I became distracted by the glory of the plant in flower while gardening and never got around to building a still. It took growing Artemisia absinthium to realize that great flower gardens are made as much by background as the flowers themselves.

What came in little herb pots became billowing flotations -- 3 feet wide, 2 feet high -- of open-palmed, tender leaves, the ones that look like outsized gray-green versions of Italian parsley. They were so supple, they bounced back unfazed after intrusions from balls, children and dogs, then they even perfumed the intruders, leaving them too fragrant to scold. But the crowning grace was the color. The leaves of Artemisia absinthium seem to change with the light, running the gamut of blue-greens of the Pacific in the calm late summer days of the Santa Anas. It may be the prettiest shade of green in nature. The hybrid 'Powis Castle' has smaller leaves and is less green, more gray.

Where it occurs, the silvering of artemisia is caused by tiny hairs, which give the leaves a slightly velvety quality and reflect the sun. In the case of A. absinthium and 'Powis Castle,' this increases their water efficiency so dramatically that they can be planted with California natives. In this setting, they compensate for ratty foliage while complementing lush-lipped salvia blossoms, penstemons and fading heads of mauve bergamot. There's not a flower that doesn't look good set against it.

In a recent sweeping treatment of artemisia now in press with the Flora of North America Project, Shultz had to ask herself if she believed that sagebrush and tarragon and wormwood all belonged in the same genus. To her mind, the argument is still open, and thoroughly tantalizing, but for lack of a convincing alternative, she left the traditional grouping.

The challenge is to explain how they are related. The discovery of fossilized pollen places the oldest recognized artemisia in Asia about 33 million years ago, in the Oligocene Epoch. To explain how this led to formation of the sagebrush ocean of the Great Basin, evolutionary biologists are wondering if artemisia stock didn't arrive in a series of incursions, first from Siberia across the Bering Strait, through Alaska and Canada, another maybe later along another route, say the long way around the world through Europe.

The seeds might have blown here, or they might have been carried by animals. Where elk now browse on artemisia seed heads across sweeping reaches of the American West, dinosaurs might have foraged.

Kneeling in my flower garden, I'm glad I'd have an appropriate morsel on hand if a hungry behemoth wandered through. I'm also comforted knowing that one flowerbed over, I have the fixings for absinthe. But so far I don't seem to be able to break away to build the still. I'm busy admiring the butch elegance of A. tridentata next to the Jerusalem sage.

Emily Green can be reached at emily.green@latimes.com.

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