Q: I have a few hybrid phormium in my yard, planted a year ago. Imagine my surprise to discover this summer that several of these plants began to revert to solid-color, larger-leaved plants.

Is there any way to stop this reversion from happening again? Is there anything I can do to prevent it from happening to other phormium plants in my yard? Are there particular hybrid varieties that don't revert, or is this something I need to monitor with all hybrid phormium?

A: All variegated plants will throw out a few solid-green leaves because, genetically, a lack of pigment isn't such a good thing for the plant. Variegation is the result of absent or masked green chlorophyll, and since it's the chlorophyll in the pigmented foliage that captures and transforms light energy into plant food, no wonder the plant struggles to return to its original form.

This is a much-simplified explanation of the genetics involved, but it also explains why variegated plants are usually not as vigorous as plants with uniformly green or solidly colored pigmentation.

At least it's easy to deal with this lack of stability in plant coloration. Just prune any reverted foliage as far back as possible as soon as you notice it. Because the all-green leaves and shoots are more vital, they will grow to dominate the plant if you leave them be.

Q: I was excited to read that the camassia is a Northwest native. Are there other bulbs native to the Northwest?

A: Yes, including graceful Erythronium oreganum and Erythronium revolutum with mottled leaves and drooping bell-shaped flowers. Native tiger lilies (Lilium columbianum) and native wild onions (Allium species) are easy-care and showy. Then there's the tall and wiry Brodiaeas, also known as blue dicks.

Unfortunately, native bulbs can be hard to locate — probably the best place to find them is at the Washington Park Arboretum annual bulb sale in early October and the Washington Native Plant Society sale. Check out its Web site (www.wnps.org) for sale dates and more information about all-too-often overlooked native bulbs.

Q: I am attempting to battle smartweed in two gardens. It is winning handily. I haven't used any herbicides in 25 years, but I'm getting close here. I have about three-fourths of an acre infested now where I plant veggies yearly.

A: Smartweed (Polygonum hydropiper) is variously known as water pepper, pepper plant and lady's thumb. Would it help you to know that the weed taking over your garden has a long medicinal history, used for colds, coughs, epilepsy and to get rid of fleas? Probably not too comforting. ...

While there seems to be universal agreement that smartweed is difficult to eradicate, I can find little information on effective methods to at least try. After thorough weeding, two inches of mulch seems to discourage seeds left in the soil.

Burning stubborn weeds with a propane torch works surprisingly well, although some broadleaf weeds need to be sizzled twice. I have to admit I've never attempted to burn out anything close to three-quarters of an acre of weeds. I suggest you contact King County Master Gardeners for their suggestions at 206-296-3440. Good luck.

Valerie Easton also writes about Plant Life in Sunday's Pacific Northwest Magazine. Write to her at P.O. Box 70, Seattle, WA 98111 or e-mail planttalk@seattletimes.com with your questions. Sorry, no personal replies.