Poison ivy — two words that strike fear into gardeners' hearts.

We all know it's lurking out there, but many of us don't think we can catch it, so we don't learn how to avoid it.

"Most people think that they are not allergic to poison ivy because they have never developed a rash from the plant. This is usually a misconception based on a lack of significant exposure," says Susan Pell, a molecular plant systematist and laboratory manager at the Brooklyn Botanic Garden. "All people should take caution with this plant and its other toxic relatives."

Pell — who holds a Ph.D. in plant biology and has done extensive research on the cashew family, which includes poison ivy, poison oak and poison sumac — says you don't have to be a botanist to learn how to identify these plants.

"Poison ivy has several features that make it unique in the Northeastern flora," Pell says. "Once you learn the characteristics of the leaves, fruit and stems, contact with poison ivy can be avoided in every season."

Pell offers these suggestions on poison ivy:

• Identification: three leaflets ("leaves of three, let it be"), turn red in fall; reddish stems, climbing stems (on tree trunks etc.) are covered in many reddish roots in all seasons; fruit ("berries" — actually classified as drupes by botanists) is white.

• Before exposure: use Ivy Block (two-fold prevention: It makes poison ivy's urushiol (sap) inactive by binding to it and also provides a barrier to the skin) and wear long sleeves, pants and gloves.

• After exposure: Wash with cold water (warm water can spread urushiol), and wash your clothes and equipment right away.