By Lynne Adkins

PHILADELPHIA (CBS)  —  People from all over the country are in Philadelphia this week to learn all they can about poison ivy.

The 4-day conference at the Horticulture Center in West Fairmount Park will explain the new rule of thumb for spotting the annoying plant according to expert Umar Mycka.

He says, the old saying is leaves of three let it be, the new saying is leaves of three resemble me.

That means, those leaves of three are going to have a head like we have, a neck and two arms connected to a body.

Participants will find out the best way to remove the plant and its roots, keep protected from the rash and find out poison ivy can live up to 30-years, and can grow to more than 3-hundred pounds.