There are many types of ivy, from English ivy (which you can also grow indoors), to the true ivy's close relative, poison ivy, which is famously irritating, causing a terrible, itchy rash. Ivies are evergreen, which means they keep their green leaves in the winter. The so-called "Ivy League" is a group of eight selective colleges (including Harvard and Princeton), given this name for the ivy that creeps up many of the campuses' old brick buildings.