why is it called 'ivy league'?

Answer 1

The colleges so named are all the richest and oldest colleges in the land, and their buildings were brick and stone in the Northeast US covered with ivy plants.

When I was a child, I lived in Philadelphia and used to walk at University of Pennsylvania, one of the Ivy League, which had many ivy-covered buildings. Today, they have cut down all the ivy because it dislodges the mortar between the bricks and destroys the now-historic structures.

From the link below:
All of the Ivy League institutions share some general characteristics: they consistently place within the top twenty in the U.S. News & World Report college and university rankings; they rank within the top one percent of the world's academic institutions in terms of financial endowment; they attract top-tier students and faculty. Seven of the eight schools were founded during America's colonial period; the exception is Cornell, which was founded in 1865. Ivy League institutions, therefore, account for seven of the nine colleges chartered before the American Revolution. The Ivies also are all located in the Northeast region of the United States and are privately owned and controlled. Although many of them receive funding from the federal or state governments to pursue research, only Cornell has state-supported academic units, termed statutory colleges, that are an integral part of the institution.

Answer 2

WHAT THE GIRL SAID ABOVE SOUNDS GOOD!