Jim Teiber, city arborist, stands near an ash tree at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

The sign for the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Jim Teiber, city arborist, walks at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Jim Teiber, city arborist, stands near a European beech tree at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Alex Schuster (left), owner of ASE Illini-Scapes, and Jim Teiber (right), city arborist, unwrap trees for planting at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Alex Schuster (left), owner of ASE Illini-Scapes, moves a tree for planting at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Jim Teiber, city arborist, talks about the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Jim Teiber, city arborist, talks about the Joliet Arboretum next to a horse-chestnut tree Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Flowers on a horse-chestnut tree are visible at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Jesus Quintana (left) and Alex Schuster (right), owner of ASE Illini-Scapes, plant a bur oak tree at the Joliet Arboretum Wednesday, April 25, 2012, at 920 N. Broadway in Joliet. | Matthew Grotto~Sun-Times Media

Joliet Mayor Thomas Giarrante (second from right) and Chicagoland Speedway's Dash (far right) join third-graders in planting a Ginkgo tree at River View Elementary School Thursday, April 26, 2012, at 2097 Bronk Rd. in Joliet. Chicagoland Speedway, ComEd and Field's Nursery donated trees in honor of Arbor Day. | Matthew Grotto~Sun-Times Media

Music teacher Patti Czarnecki (at right) leads third-graders during a song during a tree-planting ceremony at River View Elementary School Thursday, April 26, 2012, at 2097 Bronk Rd. in Joliet. Chicagoland Speedway, ComEd and Field's Nursery donated trees in honor of Arbor Day. | Matthew Grotto~Sun-Times Media

ComEd forester Patrick Murphy (at left) designates where to place dirt as third-graders plant a Ginkgo tree at River View Elementary School Thursday, April 26, 2012, at 2097 Bronk Rd. in Joliet. Chicagoland Speedway, ComEd and Field's Nursery donated trees in honor of Arbor Day. | Matthew Grotto~Sun-Times Media

Ed Forneris (in bucket), with Asplundh Tree Expert Co., takes a picture of third-graders and staff during a demonstration of equipment as part of a tree-planting ceremony at River View Elementary School Thursday, April 26, 2012, at 2097 Bronk Rd. in Joliet. Chicagoland Speedway, ComEd and Field's Nursery donated trees in honor of Arbor Day. | Matthew Grotto~Sun-Times Media

Joliet Mayor Thomas Giarrante (at left) reads an Arbor Day proclamation during a tree-planting ceremony at River View Elementary School Thursday, April 26, 2012, at 2097 Bronk Rd. in Joliet. Chicagoland Speedway, ComEd and Field's Nursery donated trees in honor of Arbor Day. | Matthew Grotto~Sun-Times Media