The Morton Arb

Trees & Gardens

Use our Interactive Collections Map and our Plant Collections Map to identify where plants are located on our grounds.

Explore our Plant Database

Integrated data of The Morton Arboretum's living collections, herbarium, interactive collections map, and photographs. Search database

How Plants are Named
The words in the scientific name of a plant all mean something. Learn how plants get such interesting names. Click here

How To Read a Plant Label at the Arboretum

Plants of Acid Soils: Rhododendrons and Azaleas

Rhododendrons at the Arboretum

The heath (Ericaceae) family contains many highly ornamental garden plants including rhododendrons, azaleas, heaths, and heathers. Because the members of the family naturally occur in areas where soil pH is low (below 6.5), they are acidophiles, meaning acid-loving plants.

Plants of Acid Soils was established by modifying calcareous soils (typical in the Midwest) on the Arboretum grounds. The staff worked with the American Rhododendron Society, Midwest Chapter, to create a rhododendron test bed where many desirable and recommended varieties for this region are featured.

Rhododendrons and azaleas are the dominant group in this collection and are represented by over 67 kinds. Arboretum staff evaluate and promote desirable rhododendrons for Northern Illinois. The rhododendrons in this collection put on a spectacular display in spring.

In winter, the hollies (Ilex) steal the show with their evergreen leaves and bright red fruits. The blue hollies are extremely cold hardy and have lustrous dark green leaves, providing dramatic backdrops for their bright red fruits.