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flower Order (Campanulales)—have flowers whose petals are 
more or less united. 
The Heath Order, including Azaleas, Rhododendrons, Laurel, 
Heather (Calluna), Heath (Erica), and others, is on Azalea 
Knoll and Azalea Bank. 
After the Heaths, the Orders of the Dicotyledons follow up the 
west side of the Brook, terminating with the plants whose flowers 
have petals united to form a bell-shaped floral envelope—the 
Campanulales, named from the Bellflower (Campanula). The 
chief family of this order is the Compositae, the most highly de- 
veloped of all the dicotyledonous plant families, comprising such 
forms as the Daisy, Burdock, Dandelion, and their relatives and, 
among cultivated plants, the numerous horticultural varieties of 
Chrysanthemum, Hardy Aster, Dahlias, and others. 
The Dicotyledons terminate opposite the Rock Garden, and 
are separated from the Monocotyledons (on the north) by the 
Ecological Garden. 
Monocotyledons 
All of the plants having embryos with one seed-leaf (Mono- 
cotyledons), and with petals (when present) in 3's, are north of 
the Ecological Garden and west of the Brook. They comprise 
the Lily, Iris, Canna, Grass, Orchid, and other Families. The 
Orchids are on the Border Mound, west of the paved walk. They 
are the most highly specialized of the Monocotyledons. 
The Monocotyledons appear to have descended from the Dicotyledons, the 
process involving various structural and anatomical changes, including the 
hereditary failure of one of the seed-leaves or cotyledons to develop, thus 
resulting in embryos with only one seed-leaf. 
Note that there are no monocotyledonous trees hardy in this 
climate, and only a few shrubs, such, for example, as Smilax. 
Ecological Controls 
In order to take advantage of the most favorable cultural con- 
ditions, and also for planting effect, the Irises (like the Willows 
and Poplars mentioned on page 178) are extended along the Brook, 
on either side. 
