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planted along the Brook (toward the south) in order to secure the 
streamside conditions of a natural habitat. 
Dicotyledons with Separate Petals (Polypetalous) 
The plants in all the Orders on the east side of the Brook, be- 
ginning with the Magnolias (Magnoliaceae) and proceeding down 
through the Garden to the Dogwoods (Cornaceae), have flowers 
with separate petals, usually in 5’s, less commonly in 4’s. 
From north to south one passes, in succession, important groups 
such as the Buttercups and their relatives, Poppy, Mustard, Hy- 
drangea, Rose, Pea, Maple, Linden, Aralia, Dogwood, and others. 
Dicotyledons with Petals More or Less United (Sympetalous) 
After the Dogwoods (noted above), the plants of the remaining 
Orders of Dicotyledons—Heath Order (Fricales) to Bellflower 
Order (Campanulales)—have flowers whose petals are more or 
less united. 
The Heath Order, including Azaleas, Rhododendrons, Mountain 
Laurel, Heather (Calluna), Heath (Erica), and others, is on 
Azalea Knoll and Azalea Bank, at the extreme south end of the 
Systematic Section. 
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 famulies, including such 
forms as the Daisy, Burdock, Dandelion, and their relatives and, 
among cultivated plants, the numerous horticultural varieties of 
Chrysanthemum, Hardy Aster, Dahlhas, and others. : 
There are only a few woody genera of Composites with species 
hardy in this climate. A woody Chrysanthemum (C. nipponicune ) 
may be seen in the Rock Garden. Artemisia austriaca and A. 
procera, and the Groundsel Tree (Saccharis halimifolia) form 
hedges at the north edge of the Compositae area. 
The Dicotyledons terminate opposite the Rock Garden, and are 
separated from the Monocotyledons (on the north) by an area re- 
served for special plantings. 
