Nov., 1910.] A Floristic Survey of Orchard Island. 
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There is a sparse growth of shrubs, Rubus nigrobaceus, Rhus 
glabra, R. toxicodendron, Vitis vulpina, etc. The herbage is 
also poorly developed, it consists of a thin growth of grass and 
common weeds which have been frequently mowed and in some 
places burned. A narrow border of larger trees, remnants of the 
original forest, surrounds this central area. On the south and 
west this forest border is twenty to thirty feet wide; but to the 
north and east there is sometimes but a single tree, the lawns 
extending to the water’s edge. 
An interrupted zonation of swamp plants occupies the shallow 
water and the now exposed mud plain surrounding the island. 
The swamp is well developed on the west, south and southeast, 
but has been more or less completely cleared away in the vicinity 
of the docks on the north, northeast and east sides. 
This island exhibits a striking example of the invasion of plants 
into new areas, successful ecesis, the resultant succession, the con- 
sequent filling of the lake and the upbuilding of new land areas 
along the margin; and in the center a secondary succession in a 
partially denuded area. A detailed floristic study was made of a 
belt sixty feet broad and extending directly across the island from 
the southeast to the northwest, from a-a' to b-b' on the map. 
This belt covers a representative area of the island, including a 
section of the well developed marsh on the southeast, and on the 
northwest the marsh disturbed and reforming; a section of the 
older forest zone and of the rejuvenated central area. 
There are three distinct formations based on habitat and 
growth forms: 
I. The marsh-herb formation. 
II. The swamp-shrub formation. 
III. The mesophy tic-forest formation. 
The first and third formations are well developed, the first 
exhibits a striking lateral and vertical zonation, the second is so 
fragmentary that it can scarcely be dignified by the name of 
formation; but it is of interest as an illustration of the intrusion 
and development of a zone between two previously existing ones. 
I. The marsh-herb formation on the southeast: 
1. Nelumbolutea Society. 
Facies. 
Nelumbo lutea. 
The society forms a zone 20-40 feet broad. At the outer 
margin the water is 4-4.5 feet deep at the inner about 8 inches. 
Secondary species. 
Potamogeton pectinatus. 
Potamogeton var. 
Ceratophyllum demersum. 
Potamogeton natans. 
Cladophora sp. 
Spirogyra sp. 
