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Introduction. 



In presenting this Flora of Long Island the writer feels that a few 

 words of explanation will make it clear, why, in a region of which so 

 many local floras have been written, it has been deemed a matter of 

 sufficient interest to prepare a flora of the whole island. 



The reason lies in the peculiar features of botanical interest that are 



caused by the position of the island in relation to the mainland and 



the history of the growth of plant life on the Atlantic slope, as shown 



by the combined evidence of geology and botany on Long Island. To 



obtain a just conception of what these features of interest are a brief 



glance at the geological formation of the island, both present and past^ 



may be of service. 



Geology. 



It is well known that Long Island is a terminal moraine of the great 

 transatlantic ice sheet that stretched across the continent from Nan- 

 tucket, which may be considered to be the extreme southeastern limit 

 of the glacial action to Ohio and still further west.'^ F. J. H. Mer- 

 ttll has given a very excellent account of the geolbgy of Long Island 

 and his account is here freely used.f 



** Long ^Island is about 120 miles long and varies from a mile to 

 Miven or eight miles in breadth. As a whole it is comparatively low 

 *nd flat, but throughout there is a range of hills extending from its 

 extreme western end at Bay Ridge, which are a continuation from 

 similar hills of Staten Island, northeasterly to Roslyn and thence con- 

 ti«iuing to Montauk Point in a series of elevations, the most important 

 of which are known as West, Dix, Comae, Bald and Shinnecock Hills. 

 The average height of this chain is about 250 feet ; but at some points 

 it is greater. Harbor Hill at Roslyn is 384 feet above the tide ; 

 |ane*s Hill 383 feet, Reuland's Hill 340 and Wheatley's Hill is 369 

 feet above the sea. 



*^ There is also along the north shore an elevation which usually 

 follows the contour of the numerous bays and inlets, varying in height 



* Upliam, North American Ice Sheet, Amer, Jourtu Science^ 28, 1897, pp. 81-92 ; 

 Terminal Moraines of the North American Ice Sheet, Amer. Journ, Science^ III.^ 

 p. 18. 



•\ Ammk of the N, K AmdePHy of Science, 3, 1883-1885, pp. 341-3^4. 



