PREFACE. 



r I IHE County of Nantucket comprises the islands of Nantucket, Tucker- 

 nuck and Muskeget, and a small group called Gravelly Islands. A 



JL list of their plants, including the marine algae growing in the sur- 

 rounding waters or washed up on their shores, is attempted in the following 

 pages. The islands are separated by channels from an eighth of a mile to 

 half a mile in width, and may be considered geologically as but one. This 

 island county is part of the extreme terminal moraine of the ice-sheet that 

 covered the northern part of our continent during the glacial period, and is 

 a series of morainic hills bordered on the south by sloping plains of gravel 

 and sand. The hills are from forty to fifty feet high at Madeket, at the 

 west end of Nantucket, and sink lower from there to Muskeget, while they 

 rise towards the east. They reach the height of 91 feet in the highest of 

 Saul's Hills, and of 105 feet at Sancoty Head, the highest land on the island. 

 The formation is almost wholly stratified gravel and sand, deposited at the 

 margin of the ice by streams that flowed down from its surface; but in the 

 region of Saul's Hills, bowlders are scattered upon and in it, varying from 

 a small size up to ten feet in diameter. The pine barrens, although farther 

 south, are of similar structure, and Nantucket, as regards its flora, seems 

 like a piece of New Jersey moved up the coast for the convenience of north- 

 ern amateurs in botany, who cannot get away from business long enough to 

 go collecting in that state. 



The writer has not been able to obtain any report of the productions of 

 Muskeget and Gravel uninhabited islands and Mr. L. L. Dame has ran- 

 sacked Tuckernuck without finding anything new ; the most noticeable thing 

 was the quantity of a common milk- weed (Asclepias obtusifolia), which was 

 growing more profusely than he had ever seen it in any one locality before. 

 What follows, then, relates solely to Nantucket, the large island of the 

 county, with an area of about fifty square miles. 



The winters there are mild, and snow seldom lies long on the ground, so 

 that the hardier weeds, like groundsel and chick-weed, may frequently be 



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