It was with great reluctance that the author undertook the work ; though he has, during the last seventeen years, botanized in the region, and has corresponded with and examined the collections of botanists who have visited parts of the territory not examined by himself ; yet he feels sure that there are plants growing in the limits which have not been noticed by botanists, or, at least, have not been reported.

He set out, however, with the determination not to include any in the list except such as he himself, or some one in whom he had full confidence, had seen growing in the county. As no one has examined

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INTRODUCTION'.

the region with the intention of publishing a report, until within the last two years, it is reasonable to infer that many plants will yet be found that are not included in this leport. The author has corresponded and held conferences with not only the botanists of the county, but with those of New York city.

The botanists of New York city are active, industrious collectors, and have absolutely exhausted most of the localities within walking distance of the city; especially such portions of New Jersey, Staten Island and parts of Long Island. The Harlem River, however, seems to have been, to a great extent, the limit to their excursions in this direction; hence, this county is less known to New York botanists than any other region within the same distance of the city. The collecting of information has, therefore, been more formidable than suspected.