26 FLORA OF WASHINGTON AND VICINITY. 



tive spot Sarraccnia purpurea^ Viola lanceolata^ and Carex hullata^ the 

 two first wholly unknown elsewhere, have been discovered ; a marsh a 

 mile above Bladensburg, near the mill-race, where only the majestic 

 Stenanthium rohustum has been seen; a little swamp near the Sligo 

 Creek, between the Kiggs and Blair roads, where the Hartford Fern 

 (Lygodium palmatum) grows sparingly; and another, between Bladens- 

 burg and the Maryland Agricultural College, where Solidago elliptlGa, 

 Ascyrum stans, and Lycopodium complanatum, var. Sabinwfolium, have 

 been found. The Eastern Branch region is not specially rich in floral 

 treasures, but on its banks and marshes some good things appear. 

 Steironema lanceolatum, Eleoclmris quadrangulata, ^cirpus JluviatiUs and 

 S. sylvatieiis, Ranunculus amhigens, and Salix Busselliana are among 

 these, though some of them are also found elsewhere. 



V. FLOWERING TIME OF PLANTS. 



It has already been remarked that most species flower at Washington 

 much earlier than at points farther north or than the dates giv^en in the 

 manuals. In consequence of this, a botanist unacquainted with this fact 

 and accustomed to those climates, and to relying upon the books, would 

 be likely to be behind the season throughout the year and fail to get 

 the greater part of the plants he desired. With all my efforts to make 

 allowance for this fact, I have frequently been sorely disappointed, and 

 was at last driven to making a careful record, preserving and correcting 

 it from year to year, of the flowering time of plants in this locality. 

 The notes on this subject appended to nearly every species enumerated 

 in the list embody the general results of these observations, and may in 

 the main be relied upon. The expressions used are not loose conjectures, 

 but are in the nature of compilations from recorded data. In most cashes 

 an allowance of two weeks may be made for the difference in seasons, 

 though rarely more and often less. Certain plants, as, for example, 

 Tipularia discolor, flower at almost exactly the same time every year. 

 Occasionally, however, one will vary a month or more in a quite unac- 

 countable way. But any one who has watched the periodical changes of 

 the general vegetation for a series of years and recorded his observations 

 will more and more realize the exactness even of these complex biological 

 phenomena, which depend so absolutely upon uniform astronomical 

 events. 



From this point of view the season which presents the greatest varia- 

 tion, and also for this and other reasons the greatest interest, is the 



