PHILOSOPHICAL SOCIETY OF WASHINGTON. 85 



Thalictrum dioicum, April 14, 1876. 



Rhus aromatica, April 14, 1878. 



Phlox subulata, April 14, 1878. 



Arab is patens, April 18, 1880. 



Cardamine hirsuta, var sylvatica, April 18, 1880. 



Negundo aceroides, April 18, 1880. 



Erigeron bellidifolius, April 18, 1880. 



Krigia Virginica, April 18, 1880. 



Sisyrinchium Bermudiaua, April 18, 1880. 



Carex laxiflora, April 18, 1880. 



Carex Emmonsii, April 18, 1880. 



Melica mutica, April 18, 1880. 



Anemone nemorosa, April 19, 1874. 



Viola cucullata, var. cordata, April 19, 1874. 



Dirca palustris, April 19, 1874. 



Carex Pennsylvanica, April 19, 1874. 



Lathyrus venosus, April 21, 1878. 



Ribes rotundifolia, April 21, 1878. 



Salix nigra, var. Wardi, April 21, 1878. 



We thus see that a single collector has in the course of eight year's 

 operations actually observed and noted eleven species in bloom in 

 February, 24 more in March, 51 additional in the first week of 

 April, and 26 others during the second and third weeks of April or 

 112 up to April 21. 



It should be remarked that there is no doubt that if the same lo- 

 calities in which the large numbers were observed on April 2 1876, 

 April 4, 1880, and April 7, 1878 had been visited in the last days of 

 March of those years quite a number of these plants would have 

 been found sufficiently advanced to demand a place in the lists, and 

 thus the month of March would have been credited with so many 

 here set down for the first week in April. Probably, all things 

 considered, not less than fifty species in certain favored seasons 

 either reach or pass by their flowering-time by the end of March. 



In arranging the above lists the order of dates has of course 

 taken precedence, but where several are enumerated under one date 

 the natural order is followed. 



It is scarcely necessary to suggest a caution to collectors against 

 relying upon these dates in making collections. They represent 

 the earliest observations and not the average. In most cases an 

 allowance of at least one week should be made for the full bloom- 



