7 



I find a similar state of affairs to exist in the true sensitive 

 plant (Mimosa pudica) of the Tropics. The leaves of this plant 

 droop and close instantly upon being touched, appearing" to melt 

 down like snow before a lire. Pressing the plant for the her- 

 barium is a difficult matter on this account. By the time one 

 has broken off a branch, every leaf has closed. After carrying 

 my specimens for some distance, however, I was surprised to 

 find that they were becoming resigned to the situation and again 

 opening their leaves. Putting them in the press gave them a 

 new and different shock and they " melted " again before the 

 straps on the press could be tightened. 



Our roadsides, river banks and old fields are strewn thick 

 with the common evening primrose (Oenothera biennis), but we 

 search in vain for specimens of its daylight counterpart, the sun- 

 drops (O. fnttieosa), which the Manuals persist in calling com- 

 mon. It is not unknown in southern New York, but in my 

 immediate vicinity it is entirely absent. One must see the two 

 species blooming together to realize how superior to the evening- 

 primroses are to those which flower by day. 



Until last year we had been looking for the dwarf sumac 

 (Rhus eopallina) without success. "Rocky hills," says Gray's 

 Manual, indicating its habitat, but here, where rocky hills are 

 at a discount, it is exceedingly rare. It may be noted that it 

 does not appear to be restricted to rocky places, for it grows 

 abundantly in the sandy soil of Long Island. In any event, it 

 is rare with us. I know of only one clump in a territory of more 

 than five hundred square miles. 



The list of species which it would seem ought to be plentiful 

 in the Susquehanna valley, but which are not, is a long one, and 

 includes such common plants of other localities as the whitlow- 

 grass (Draba verna) rock rose (Helianthemum canadense), the 

 pinweeds (Leehea), of which not a specimen is to be found in 

 certain counties ; the Aretluisci and the painted cup (Castilleia 

 coccinea). The whole area drained by the Upper Susquehanna 

 has been sufficiently explored to assure us that these plants are 



