28 THE PLANT WOELD 



summits are foiTiid the cespitose clumps of Diapensia lapponica L., Are- 

 7\aria Groenlandica Spreng, Vaccinium vitis-idaea L., while patches of 

 less dense character consist of the alpine willow, Salix uva-ursi Pursh., 

 PotentiUa tridentata Ait., Solidago virgaurea L., var. alpina Bigel., Ledum 

 latifolium Ait., Empetrmn nigrum L., Lycopodium lucididum Michx., Rho- 

 dodendron lapponicum Wahl, and the single specimen of Picea nigr-a, 

 Link. Growing as individuals in the alpine garden were found Pre- 

 nanthes Bootii A. Gray, Gornus Canadensis and PotentiUa tridentata Ait. 

 Upon the rocks of the highest summit were gathered CImloniarangiferina, 

 Oladonia coccinea, Umbilicaria sp., BuelLia sp., a yellowish green lichen 

 appressed to the surface of the granite rocks. 



It should be noted before closing this account that species, such as 

 Gorans Canadensis L., that were in fruit on the lower slopes of the moun- 

 tain were in full bloom on the summit. This is a fact of general import 

 where one is dealing with the altudinal distribution of plants. Plants 

 also, like Arenaria Groenlandica Spreng., and Gornus Canadensis L., 

 became dwarfed in habit as the higher elevations of the mountain are 

 reached, until they may be only an inch or two high, with more highly 

 colored flowers than the corresponding plants of the lowlands below. 

 University of Pennsylvania, Philadelphia, Pa. 



ANOTHER TRIP TO GLEN BURNIE, MARYLAND. 



By C. E. Waters. 



ME. PLITT'S article in the November number of the Plant Wokld 

 was read with much interest, for the pond and the surrounding 

 woods form one of my happy hunting grounds. I am not the 

 " Mr. W.," with whom he went, although we have been tramping 

 together. This is written, not to show how much he overlooked, but to 

 indicate that two persons may go over the same ground and see quite 

 different things. I have never seen the Habenaria tridentata, or H. cil- 

 iaris, the Glitoria, or Sahbatia, the Eryngium or the Discopleura. 



Perhaps, it is not quite fair to call this " another trip," for I am 

 going back over a series of trips, and shall pick out here and there 

 things of interest. 



Near that old furnace is a tiny stream so filled with Marchantia, 

 that the thalli stood on edge usually. There we found Pellaea atropur- 

 purea in abundance in the crevices of the furnace and on an old wall 

 nearby; a strange phenomenon, for the nearest plants growing on rocks 

 are miles away. This furnace is on the sandy Coastal Plain, within a 

 few feet of tide-water. Going back to the pond we cross woods, where 



