50 FLOEA OF WASHINGTON AND VICINITY. 



The Monocotyledons give us Ariscema triphyllum, the Indian turnip, 

 Sagittaria variabilis, Aplectrum fiyemale, Erythronium Americanum, Luz- 

 nla campestris, Juncus effusus, J. marginatus, and J. tenuis; Pontederia 

 cordata. Of the Cyperi, C. phymatodes, C. strigostis, and C ovularis are 

 the most common ; Eleocharis obtusa and E. paiustris, Scirpiis pungens, >S. 

 atrovirens, S. polyphyllus, and S. Eriophorum are very conspicuous. Of 

 Garices, C. crinita, G. intumescens, the various forms of G. laxijlora, G.platy- 

 phylla, G. rosea, G. scoparia, G. squarrosa, G. straminea, G. angustata, G. 

 tentaculata, G. virescens, and G. vtdpinoides are the most obtrusive. 



In the Graminew, those which most uniformly strike the eye are 

 Agrostis scabra, MuJilenbergia Mexicana, and 31. sylvatica; Tricuspis ses- 

 leroides, Eatonia Pennsylvanica, Poa pratensis, P. sylvestris, and P. brevi- 

 folia; Eragrostis pectinacea, Festuca nutans, Bromus ciliatus, Elymus 

 Virginicus, Dantlionia spicata, Anthoxanthum odoratum, Panicum virga- 

 tum, P. latifolium, P. dichotomum (with a multitude of forms), and P. 

 depauperatum ; Andropogon Virginicus and A. scoparius. 



Of ferns, Polypodium vulgare, Pteris aquiUna, Adiantum pedatum, 

 Aspleniuni ebeneum, and A. Filix-fcemina ; Phegopteris hexagonoptera, 

 Aspidiuni acrostichoides, A. marginale, and A. Noveboracense ; Osmunda 

 regalis, 0. Glaytoniana, and 0. cinnamoniea are the most constantly met 

 with. Lycopoditim lucidulum is quite common, and L. complanatum is 

 very abundant in certain localities. 



Besides the above, which are all indigenous to our flora, there are of 

 course many introduced species in the vicinity of the city and of culti- 

 vation everywhere, which manifest here as elsewhere their character- 

 istic tendency to crowd out other plants and monopolize the soil. 



Such are the most general features which the traveler, accustomed to 

 observe the vegetable characteristics of localities visited, may expect to 

 see when he pays his respects to the Potomac Valley. To some, even this 

 imperfect descrijjtion might furnish a fair idea of our floral scenery with- 

 out actually seeing it. 



XI. CLASSIFICATION ADOPTED. 



In endeavoring to conform to the latest authoritative decisions rela- 

 tive to the most natural system of classification, I have followed, with 

 one exception, the arrangement of the Genera Plantarum of Bentham 

 and Hooker, so far as this goes, and the accepted authorities of Europe 

 and America for the remainder. For the Ganiopetalce after Gompositce, 

 however, covered by Professor Gray's Synoptical Flora of North Amer- 

 ica, I have followed that work, which is substantially in harmony with 



