FLORA OF WASHINGTON AND VICINITY. 17 



1,500 vascular plants. It would appear, therefore, that only a little 

 over half the plants actually existing were discovered by the botanists 

 of that day and enumerated in their catalogue. If the proportion of 

 disappearances could be assumed to be the same for species not discov- 

 ered as for those discovered by them, this would raise the aggregate 

 number to considerably above one hundred, perhaps to one hundred and 

 twenty-five. 



The great number of present known species not enumerated in the 

 Prodromus, some of them among our commonest plants, and amounting 

 in the aggregate to 535 species, is another point of interest, since, after 

 due allowance has been made for mistakes in naming them, it remains 

 clear on the one hand that their researches must have been, compared 

 with recent ones, very superficial, and on the other that, not to speak of 

 fresh introductions, many plants now common must have then been 

 very rare, otherwise they would have proved too obtrusive to be thus 

 overlooked. 



There are many other interesting facts growing out of a comparison 

 of these two remote dates, but space forbids their further discussion. 

 Anyone can pursue the subject who desires to do so, from the data 

 already given and to be given, or by consulting the Prodromus itself. 



IV. LOCALITIES OF SPECIAL INTEREST TO THE BOTANIST. 



The flora of a wild region is always more uniform than that of one 

 long subjected to human influences. The diversity in the former is a 

 natural consequence of the corresponding diversity in the surface and 

 other physical features. In the latter it is due to conditions arbitra- 

 rily imposed by man. A primeval flora is usually more rich in in- 

 digenous species, but the artificial changes caused by cultivation often 

 offset this to a great extent by the introduction of foreign ones. This, 

 however, greatly reduces its botanical interest. 



In many respects the botanist looks at the world from a point of view 

 precisely the reverse of that of other people. Eich fields of corn are 

 to him waste lands; cities are his abhorrence, and great open areas un- 

 der high cultivation he calls "poor country"; while on the other hand 

 the impenetrable forest delights his gaze, the rocky cliff charms him, 

 thin-soiled barrens, boggy fens, and unreclaimable swamps and morasses 

 are for hmi the finest land in a State. He takes no delight in the " march 

 of civilization," the ax and the plow are to him symbols of barbarism, 

 and the reclaiming of waste lands and opening up of his favorite haunts 

 Bull. Nat. Mus. No. 22 2 



