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the ruling principle of botanical nomenclature when he said that 

 for every plant there can be but one name and that is its oldest if 

 tenable. This is merely a statement of a common law and com- 

 mon sense principle of every day application. We may add that 

 this principle applies equally to the generic and specific name of 

 a plant. Changes become necessary as our intimate knowledge 

 both of botanical literature and of the plants themselves widens. 



Considerable disturbance was manifested some years ago 

 among fern lovers because the name more familiar to the present 

 generation of Americans as Aspidium had been dropped for the 

 earlier name Dryopteris; and now Mr. Druery laments because 

 we do not use the name Lastrea for these plants as they do in 

 England, surely forgetting that at Kew, the center of English fern 

 study for three-quarters of a century, they use none of these names 

 but instead, a fourth name, Nephrodium ! Besides this Mr. 

 Druery incorrectly speaks of the use of Dryopteris as *' recent" 

 and as originally "American." 



The common shield ferns or buckler ferns or better wood 

 ferns now so variously known in different quarters as Dryopteris, 

 Aspidium, Nephrodium, or Lastrea, were known to Linnaeus as 

 species of Polypodium, since the generic characters derived from 

 the growth of the stipe from the rootstock, as well as those drawn 

 from the indusium, were not understood in his time. Adanson in 

 1763 was among the first to recognize the latter characters and he 

 established several new genera, among which was the genus 

 Dryopteris, which he characterized as follows: " Paquet de fleurs 

 rond, disposes sur 2 rangs sous chaqiie division des feuilles. En- 

 veloppe enparasol. Globules environnes d'un anneau elastique." 

 For a representative of this genus he cites (in his index) the 

 figure of " Filix-mas" given by Tournefort (1700) of the common 

 male-fern of Europe. 



Now this is absolutely the first generic name given to a mem- 

 ber of this group of ferns; it is clearly characterized, firmly 

 anchored to a type species, and there i^ no reason why it is not 

 " tenable." Other genera established by Adanson in the same 

 volume have never been questioned ; among these are Castanea, 

 Asimina, Poly gonat inn, Talinum, Paronychia, Nclumbo, 

 Pulsatilla, and Sabbat ia, some of them at least being names 

 familiar to those who know our' common flowering plants. 



If, therefore, all the ferns with a superior umbrella-like indu- 

 sium and roundish sori are to be included in one genus, that genus 



