THE STRUCTURE AND LIFE-HISTORY OF THE HAY-SCENTED FERN. 



By HENRY SHOEMAKER CONARD, 

 Professor of Botany, Iowa College. 



HISTORICAL INTRODUCTION. 



The hay-scented fern, Dennstcedtia punctilobula (Michx.) Moore (= 

 Dicksonia punctilobula Willd.) first appeared in botanical literature in 1803, 

 when it was described by Michatix as follows: 



\Nephrodium~\ punctilobulum. N. majusculum: stipite nudo, ramis pinnulisque pu- 

 bescentihus: fronde longa, bipinnata; pinnulis decurrentibus, subovali-oblongis, semi et 

 ultra pinnatifidis; lobulis oblonguisculi, apice 2-4-dentatis, singulis unipunctiferis. Obs.: 

 Habitus Polyp, filicis fceminas Linn. Hab. in Canada. [A. Michaux, 1803, p. 268.] 



There is nothing- in the text to indicate that this is a new species. 

 Michaux' s genus Nephrodium was extremely far-reaching', being: defined 

 in these words: "fructibus punctis subreniformibus" (p. 266). Among 

 the species are N. thelypteroides, marginale, filix-ftzmina, and dryopteris! 



Swartz (1806) placed the hay-scented fern in the genus Aspidium, in 

 which he was followed by Willdenow (1810). The latter writer, both in 

 his own text and in his quotation from Michaux, changes the spelling of 

 the specific name to punctilobum. But he had already (1809) described it 

 under the name of Dicksonia pilosiuscula, and this, too, is copied in the 

 Species Plantarum. The text of the Enumeratio (1809) is as follows: 



DICKSONIA. 



Sort subrotundi distinct! marginales. Industum duplex, alterum superficiarum exte- 

 rius dehiscens, alterum e margine frondis inflexo interius dehiscens. 



i. 



D. frondibus bipinnatis, pinnis pinnatifidis, laciniis dentatis, rachi pilosiuscula. 

 Polypodium pilosiusculum. Miihlenberg in litt. Habitat in Pennsylvania. (!) 

 Q[D. 



An important addition to the other diagnosis is the notice of hairs upon 

 the rachis. These are so characteristic as readily to distinguish this fern 

 from any other in our native flora. In preparing the ' 'Species' ' , Willdenow 

 recognized the similarity of his Aspidium punctilobum and Dicksonia pilosius- 

 cula as expressed in the closing words of the description of the latter : 



An Aspidium punctilobum supra p. 270 dubie indicatum, eadem sit filix aliis ad 

 dijudicandum relinquo? quum pinnulas neque sint decurrentes neque pubescentes. 



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