﻿THE F ERN BU LLETIN 



Vol. XVi OCTOBER, 1908 No. 4 



NOTES ON SOME HYBRID FERNS. 



By Margaret Slosson. 



When the hybrid fern Dryopteris cristata x mar- 

 ginalis was first described, * it had been found only 

 with a caudiciform rootstock, like that in D. mar- 

 ginalis, that is, a rootstock of upright growth, capped 

 by a central crown. This character was supposed to 

 be always dominant in the cross. It appeared in both 

 of the two plants I obtained by artificially crossing D. 

 cristata and D. marginalis, f which corresponded with 

 the wild hybrid in all other respects as well. 



Now, however, it is certain that a decumbent, creep- 

 ing rootstock, like that in D. cristata, does sometimes 

 occur in plants of this hybrid. It seems the exception, 

 far from the rule, but I have seen it repeatedly in plants 

 taken from different parts of a large swamp in Pitts- 

 ford, Vt. In the plants that have it, the influence of 

 D. cristata seems more marked than in those with the 

 caudiciform rootstock; often the fertile leaf's pinnae 

 appear farther apart and the leaf's apex is more abrupt, 

 the leaf's general outline suggesting that in D. cristata 

 x spimdosa intermedia (D. Boottii) ; the leaf's texture 

 also, is perhaps slightly thinner, giving a slightly more 

 lax appearance to the plant. But these differences are 

 scarcely noticeable. It is possible, of course, that those 

 plants with the creeping rootstock may be the result 

 of a cross between D. cristata x marginalis and pure 

 D. cristata, or that they may be offspring of D. cristata 



*Bot.Gaz. 19: 497; 1894. 



T See "FemworA Papers," 24; 1900. Leaves from these plants are in the Herbarium of the 

 New York Botanical Garden. 



