One of the hybrids in Dryopteris 
MARGARET SLOSSON 
In a recent number of the BULLETIN oF THE TorREY Boran- 
ICAL Crus* Mr. Ralph C. Benedict cites fifteen crosses as occur- 
ring between the following six of our species of Dryopteris: D. 
cristata, D. Clintoniana, D. Goldiana, D. marginalis, D. spinulosa, 
and LD. intermedia, Twelve of the fifteen hybrids have been 
described already.+ Two are held for further study. The one 
remaining, D. Clintoniana x marginalis, is the subject of this paper. 
This group of hybrid ferns is a difficult one, and plants are 
often found that are by no means easy to identify. This is partly 
due to our lack of knowledge of the range of variation normal to 
some of the parent species, or to be found in the different hybrids. 
D. cristata x marginalis, one of the best known and most com- 
mon members of the group, appears to have a perfectly definite 
range of variation. It is impossible to say at present whether this 
is true of the others or not. Few have been collected in sufficient 
quantities to justify a conclusion. Most of them represent problems 
to be worked out. 
The case is simplified by the fact that as a rule, at least, either 
the sporangia of these hybrids are abortive, or the spores, if present, 
are abnormal, and fertile hybrids, etc., are thus not likely to occur 
and confuse the outlook. Perhaps an exception to this may be 
found in D. cristata x intermedia (D. Boottit). Certainly the 
many plants of this hybrid, which occur so often, seem to indicate 
either a much more frequent hybridization than would be supposed 
probable, or some means of reproduction of the hybrid, perhaps 
asexual growth of some kind. 
Dryopteris Clintoniana x marginalis 1 collected first at Pitts- 
ford, Seront. in 1897, and again several times since then in 
*36: 4I- 1909. 
Tt See Bull. Toney Club 35: 135-140. 1908; 36: 41-49. 1909. —Rhodora6: 
75-77. 1904. — Bot. Gaz. 19: 492-495. 1894. 
201 
