414 BOTANICAL GAZETTE [DECEMBER 
in an ordinary species be designated as a “perfect frond.” Something 
of this tendency is occasionally seen in Asplenium pinnatifidum, but in 
A. ebenoides it is at once the most noticeable and constant feature. In 
its ordinary mature development it is as constant in this irregularity of 
shape as most ferns are in their symmetry; this in itself indicates an 
unusual phylogeny and is a strong bit of evidence supporting its claim 
to hybridity. A like trait has been noted” by Mr. Davenport in the 
case of his Dryopterts cristata X marginalis, which, it may be added, 
Miss Slosson’s recent experiments bid fair to prove a true hybrid.” 
It may be noted further that at Havana A. ebenoides in its habitat 
resembles neither of its supposed parents, both of which require con- 
siderable humus and grow mostly upon rocks. A. ebenoides, however, 
is here strictly a mural fern, and like A. pinnatifidum and Pellaea 
atropurpurea grows in the narrow chinks of rock where there is a mini- 
mum of earth. It is for the most part well shaded and must derive 
most of its moisture from the porous conglomerate cliff, on the under 
side of which it grows. The cause of its abundance here is undoubt- 
edly to be found in the especially favorable environment, and perhaps 
a greater fertility of spores than in the other stations. That it has not 
a wider distribution in the general region is no more remarkable than 
the limited distribution of other species, and is perhaps due to a dearth 
of suitable situations. But Professor Murrill’s observations upon the 
plants found by him in six or seven different localities near Blacks- 
burg, Virginia, show that the fern does well in light rich soil ; while a 
recent letter from Dr. Rusby states that the plants found by him” near 
Newton, N. J., grew in an open sunny spot on a dry limestone ridge ; 
so that after all its habitat is variable. Whenever A. ebenoides has been 
found elsewhere than at Havana it has usually, if not always, been a 
plant or two in a place, and these rarely in the same general region. 
What is there to account for this isolation? They might arise from 
wind-blown spores; but in this event is it not a singular coincidence 
that the fortunate spore happens on each occasion to settle between 
plants of Asplenium platyneuron and Camptosorus ? Besides, the sta- 
tions are mostly separated by considerable distances, one in Vermont, 
another in Connecticut, in New York, and so on. Thus, though it be 
a possible, we may hardly regard it as a probable means of origin. Is 
it not then somewhat plausible to suppose a local origin for the fern at 
‘7 Papers Pres. Bost. Meet. (1898), 10. 1899. 
* Fernwort papers. (Ined.) 19 Bull. Torr. Bot. Club 7: 29. 1880. 
