THE ROCK SPLEENWORTS. 171 
species produces young fronds at the apex, but only rarely. 
In plants that have this tendency to be vivaparous, a sud- 
den check, as by cold, just as the fronds are fruiting, is 
said to greatly increase it. In cultivation the produc- 
tion of young plants in this way is much more common 
than when they are growing wild. The sori are seldom 
plentiful and are borne in a double row on each pinnule 
and open toward the midvein. The spores are frequently, 
perhaps always, abortive. 
This species has been reported from stations in Ver- 
mont, Connecticut, New York, New Jersey, Pennsylvania, 
Virginia, Illinois, Indiana, Kentucky, Missouri and Ala- 
bama, but the records usually rest upon very few speci- 
mens, often only one. So far as known, there is only one 
locality where it is plentiful—a deep ravine near Havana, 
Alabama. 
Prof. Underwood who collected it in this spot writes as 
follows concerning it. “Its nearest congener is As- 
plenium pinnatifidum but the frond is much thinner than 
in that species. In habitat, however, it is very close to 
that species, growing under overhanging rocks; in this 
respect it is totally unlike both A. ebeneum and Camp- 
tosorus, its supposed parents. It appears to be multiply- 
ing, as many young plants were seen in the rock crevices. 
This myth of hybridity may be put aside, for Asplenium 
ebenoides is as clearly defined a species as we possess in 
the genus Asplentum and has no near relatives outside 
its own genus.” The plant figured was collected by 
Prof. Underwood at the Alabama station. 
There are two other spleenworts for which a place is 
sometimes claimed among American ferns, though the 
proof of their occurrence in this country rests upon 
