March, 1922] BENEDICT — NEW VARIETIES OF NEPHROLEPIS I47 
time of the year is twice pinnate. The amount of reversion noted in the 
Childs plants referred to above is exceptional. Twice pinnate leaves are 
usually in the majority at all times of the year. That the divided-leaf con- 
dition is fixed is well illustrated by the experience with the Childs plants 
just related. Although externally those plants had lost all indications of 
the twice pinnate character, continued cultivation showed that it had been 
only temporarily obscured. It seems a safe conclusion that the actual 
basis of the original Piersoni variation from bostoniensis must have been 
a protoplasmic change which maintained itself even though temporarily 
not evident in the gross characters. 
The facts detailed thus far — the appearance of once pinnate leaves in 
Piersoni stock — represent no real regressive variation or reversion but rather 
fluctuation within the limits of the Piersoni type. There are, however, 
three possible types of unmistakable reversion which should be considered. 
The occurrence of a complete and discontinuous reversion to a once- 
pinnate form is highly probable. The fact that there is no record of such 
a reversion does not alter the probability. The florist would not be likely 
to detect its occurrence. Bostoniensis is almost invariably grown wherever 
any of its varieties are in cultivation, and the appearance of a once pinnate 
plant among Piersoni stock ordinarily would be passed over as a misplace- 
ment of a bostoniensis plant. As will be described below, this type of 
permanent reversion is well known in other varieties. 
Partial reversion to a condition of greater instability is postulated on 
the basis of the behavior of other varieties considered below. This change 
would result in a strain in which the number of twice pinnate leaves would 
be fewer than in the best strains. 
The most interesting reversion attributable to Piersoni, or, indeed, to 
any other bostoniensis variety, is a plant of the Piersoni type of division, but 
one the exact origin of which is unfortunately shrouded in doubt, I ob- 
tained it from the New York Botanical Garden where it was being grown 
under the name of a totally different variety and species, Nephrolepis 
hirsutula tripinnatifida. Its earlier history is unknown, but two explana- 
tions of its origin are possible. It may represent a progressive twice pinnate 
sport from wild fertile exaltata of which the New York Garden has plants 
from several collections in Porto Rico; or it may represent a reversion in 
fertility from some plant of Piersoni which has been grown there for the 
nineteen or twenty years since its introduction. The latter explanation 
seems the more probable. In any event, it is unique among Nephrolepis 
exaltata forms in its fertility, and a particular interest attaches to it in the 
possible type of its spore progeny of which several separate sowings are 
being grown and will be reported on later. 
Anna Foster (PI. V, figs. 7-12) represents a twice-pinnate form also in a 
^ For purposes of reference and discussion, I have assigned the name " fertilis" to this 
form. Technically its name should read, Nephrolepis exaltata bostoniensis var. fertilis. 
