366 BOTANICAL GAZETTE [MAY 
each sporophyte appeared to be entirely independent of that of its twin 
except in the loose tissue forming the base of the haustra, where the line 
of separation was not clearly recognizable in all sections. In the region of 
contact, the epidermis, while quite distinct, was less strongly developed 
than on the free faces. Since the sporophytes were nearly mature at the 
time of collection, it was impossible to determine the conditions which led 
to the production of twins. It is probable that two functional oospheres 
were produced in the venter of each archegonium, although it is not impos- 
sible that twinning took place through an early branching of the young 
protocorm.—HaAroip L. Lyon, University of Minnesota. 
ADENODERRIS, A VALID GENUS OF FERNS. 
(WITH TWO FIGURES) 
THE genus Polystichum,! typified by the well-known P. Lonchitis 
constitutes a natural and well-defined group of ferns and has commonly 
had general recognition, recently even by American writers.? Its species 
are characterized, briefly, by their rigidity and erect habit, smooth firm 
dryish texture, mainly auriculate and spinulose or mucronate divisions, 
abundant chaff, free venation, and ordinarily by the orbicular centrally 
peltate indusia. The genus was divided by Jon SmirH into two sections: 
the one, typified by P. aculeatum and P. Lonchitis, with fasciculate generally 
erect acaulose vernation; the other, typified by P. coriacewm, with uniserial 
sarmentose vernation. In view of that writer’s natural bent for generic 
Segregation along the very lines on which the species of this genus were 
placed in two sections, it would not have been surprising if he had accorded 
to each section generic rank. That such a disposition—in view of the two 
radically different types of vernation—was not made is significant, for it 
emphasizes Smiru’s belief that in other respects the species are in too close 
agreement to warrant their division into two genera. There is, however, 
variation in one other particular; in certain species of both groups the 
indusium is caducous, or, as in P. tenue,3 apparently quite wanting; but 
even in these cases the appearance of the plants is so unmistakably that 
of Poly stichum and their agreement in the main particulars so essential 
that a rational course seems to necessitate their recognition as true mem 
bers of the genus. We have thus a group of species which, though offering 
? Rorg, Teut. Fl. Germ. 3:69. 1800. 
2 GILBERT, in papers presented at the Boston Meeting (1898), 22. 1899. UNDER 
woop, Our native ferns, ed. 6, 11 5. 1900. DAVENPORT, Rhodora 4:9. 190?) etc. 
3 GILBERT, Fern Bull. 8:63. rg00. 
Ne ee Dg RS CE ee, pay eS ee ee a cee sa 
