June, 1910.] Winter-Buds of Spirodela. i8i 



The ordinary Fragile Bladder Fern grows in abundance upon 

 these rocks. A hasty glance revealed the fact that it differed 

 very materially from the ordinary form. The apexes of the frond 

 and the tips of the pinnae are branched two to four times, acumi- 

 nate, obtuse or emarginate. 



The plant grows plentifully in the partially shaded ravine 

 and the differences from the normal type of frond seem to warrant 

 the name: 



Cystopteris jragilis (L.) Bernh. var. cristata Hopkins, var. nov. 



Apex of frond branched, the branches often dividing again; 

 obtuse or acuminate, pinnae linear, lanceolate, broadly triangular, 

 acuminate, acute or obtuse often branching into two or more irre- 

 gular segments; in part on sandstone rocks, Woodworth's 

 Glenn, Portage County, Ohio. (Fig. 2). 



Pittsburgh High School. 



WINTER-BUDS OF SPIRODELA POLYRHIZA (L.). 



V. Sterki. 



Last summer and fall, I brought home several kinds of 

 "duckweeds," and kept them in aquaria, some of the latter being 

 small tumblers. During September and October it was noticed 

 that there were numerous small disks, or links, partly free, partly 

 connected with Spirodela plants. They were flat, short-elliptical 

 or oblong, or nearly circular, of about one to two mm. diameter, 

 of a deep green color (darker than the spirodela disks), always 

 rootless, without any visible venation and with a small, sharply 

 defined, crescent-shaped, whitish to brownish hilum at the margin. 

 Microscopic examination, made in February, showed them to 

 have stomata on the upper surface and a slight but distinct 

 purplish hue on the lower, inside of the epidermis. 



With the approach of winter, the Spirodela plants faded 

 and died, but these small bodies kept fresh and green, and most 

 of them sank to the bottom. vSome, however, were kept floating 

 by the dead disks, now little more than skeletons. Some were 

 seen as late as February, each being held between the two epi- 

 dermal layers of its parent disk, near the hilum, partly emerging 

 from the margin. Several score were in a small tumbler aqua- 

 rium, near a window but not reached by direct sunlight until the 

 end of winter. During the latter part of January, and up to 

 the present it was noticed that each had a small gas bubble on 

 its upper surface, probably oxygen, and some were raised to the 

 surface by the same and kept floating. Many of them are now 

 sprouting, at the hilum, while others are still at the bottom, 

 unchanged. Another such small aquarium, with Lemna tri- 



