88 BOTAMCAL GAZETTE [july 



are two kinds of secondary vascular development; in the one case the 

 pericycle becomes meristematic and adds vascular elements to the stele; and 

 in the case of large roots this is followed by a similar behavior of the cortical 

 cells just outside the endodermis. In Pandanus and Yucca internal vascular 

 strands were discovered, which are differentiated at the growing point. In 

 the aerial roots of certain Araceae, inside of the radial primary vascular 

 cylinder, there occur scattered groups of xylem and phloem vessels. — J. M. C. 



Sex intergrades. — Yampolsky 7 has brought together the evidence of sex 

 intergrades in flowering plants. The discussion is based upon his results 

 with Merairialis annua, in which he had found sexuality to be a fluctuating 

 character. At the close of the paper he gives a long list of families showing 

 transition from the monoecious to the dioecious condition, and also tabulates 

 the results under 12 types. The general conclusion confirms the view that 

 the potentialities of both sexes exist in all plants, and are not localized in any 

 particular region or cells. — J. M. C. 



Endosperm development in Vaccinium. — Stevens 8 has described an 

 interesting case of endosperm development in Vaccinium corymbosum. Two 

 distinct types of initial endosperm development recognized are free nuclear 

 division and w T all formation, and these types have been regarded as charac- 

 teristic of different genera and even families. In V. corymbosum, from material 

 collected from a single plant, Stevens finds that endosperm development may 

 begin either way. This emphasizes the fact that many of our morphological 

 categories have been too rigidly defined. — J. M. C. 



North American flora. — "The second part of volume 24 chiefly consists 

 of the completion of the genus Parosela, by Rydberg, 43 species of which 

 had been published in the preceding part. 9 This genus is recognized to 

 include 178 North American species, 46 being described in the present contri- 

 bution as new, and many being species transferred from other genera. The 

 three other genera presented are Thombera (13 species, 5 new), Petalostemon 

 (42 species, 8 new), and Kuhnistera (2 species). — J. M. C. 



New species of Piper. — In connection with the biological survey of 

 Panama, conducted several years ago by the Smithsonian Institution, the 

 collected material of the Piperaceae was sent to the late Casimir DeCandolle, 

 whose determinations have just been published. 10 The collection was found to 

 include 27 new species of Piper and 4 new varieties. — J. M. C. 



7 Yampolsky, Cecil, The occurrence and inheritance 

 plants. Amer. Jour. Bot. 7:21-38. 1920. 



8 Stevens, N. E., The development of the endosperm ii 

 Torr. Bot. Club 46:465-468. figs. 4. 1919. 



9 Bot. Gaz. 68:65. I 9 I 9- 



^ w DeCandolle, Casimir, New species of Piper iroxr 

 Miscell. Coll. 71 : no. 6. nn t? m™ 



ymbosu 



Smithsonian 



