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BOTANICAL GAZETTE 



the stipes develop together as a common stipe, at the summit of which the 

 drupelets "are placed in a starlike manner." 



Standley, 18 in continuing his studies of tropical American plants, under a 

 variety of titles has described numerous new forms as follows: Wercklea and 

 Peltaea, new genera of Malvaceae; new species in Cyperaceae (2), Amaran- 

 thaceae (18; 11 of which belong to Iresine), Allionaceae (3), Caesalpiniaceae 

 (4), Mimosaceae (4), Fabaceae (6), Ebenaceae (5; 3 of which belong to Dio- 

 spyros), and Rubiaceae (20); also new species in Geranium (2), Malache (4), 

 Waltheria, Styrax, Evea (2), Duggena, Arctophyllum (3), and Psychotria (11).— 

 J. M. C. 



Inheritance of awns and velvet chaff. — Students of genetic problems in 



of biotypes possessing diverse factorial constitutions with respect to the char- 

 acters under consideration. The Howards have shown 1 " that the velvet chaff 

 of wheat may be of two distinct kinds, characterized by different types of hairs. 

 Each kind of hair is produced by a distinct Mendelian factor, and the two kinds 

 are mingled on the glumes when both of these factors are present. Only in 

 the absence of both velvet factors are the glumes glabrous. Selfing any hybrid 



15 velvet chaff to 1 glabrous. This result has received further confirmation 

 in a recent paper by the same authors, 20 which is devoted chiefly to the inherit- 

 ance of awns. Most of the genetical studies which have been made with the 

 latter characteristic have involved forms which are not completely awnless. 

 The Howards used, among others, completely awnless varieties, and demon- 

 strated that two independent factors affect the extent and nature of the awn- 

 ing. One of these factors (T) produces short awns or "tips" only, which arc 

 developed most conspicuously in the distal portion of the spike, while the other 

 (23) also produces short awns, which are distributed more uniformly over the 

 spike. The combined action of both of these factors in the homozygous state 

 is required to produce the fully bearded condition. With respect to both of 

 these factors, the heterozygote is successfully distinguished from the homozy- 

 gotes by a distinctly intermediate condition. Completely bearded wheats 

 have the formula TTBB, and the completely beardless are ttbb; the complete 

 ratio of forms produced in the F 2 of a cross between awned and awnless forms, 



Contrib. U.S. Nat. Herb. 18:87-142. 1916. 



'* Howard, A., and Howard, Gabrielle L. C, On the inheritance of some 



30 . On the inheritance of some characters in wheat. II. Mem. Dept. Agric. 



India 7:273-285. 1915. 



