190 Trans. Acad. Sci. of St. Louis. 



PAPIIilONACEAE — Phaseoleae. 



Apios, Moench. 



Apios agrees with the other Phaseoleae in the poorly 

 developed endosperm, and the presence of starch grains in 

 the embryo. 



Apios tuberosa, Moench. 



PL XIX. f. 4. 



Testa 140-145 /a thick. 



Malpighian. Cells 52-56 /x long; light line close under 

 the cuticle ; cell-cavity large at the base, abruptly contracting 

 near the light line; the cells are colored brown. 



Osteosclerid. Cells are 15-18 ^ long, I-shaped, separated 

 by a small intercellular space. 



N'utrient. This layer is compressed, divided into two 

 parts. Cells of the upper part thin- walled and much larger 

 than the thick-walled cells in the lower part. 



Endosperm. Keduced to a single row, the aleurone layer. 



Embryo. The epidermal cells are smaller than the under- 

 lying parenchyma, which has small intercellular spaces. All 

 of the cells contain an abundance of small starch grains. 

 They are much smaller than in allied genera. Aleurone 

 grains are also abundant. 



MucuNA, Adans. 



The structure of the seed-coat is by no means uniform in 

 the different species of the genus. In Mucuna urens, studied 

 by the writer, the brown Malpighian cells are long, and 

 coriaceous. The cuticle is also well defined. The nutrient 

 layer is well developed and not compressed as in many other 

 genera of Leguminosae, The structure of the entire seed indi- 

 cates adaptation for dissemination by water. The Malpighian 

 cells of Mucuna pruriens are less coriaceous, and the cells of 

 the nutrient layer are more compressed. Endosperm reduced. 

 Cells of the cotyledons contain an abundance of large starch 

 grains. 



