200 Trans. Acad. Sci. of St. Louis. 



The most important contribution from a systematic stand- 

 point was made by Harz, 1 who studied representatives of not 

 only the economic grasses but many species of the indigenous 

 European grasses. 



The structure of the caryopsis is quite simple in all of the 

 grasses. The pericarp consists of a usually thickened 

 epidermal layer followed by thick-walled sclerotic 

 parenchyma with pore canals. The poorly developed vas- 

 cular elements occur within the parenchyma. In Zea, 

 Coix, and Secede the pericarp is considerably developed. 

 In Cenchrus, Sporobolus, and Elymus the pericarp is but 

 slightly developed. In all of these except Sporobolus the 

 protective features are preserved in the pericarp. The testa 

 is more delicate and consists of several rows of thin-walled 

 cells, longer than broad. The nucellus is not evident in 

 most genera except in the groove, where it persists. True 2 

 has called attention to its occurrence in Zea, and Harz 3 in 

 Bromus, Fesluca, and Br achy podium. Tschirch & Oesterle 

 also figure and describe it in several genera. It occurs in An- 

 dropogon, Triticum, Hordeum and Secale, though not well 

 developed. In our species of Elymus, Festuca, and Bromus 

 it is well developed and consists in part of a gelatinous layer. 

 The endosperm is always well developed. The aleurone layer 

 varies, consisting of a single row of cells in Zea, Triticum, 

 Cenchrus, and Elymus; more than one row of cells in Arrhena- 

 therum avenaceum, Hordeum, Boideloua and some species of 

 Fesluca. These cells never contain starch but an abundance 

 of a diastatic ferment. The cells following the aleurone are 

 thinner-walled and contain some albuminoids, the amount 

 varying in different species, a small quantity of fat and an 

 abundance of starch. The starch occurs as simple or com- 

 pound grains, simple in Zea where they are solidly packed. 

 This is also true of Panicum Crus-galli, Boideloua hirsula, 

 and Setaria. More loosely arranged in Hordeum, Triticum, 

 Secale and Andropogon. The simple starch grains are fre- 

 quently angular in Zea and Panicum; round or somewhat 

 lens-shaped in Hordeum, Andropogon, and Triticum. Some 



1 Landwirthschaftliche Samenkunde. 2 1. c. 



' Linnea 43: 1-30. — Samenkunde 2: 1223. 



