Pammel — Caryopsis and Endosperm of some Grasses. 209 



of thinner-walled cells; the aleurone layer, of two to three 

 rows of nearly isocliametric cells, followed by the starch cells. 

 The starch cells are densely packed with polygonal grains, 

 apparently simple. Harz has described and figured the struc- 

 ture of Gynodon Dactylon^ with compound starch grains. The 

 same writer places Nardus siricta in this tribe, but Bentham 

 and Hooker exclude it. The Nardus has compound starch 

 grains like Gynodon (PI. XIX. 5). 



FESTUCEAE. 



The tribe Festuceae includes quite a large number of our 

 prominent forage plants. The microscopic structure of mem- 

 bers of this tribe has been studied by Harz. He describes 

 the following genera : Phragmiies^'^ Arundo,^ Melica,^ Dac- 

 tylis,* Poa,^ Glyceria,^ Festuca,'' Bromiis,^ Brachy podium,^ 

 /ScoloGhloa,^° and Koeleria.^^ 



Phragmites communis, Trin. Has a thin pericarp of three 

 to six rows of pigment cells. The testa consists of loosely ar- 

 ranged parenchyma cells. Remnants of the nucellus sparing 

 and much compressed. The aleurone layer of a single row of 

 cells, quadratic or tangentially elongated. Its contents, as 

 well as those of the embryo, are colored red with potash, ac- 

 cording to Harz. Small simple and compound starch grains 

 present (PI. XIX. 8). 



Koeleria sp. The epidermal cells of Koeleria are elon- 

 gated, the lateral walls with irregular outlines. The under- 

 lying portions of the pericarp consist of thiu-walled cells. 

 The testa is made up of one to two rows of nearly colorless, 

 tangentially elongated cells. Remnants of the nucellus pre- 

 sent but very much compressed or in some parts of the seed 

 more evident. The outer membrane of the aleurone layer 

 thick walled, inner part thinner. The layer consists of a 

 single row of cells. The starch cells contain compound grains, 

 the component parts are polygonal. In addition to the com- 



1 1. c. 1338. « 1. c. 1284. » 1. c. 1232. 



2 1. c. 1339. 6 1. c. 1300./. 178, II, III. i» 1. c. 1337. 

 ' 1. c. 1333. ' 1. c. 1290. /. 1 78, I. " 1. c. 1336. 

 ^ 1. c. 1299. 8 1. c. 1223. 



