66 GRASSES OF IOWA. 



hairy. The large epidermal cells are thick-walled, slightly 

 irregular on the surface, followed by several rows of thick- 

 walled cells in a general way much like the epidermal cells. 

 The testa consists of a much compressed layer mostly of two 

 rows of thick- walled cells; remnants of the nucellus evident. 

 The aleurone layer of the endosperm consists of one or two 

 rows of cells; the outer portion of the starch cells contains less 

 starch than the inner. The starch consists of large com- 

 pound grains, the component parts five to six-sided. 



Secale cereale L. An excellent account of the structure of 

 this fruit will be found in the works of Harz, Tschirch & 

 Oesterle. Tietschert, Gregory and other writers on economic 

 food products. Literature of the whole subject is given fully 

 in a paper by Pammel.* 



The pericarp consists of tingentially elongated epidermal 

 cells with large cavities. The outer wall is thickened as 

 well as the inner, the lateral walls thinner. Harz states that 

 there is an important distinction between Secale and Triticum: 

 a somewhat analogous structure, however, occurs in the spelts 

 The epidermal layer is followed by smaller thin- walled 

 parenchyma cells. The layer next to these parenchyma 

 cells is frequently composed of thick-walled porous cells with 

 pore canals. These cells not evident except in mature fruits. 

 The testa is but slightly developed and consists cf compara- 

 tively small cells frequently colored brown. The nucellus 

 occurs as a remnant especially in the groove, where the cells 

 are thick-walled and somewhat gelatinous. The endosperm 

 resembles that of wheat. The aleurone layer consists of a 

 single layer of cells. The exterior walls are greatly thick- 

 ened. The cells of the starch layer large, containing a large 

 number of round or elliptical starch grains, extremely vari- 

 able in size. The starch grains on the whole are larger than 

 those of the genus Triticum. 



The adhering palet cons'sts of several rows of thick- walled 

 cells. The epidermal cells are longer and somewhat thicker- 

 walled. The cells below are also thick-walled, provided with 

 pore canals. In places the epidermal cells develop into a 

 short trichome. Underneath the thick-walled cells occur sev- 

 eral rows of thin- walled irregular parenchyma cells. The 



* Pammel. Histology of the Caryopsls and Endosperm of some grasses. Trans. 

 Acad. Scl. of St Louis. 8: 199. pi. 17— 19. Proc. la. Acad Sol., 5: 199, 1897. Oontr. 

 Bot. Dept. la. St. Coll. Agr. and Mech. Arts, 10. 1, 1898. Hays and Boss, Minn. Agr. 

 Exp. Sta. Bull. 62: 418. BoUey, Bull. N. D. Agr. Exp. Sta. 9: 1. 



