r 



1920] HOLM—CICER ARIETINUM 



451 



Characteristic of the stem structure of Cicer, therefore, is the 

 presence of endodermis in the epicotyl, and its absence from 

 the internodes above; the glandular hairs, very seldom met with 

 in this family; the presence of interfascicular cambium; and the 



in 



LEAF 



The leaf structure is not exactly bifacial since the stomata are 

 distributed over both faces, and equally abundant; but the chloren- 

 chyma shows both palisade and pneumatic tissue. Hairs like 

 those of the stem abound on both faces of the blade, and the 

 cuticle is wrinkled above and below the stronger veins; otherwise 

 it is thin and smooth. The epidermis is slightly thick-walled 

 above and below the midrib, and the lateral walls are undulate 

 on the dorsal side (fig. 19), but almost straight on the ventral side. 

 The stomata (fig. 19) have no subsidiary cells; they are free, and 

 raised a little, with a wide shallow air chamber. The chlorenchyma 

 covers both faces of the leaf, and consists of a ventral palisade 

 tissue of three layers (fig. 13, JP), and of a pneumatic tissue of 

 about five strata (fig. 13, P + ). There is neither collenchyma nor 

 water storage tissue, and the veins are completely imbedded in 

 the chlorenchyma. Around the midrib and the strong secondary 

 veins are parenchyma sheaths, each cell of which contains a large 

 rhombic crystal of calcium oxalate. Moreover, the midrib has a 

 little pericyclic stereome on the leptome side, and consists of 

 a single collateral mestome strand, with leptome, cambium, and a 

 few vessels. 



Characteristic of the leaf structure, therefore, is the distribution 

 of the stomata over both faces of the blade; the dense chloren- 

 chyma; the poor development of mechanical tissues; and the 

 crystal bearing parenchyma-sheath. The internal structure of 

 C. arietinum thus resembles that of a xerophilous plant among the 

 Papilionaceae, especially when we acid the profuse development 

 of hairs, pointed, clavate, and glandular. The species evidently 

 originated in a country with a warm and dry climate, and it has 

 been suggested as possibly between Greece and the Caspian Sea. 



Clinton, Md. 



