DKSKKT sr.i.iM,i\(;s 155 



Palma loca. — A seedling 15 cm. from the base of the 

 stem was found growing in a clump of brush. 1 he shoot 

 at the base has a diameter of 8 mm. sending up five leav^es^ 

 the broadest of which has a breadth of 8mm. The lower- 

 most is probably the cotyledon. Fhe juvenile leaves bear 

 none of the filamentous marginal appendages, nor the strongly 

 spinose apex, nor the color markings of the mature ones. 

 1 he stem proper is of course very short, the leaves making 

 up the height of the plant. 



FVom the base of the stem arises the tap root, and, 

 arising laterally from the stem are two other roots. All 

 three of these are spindle-shaped, and, as a transverse sec- 

 tion shows, are composed of cortical tissue, with the exception 

 of the central cylinder, which, in a root having a diameter 

 of 8 mm., is 0.5 mm. thick. The cells of the cortex are 

 large and thin-walled, and secrete a mucilage. A dark red 

 bark clothes the tuber, arising from a superficial bark-form- 

 ing layer of cells derived secondarily from the most super- 

 ficial Cortical cells. The measurements of these organs are; 



Tap-root spindle, 2.6 cm. long by 0.5 cm. diam. 



The two others, 2.8 cm. long by 0.6 cm. diam. 



2.2 cm. long by 0.8 cm. diam. 



The lower end of each tuber is continued into a slender 

 root, and from it also spring laterally two or three secondary 

 roots, giving rise to still others of the third and fourth order. 



That these tuberous developments of the early roots of 

 this seedling are water-storage organs appears from the 

 structure, relative size, and contents. No starch is to be 

 found. Such distinctixe organs are absent from the old plant, 

 though, of course, the same function is taken up in other 

 ways. 



Ocotillo. — {Foitqineria spleudtnis.) — A specimen 6 cm. in 

 height, 3 mm. thick at the base, has a maximum diameter 

 of 6 mm. at its thickest point, which is near the top. The 

 plant'et is club-shaped, and is at least three years old, tlie 



