70 



BOTANY. 



or a column, sometimes in a mass. Its most common forms 

 are met with in 



(1) The Hairs of many plants. (See page 42.) 



The other trichome forms are : 



(3) Bristles, each consisting of a single pointed cell or 



Fig. 43. 



Fig. 44. 



Fig. 43.— Diagrams of dichotomous branching. A, normal dichotomy, 

 in which each branch is again dichotomously branched ; B, helicoid dichot- 

 omy, in which the right-hand branch, i-, does not develop further, while 

 the left-hand one, Z, is in every case again branched ; C, scorpioid dichot- 

 omy, in which the branches are alternately further developed. 



Fig. 44.— Diagram of botryose monopodial branching. The numerals 

 Indicate the " generations." 



a row of cells, whose walls are much thickened and hard- 

 ended. 



(3) Prickles, like the last, but stouter, and usually com- 

 posed of a mass of cells below. 



(4) Scales, in which the terminal cell gives rise by fission 

 to a flat scale, which soon becomes dry. 



