Tun PLANT-BODY. 63 



(7) Tendrils and (8) Spines, which are reduced or de- 

 graded forms, composed of the modified fibro-vascular bun- 

 dles and a very little soft tissue; in the first the structures 

 are -weak and pliable, in the latter stout and rigid. 



The altogether special modifications of the phyllome, as 

 in pitchers and cups, will be noticed hereafter. 



121. Trichome. — The triohome is a surface appendage 

 consisting of one or more cells usually arranged in a row 

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

 are met with in 



(1) The Hairs of many plants. (See page 36.) 

 The other trichome forms are: 



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

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

 ened. 



(3) IVickles, 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. 



(5) Glands, which are generally short, bearing one or 

 more secreting cells. 



(6) Hoot-hairs, which are long, thin, single-celled (in 

 mosses a row of cells), and subterranean. 



(7) Sporangia of ferns and their relatives, some of whose 

 interior cells develop into reproductive cells (spores). 



(8) Ovules of flowering plants one or more of whose cells 

 develop into reproductive cells (embryo-sacs). 



122. Root. — The root is that portion of the plant-body 

 which is clothed at its growing point with a root-cap. In 

 ascending through the vegetable kingdom roots are the 

 latest of the generalized forms to make their appearance, 

 and in the embryo they appear to be formed later than 



