64 BOTANY. 
caulome and phyllome. They present fewer variations 
than any of the other generalized forms. The ordinary 
(1) Subterranean roots of plants are typical. They differ 
Fia. 38, Fie. 39. 
Fic. 38.—Diagrams of dichotomous branching. 4, normal dichotomy, in 
which each branch is again dichotomously branched; B, helicoid dichotomy, in 
which the right-hand brarich, 7, does not develop further, while the left-hand 
one, l, is in every case again branched; C, scorpioid dichotomy, in which the 
branches are alternately further developed. 
Fria. 39.—Diagram of botryose monopodial branching. The numerals indicate 
the “ generations.” 
but little from one another in whatever plants they may 
be found. 
The other root-forms are: 
(2) Aerial roots, which project into the air, and often 
have their epidermis peculiarly thickened,'as in the epi- 
phytic orchids. 
(3) Roots of Parasites, which are usually quite short, 
