1917] MARKLE—ROOT SYSTEMS 181 
many are necessarily incomplete. It was found possible to photo- 
graph some of the larger perennials zm situ, but in general it was 
found much more satisfactory to make accurate diagrams of the 
horizontal and vertical extensions of the root systems on paper 
metrically ruled in squares. The diagrams appear here drawn toa 
scale of 1:20, except figs. 25 and 26. While in general only the 
roots lying in or near a particular plane are represented, it was 
generally found possible without much distortion to include the 
most important part of each root system in both the horizontal 
and vertical diagrams. Roots that for some reason were not 
followed to the end are terminated in the diagrams by a broken 
line. Roots turning to a direction at right — to the ne of 
the diagram end in a dot. 
CANNON divides root cians into 3 types: (1) a generalized 
type, in which there is a well balanced development of both tap 
and lateral roots; (2) a specialized form, in which the tap root is 
-™Much the more prominent; and (3) a second specialized form, 
characterized by a relatively better development of the lateral 
roots. ee ; 5 
insta That age dents 
. Becetelle Wislizeni-—This lant a ee eS oe 
: om the mets and to the actoyes. = consists of 
relatively short tap root, with many strongly developed laterals 
horizontally rather near the surface of the ‘soil. Some ae 
of hens usually exceed the tap root in length. The specimen — 
en 
“oes I fe dt in ene gener ae an cI in . 
