FOLIAGE LEAVES. 409 



posure to light is gained with little shading. The dragon tree 

 screw-pine, and plants grown in greenhouses also illustrate this 



Fig. 447- 

 Screw pine (Pandanus) showing prop roots and radiate pattern of leaves. 



type. It is also shown in cycads, palms, and many ferns, although 

 these have divided leaves. 



782. Compass plants. These plants with vertical leaf arrange- 

 ment, and exposure of both surfaces to the lateral rays of light 

 have been mentioned in other sections (Lactuca scariola). 



783. Open patterns. Open patterns are presented by divided 

 or "branched" leaves. Where the leaves are very finely dis- 

 sected, they may be clustered in great profusion and yet admit 

 sufficient light for some depth below. Where the leaflets are 

 broader, the leaves are likely to be fewer in number and so 

 arranged as to admit light to a great depth so that successive 

 leaves below on the same or adjacent stems may not be too much 

 shaded. On such plants, often the leaves lying next the ground 

 are entire or less divided. 



