SIMPLIFIED LEAVES 21 



PROPHYLLS OR PROPHYLLA. 



In many Dicotyledons the first two, therefore the lowest two, 

 leaves borne on each branch are small and scale-like, These 

 two simple leaves— the prophylls — are inserted on opposite 

 faces, the right and left sides of the branch. In Mono- 

 cotyledons, on the other hand, there is only one of these 

 simple leaves at the base of the branch, and it is inserted 

 alone on the upper face of the branch — that is, on the face 

 which is directed towards the main axis. We can easily re- 

 member these facts if we recollect that in Dicotyledons and 

 Monocotyledons the leaves first formed on any stem are 

 usually simplified. The first leaves of the primary stem are 

 cotyledons ; those of a lateral stem are prophylls. In Dicoty- 

 ledons the primary axis has two cotyledons, the branch two 

 prophylls; in Monocotyledons the primary axis possesses one 

 cotyledon, the branch one prophyll. 



BRACTS. 

 Often the leaves situated on that region of the stem which 

 bears the flowers are simpler, and usually smaller, than the 

 foliage - leaves of the same plant. These simplified leaves 

 borne in the region of the flowering part of the shoot are 

 termed bracts — e.g.^ Daisy, Bluebell, Hyacinth. In the 

 majority of cases, bracts are small, without stalks, and attached 

 by broad bases ; their margins tend to be entire. Bracts 

 may assume the form of small scales, as, for example, in the 

 case of the glumes of grasses (fig. 231), the chaffy bracts of 

 the Sunflower (fig. 208). Exceptionally large sheathing bracts, 

 which enclose the whole inflorescence, occur in the Arum, 

 also in the Snowdrop, and are termed Spathes (fig. 226). 



CONSIDERATIONS WITH REGARD TO SCALES, 

 PROPHYLLS, COTYLEDONS, AND BRACTS. 



The remarks in the few preceding paragraphs render it 

 obvious that scales are defined by their form, and are not 

 confined to any particular regions of the shoot ; but the other 

 three varieties of simplified leaves occupy certain definite 

 positions on the plant, and are defined as well by their position 

 as by their simple forms. That they all represent true leaveS 

 is proved by the following considerations: — (i.) They are 

 lateral appendages of the stem arranged like foliage-leaves. 



