158 Chapters in Modern Botany CHAP. 



five leaflets and the usual reduced bud-scale. Finally, bud- 

 scales may be derived, as in the beech, from those little 

 appendages of leaves which we call stipules. When spring 

 comes, and the bud passes from a latent to an active period, 

 the protective scales often almost dead are thrown off. 

 and often carpet and tint the ground like a foreshadowing 

 of autumn. The autumn indeed it is for these sacrificed 

 leaves which are to know no summer. 



Arrangement of the Leaves in the Bud (Phyllotaxis) . 

 It is interesting to dissect a few buds to see the various 

 ways in which the young leaves are packed together, a 

 great number being compressed into the small space. This 

 neat packing has the further importance that it mainly 

 determines the position of the leaves on the future stem or 

 branch. We have all observed the regular arrangement of 

 scales in a fir-cone or of leaves in a crowded rosette like 

 that of a house-leek, stiff and orderly as in a prize double 

 camellia, but so it is really in the longest stem. Mark the 

 knots upon a thorn walking-stick ; see the house-leek send 

 up its long scanty-leaved flower-stalk ; imagine the fir-cone 

 pulled out ; or reverse the experiment, and let a stretched 

 elastic cord stand for a stem ; wind round this, in ascend- 

 ings spirals at regular distances, a string bearing knots to 

 represent leaf insertions, or still better, holding paper leaves 

 or real ones, also of course at regular distances. Then 

 allow the elastic cord to contract ; the leaves will bend to 

 assume positions such as occurs in nature within a bud. 

 Twist the cord, and the leaf-spiral becomes more crowded 

 and complex, the leaves therefore more perfectly packed 

 one upon another ; so we may reproduce the spirals of 

 different plants. Here then, especially if of any mathe- 

 matical tastes, we have an interesting field of inquiry 

 What are the different spirals to be met with in plants? 

 how far are these constant or related? what effect will an 



