12 DIMOEPHIC BRANCHES IN TBOPICAL CROP PLANTS. 



other ill definitely alternating sequences. The seeds of the cotton, 

 cofl'ee, and many other species do not grow at first into plants simi- 

 lar to the branches which produced the seeds. The seedlings at first 

 develop upright sterile stems and a series of vegetative branches. 

 Another type of branches is formed for the production of flowers and 

 fruit, and then there may be no return to the condition of the upright 

 main stem and the purely vegetative limbs except by way of the seed 

 and seedlings. 



In some plants the formation of different kinds of vegetative inter- 

 nodes is more specialized in relation to time, the whole plant going 

 over from one habit of growth or form of foliage to another. In the 

 eucalyptus and in many coniferous trees related to the juniper there 

 is a juvenile form of foliage altogether different from that of the 

 adult trees. This phenomenon is not to be confused with the simpler 

 dimorphism of branches shown in the tropical crop plants, though 

 some of the Coniferaj have this as well as the other. Cuttings of 

 lateral branches, not being able to replace the main axis, do not re- 

 produce the form of the parent tree. Some of the Conifera? pro- 

 duce a juvenile type of foliage only in exceptional cases of bud re- 

 version, which may even be confined to buds forced from the axils 

 of the cotyledons, as explained by Beissner and Beyerinck." 



DIFFERENT TYPES OF DIMORPHIC BRANCHES. 



It is easier to describe and compare the dimorphic forms of 

 branches in the several species of cultivated plants if we consider in 

 advance a general difference of function. Some branches have the 

 same form and functions as the axis or main stem of the plant, while 

 others are more or less restricted to the bearing of fruit or to other 

 special j^urposes. The specializations of the branches show various 

 directions and degrees in different species and varieties of plants, but 

 in each case it is possible to distinguish between branches that are 

 more similar to the main trunk and those that are less similar. 



In the present report the word " limb " is used as the general name 

 for branches that are unspecialized or that are specialized for vege- 

 tative functions instead of for fruiting. The limbs continue the 

 growth and share the functions of the trunk or main stem of the 

 plant.^ Limbs may have vegetative functions only and may be 



'^ Beissner. L. Ueber Jupcemlformen von Pflanzen, speciell von Conlferen, Bericht 

 liber die Verhandlungen der deutschen botanischen Gesellschaft. vol. 6, 1SS8, 

 p. Ixxxiii. Beyerincli, M. W. Beissner's Untersucliungen iieber der Ketinis- 

 porafrage, Botanische Zeitung, vol. 48, 1890, p. 518. 



''In the diagrams tliat illustrate^ the habits of branching in this rejiort the 

 vegetative limbs are drawn in solid lines like the main stem, while the fruiting 

 brandies are indicated by broken lines. (See figs. 1-7.) 

 198 



