OF SOME AMAZON TUBES. 9 



in appearance : there are, for instance, several Apocyneous trees 

 in which the inflorescence seems terminal, but has always above it 

 an apical leafy bud, conspicuous enough in some Plumierce, often 

 very obscure in certain Taberncemontance, but not the less actually 

 existing, and in consequence of whose presence the thick closely 

 scarred ramuli go on lengthening from year to year. In the dicho- 

 tomous ramification above-described, if the pairs of branches con- 

 tain an acute angle, the crown of the tree may be regularly 

 obconical and flat-topped ; but if the angle be divergent, the crown 

 will probably be more or less convex, and may even be reniform. 



In trees with alternate leaves and terminal inflorescence a dicho- 

 tomous ramification may equally exist ; but, as in this case one of 

 the two branches originates lower on the stem than the other, one 

 axis in each of the resulting pairs of axes will be stouter than the 

 other. To take an instance in the genus Ricinus, of which one 

 species multiplies abundantly in waste ground near Tarapoto, and 

 is known to the inhabitants of Maynas by the name of " Higuerilla 

 colorada " (its seeds affording the oil Avith which they feed their 

 lamps), young plants of this Ricinus have simple stems, which, in 

 three months after the germination of the seed, attain a height of 

 6-8 feet, and flower at the apex. Prom the axils of each of the 

 two uppermost leaves (very nearly contiguous, though still visibly 

 alternate) springs a branch in which the growth of the plant is 

 continued, the growth of the main axis ceasing with the flowers 

 which terminate it. The branches in their turn produce flowers 

 and branchlets at the apex, as the stem did ; and thus a dichotomous 

 ramification is generated and continued through many subdivi- 

 sions, till the plant becomes a stout little tree 25 feet high, with a 

 flat or subconvex top. 



An example of dichotomous ramification and almost flat top is 

 afforded by Panax Morototoni, Aubl. (" Morototo " of the Brazil- 

 ians), a tree abounding all along the Amazon, and even among 

 the roots of the Andes, whose white trunk and digitate leaves 

 give it the aspect of a Cecropia. The nearly allied genus Hedera 

 has frequently an isochotomous ramification ; II. resinosa, PI. Am., 

 has in some plants a trichotomous, in others a 5-chotomous ramifica- 

 tion ; II. maynensis, PI. Am. (Tarapoto), has the branches 4-nate. 



In general, any isochotomous ramification may be considered to 

 produce an obconical or corymbose outline in the plant*. Instances 



* Though I apply the term " isochotomous " to fasciculate branching, where 

 the branches spring several together from the same point and always at the 

 same angle, it should be understood that the ultimate branches are often fewer 



