574 SECONDARY CHANGES. 



1. Stem cylindrical or hardly four-cornered, bast-plates remaining a long 



time of the same breadth, then with high irregular steps : Petajtoma 

 Miers. 



2. Stem cylindrical, with fine longitudinal furrows, subsequently thrown off. 



Steps of the bast-plates appearing late, broad, and few in number : 

 Stizophyllum Miers. 



3. Stem cylindrical with four narrow furrows. Bast-plates broad. Steps 



present from an early age, as broad or broader than high : Cuspi- 

 daria DC. 



4. Stem, at least when old, four-cornered ; cortex uneven, u ith many 



lenticels. Bast-plates with regular steps, and one broad medullary 

 ray between each two step-like bands : Tynanthus INIiers. 

 /3. Steps not broader than the space between two medullary rays of the 



wood. Stem cylindrical. Bast-plates with a very broad middle lamella : 



Fridericia Mart. 



{b) Stony sclerenchyma in the cortex. 



1. Stem somewhat flattened opposite the bast-plates. Bast-plates short, 



somewhat widened. Steps not broader than the space between two 

 medullary rays of the wood. Stony elements only distributed in the 

 outer cortex, and in small quantity in the primary bast : Tanxcium Sw. 



2. Stem cylindrical. Steps of the bast-plates few. A continuous ring of 



stony elements 6-7 layers thick beneath the surface : Adenocalymma 



Mart, 

 b. Stem when young with four projecting ridges, these are later thrown off, and 

 replaced by channels (comp. Fig. 225). Steps of the bast-plates broad, 

 irregular: Phonotoma Miers. 



C. Bast-plates partially constricted and destroyed by pressure through tangential 

 widening of the zones of wood. Young branches octagonal. Angles thrown 

 off later. The old stem cylindrical. Cortex thick : Pithecoctenium Mart. 



II. Bast-zones successively 4, 8, 16, 32. 

 A. Wood always without displacement or separation of the older zones through 

 subsequent intercalary formations. 

 a. Without subsequent formation of wood in the cortex. 



{a) Young shoots cylindrical, without ridges which may be thrown off. 

 a. Stony elements in the outer cortex, and very numerous in the outer region 



of bast. Bast-plates with very irregular steps : Phryganocydia Mart. 

 ^. Without stony elements in the cortex. 



t The four first bast-plates long and narrow, the rest short and broad. 



Cortex with red colouring matter : Cydista Miers. 

 tt All bast-plates of similar form. Cortex without the red colouring. 



1. Stem twisted like a rope, with eight external rounded projections. Bast- 



plates of successive age differing little in length, all very narrow^ and 

 with few steps ; the four first with broad closely arranged medullary 

 rays externally. Cortex without sieve-tubes ^ : Pyrostegia Pr. 



2. Stem not rope-like. Wood very dense, with very narrow fibres and 



vessels. Bast-plates very numerous, steps high, broad, irregular, 

 medullary rays between the middle and the lateral lamellae of a plate 

 hardly any broader than the rest. Pith very narrow : Clytostoma Miers. 



3. Stem not rope-like, or only slightly so. Texture of the wood loose and 



porous. Steps of the bast-plates very few. Medullary rays between 



* 'Pas de cellules grillagees clans I'ecorce' (? Author). 



