VERTICELLATAE 435 



the dillenialian families have centrifugal stamens, but the value of this 

 character in determining relationships of major taxa has been, perhaps, 

 overemphasized. 



The Paeoniaceae, like the Nymphaeaceae, are an example of herbs 

 with some highly primitive characters. The peonies show a series from 

 woody shrubs to typical perennial herbs. Within the genus Faeonia, 

 the section Moutan (woody shrubs) has ten to fifteen carpels, and 

 primitive vessels and fibers; the herbaceous species have two to four 

 carpels (with additional, abortive carpels in some species) and ad- 

 vanced vessel and fiber t)'pes. The section Moutan is of special interest 

 as representing ancestral peony stock surviving in the mountains of 

 China, "a region noted for its wealth of relic types." 



Crossosomataceae 



The Crossosomataceae, though more specialized in wood structure 

 than the Paeoniaceae and Dilleniaceae, resemble these families, espe- 

 cially the peonies, in many characters and, doubtless, are well placed 

 as an advanced family in the Dilleniales. 



PIPERALES 



Chloranthaceae 



The number of known vesselless angiosperm taxa was increased in 

 1950 by the addition of the genus Sarcandra in the Chloranthaceae. The 

 Chloranthaceae are a small tropical and subtropical family, not well 

 known morphologically. Vesselless wood in this family — in contrast with 

 that in the Trochodendraceae, Tetracentraceae, and Amborellaceae — 

 accompanies flowers of advanced structure. The flowers, however, show 

 primitive anatomy — stamens with two traces and carpels with double, 

 partially fused, dorsal bundles. The vesselless wood and the primitive 

 vascular structure of the floral organs of Sarcandra (Figs. 23 and 82) 

 hardly form a suSicient basis for family rank for this genus. 



VERTICILLATAE ( Casuarinales ) 



Casuarinaceae 



The Casuarinaceae have been prominent in most of the older, as 

 well as the modern, classifications as the basic family of the dicotyledons 

 — a member of the Apetalae, Verticillatae, or Amentiferae. In the twen- 

 tieth century, they have been considered both highly specialized and so 

 primitive as to be excluded from angiosperms. A combination of very 

 simple, unisexual flowers and strange, coniferlike inflorescences, with 

 highly specialized vegetative habit — whorled scalelike leaves and decid- 



