1915] 



BESSEY PHYLOGENETIC TAXONOMY 127 



Here we have a possible explanation of the marked herbaceous- 

 ness of monocotyledons as contrasted with the general ten- 

 dency toward a more ligneous structure in dicotyledons. 



Sub - Class OPPOSITIFOLIAE - STROBILOIDEAE. 



' 'Cone flowers." Axis of the flower normally cylindrical, 

 spherical, hemispherical or flattened, bearing on its surface 

 the hypogynous perianth, stamens and pistils (or the stamens 

 may be attached to the corolla). 



Super - Order Strobiloideae-Apopetalae-Polycaepellatae. 

 Carpels typically many, separate or united; petals separate. 

 Flowers mostly actinomorphic. This super-order has much in 

 common with the Alismatales, and also with the Cotyloideae- 

 Apopetalae. In fact, these three groups appear to have 

 diverged from a common point of origin. 



Order Eanales. All parts of the flower mostly spirally 

 arranged (acyclic), free (not united) ; carpels typically many, 

 separate (or rarely united), rarely reduced to 1; stamens gen- 

 erally indefinite ; embryo mostly small, in copious endosperm. 



(Species about 5551.) 



The twenty-four families here included in the order Randies 

 naturally group themselves about three centers, the magnolias 

 (Magnoliaceae), the anonas (Anonaceae), and the buttercups 

 (Ranunculaceae) . The plants in these centers are typically 

 diplochlamydeous, polycarpellate, hermaphrodite, and actino- 

 morphic, and the modifications in the surrounding families 

 have been such as to result in an achlamydeous structure, 

 which may be monocarpellate, diclinous, and even zygomorphic. 

 Ranalean evolution has thus been one of more and more 

 marked simplification of flower structure. 



It is interesting to observe that while the families of Ranales 

 have thus been evolved, the order has given rise to no less 

 than five phyletic groups of full ordinal rank. One of these 

 (Malvales) has produced a further modification (Sarraceni- 

 ales), for three of them the evolutionary development came 

 to a stand-still with the ordinal limits (Geraniales, Guttiferales 

 and Rhoedales), while the virile Caryophyllales continued a 

 development beyond its ordinal limits into the Ebenales, Eri- 



