150 



(BAILLON) ; and lastly to the Begoniaceae (BAILLON) in the unisexual flowers, 

 in the inferior ovary, in the connate stamens, in the leaf - venation, in the 

 placenta and in the exalbuininous seeds. Another instance of the transition, 

 from the Parietales to the Metachlarnydese can be seen in the ganaopetalous 

 genera of the Theacene, such as Eurya and Anneslea. Moreover, some connec- 

 tions may be found between the Parietales and the Ericales, when we compare 

 the StachyuracefB^ and Clethracefe (BAILLON). As is stated above, the relation 

 of the Parietales in one point or another to other series is of wide extent, 

 reaching from the Salicales or the Centrosperinpe far up to the Cucurbitales. 

 At one time we consider their gamopetalous character, and place them in the 

 Metachlamydeae. At another time their polypetalous genera make them 

 assignable to the Archichlarnyde?e. The systematic position of the series should, 

 therefore, be dynamic. As to the families in this series, it is absolutely 

 impossible to arrange them serially, as they inter-relate one another like the 

 methes of a net. To this fact, I shah 1 return later on. What ENGLEK mentions, 

 in this case, partly confirms the above statement. He says ?) : 



Eine solche Eeihe wie die Farietales 1st niclit ein einheitlicher 

 monopkyletischer Verwandtschaftskreis, sondern ein Complex von 

 mekreren Verwnndtschuftskreisen, die teilweise von verscliiedenen 

 Anfangspunkten ausgehend in ihrer Entwickelung auf derselben 

 morpliologischen Hauptstufe Halt gemacht haben, teilweise, wie die 

 TJnterreihe der Flacourtiineae noch verschiedene Hauptstufen der 

 Entwickelung erkennen lassen. 



But, when this series had been described by ENGLER as a complex of many 

 groups, how then is it possible to give it a fixed place? The answer should 

 decidedly be negative. 



Next, in ENG LEE'S system follow the Opuntiales 4) . As has already been 

 stated, they bear resemblance in a greater or less degree to other series ; to 

 the Ranales in the spiral arrangement of the floral elements, to the Parietales 

 in the structure of the ovary, and to the Centrospernige in the relative position 

 of the sepals, p9tals and stamens. Consequently, their natural position changes 

 from this place to that according to the way in which they are considered. 



1) Nac-lit. Pfl.-fam. IfT. 6, a. p. 133. 2) 1. c, ITL 6, p. 193. 



3) ENGLEK, A. Erlautemngen, 1. c. p. 368. 



4) ENGLEB, A. Erlauiterangen, 1. c. p. 3G9. 



