416 MORPHOLOGY OF THE ANGIOSPERMS 



carpellary gynoecia of the Ranunculaceae and Rosaceae and the uni- 

 carpellary flowers of Berheris vulgaris. 



The presence of three carpels in the Berberidaceae is to be expected, 

 because of the trimerous pattern of the flowers and because the related 

 Lardizabalaceae have three carpels. The three carpels in Berheris are 

 shown, by anatomical study, to stand at different levels, with the upper 

 two commonly reduced, the uppermost strongly so. The two-carpellary 

 gynoecia of most genera in the family represent a reduction from three. 

 The different levels of attachment of the three carpels in Berheris in- 

 dicate spiral arrangement, evidence of ranalian relationships, though 

 a high type of syncarpy is present. (Syncarpy in gynoecia with few 

 spirally placed carpels is probably rare.) 



The genera Berheris and Mahonia stand apart from the other genera 

 in their woody habit. In their stem anatomy, they show evidence of 

 derivation from herbaceous ancestors. The woody stem consists of a 

 compacted cylinder of vascular strands, separated by broad rays, like 

 those of many herbs. In histological characters, the xylem resembles 

 that of herbs with well-developed woody cylinders: vessel elements, 

 with few exceptions, short and simply porous; parenchyma absent; 

 fibers libriform, short, sometimes septate; intervascular pitting alternate. 



Although highly specialized in habit and in gynoecial stiaicture, the 

 ovules {Berheris) show some primitive characters — a massive nucellus 

 and multiple archesporial cells. The embryo resembles that of the 

 Ranunculaceae. 



The family is apparently closely related to the Ranunculaceae. It is 

 heterogeneous, with subfamilies probably derived independently from 

 herbaceous stock of primitive ranalian type. 



Nymphaeaceae and Cabombaceae 



The Nymphaeaceae, together with the probably related Cabombaceae, 

 form a complex taxon, remarkable for retention in the flowers of primi- 

 tive characters combined with specialized structure. Morphologically, 

 they are especially important, because they provide examples of primi- 

 tive structure in herbaceous ranalian taxa similar to those of the woody 

 taxa — in perianth, stamens, and placentation especially. In the perianth 

 (calyx and corolla distinct) and in the androecium and gynoecium, 

 there is advance from numerous, spiral, to few, cyclic organs. The 

 stamens range from laminar forms to those with well-differentiated anther 

 and filament. Laminar placentation is characteristic of the Nymphaea- 

 ceae, but there is reduction to the puzzling types of Cahomha, Brasenia, 

 and Nehimbo (Fig. 85). The Cabombaceae, as compared with the Nym- 

 phaeaceae, are advanced and provide, in some characters, examples of 

 late stages in specialization. 



