^66 PHANEROGAMS. 



the number and position of which the number and position of the carpels might 

 otherwise be more easily determined, we are thrown back on the direct observation 

 of the first stages of development and on the numbers of the styles and stigmas. 

 Failing this, the solution of the question depends on morphological relationships 

 which are still by no means made out with sufficient certainty, notwithstanding the 

 numerous researches which have been made on the development of the flower. 



Besides the number of the carpels which have coalesced to form the ovary, it 

 is a question of interest whether in any particular case the ovules have been pro- 

 duced laterally on the floral axis or as its terminal structure. In the cases of 

 Piperacese, Polygonacese, Naias, Typha, &c., where only a single ovule springs from 

 the base of the ovary, it is evident that this must be the terminal structure of 

 the floral axis ; and the investigations of Hanstein and Schmitz, Magnus, Rohrbach, 

 and Payer, have proved in addition that not only the ovule as a whole, but the 

 nucellus itself, must be considered as a terminal structured It must not, however, 

 be inferred from this that every ovule which springs- from the base of the cavity of 

 the ovary necessarily forms the apex of the floral axis ; for it is conceivable that the 

 axis itself may have ceased to grow, but has produced an ovule at the side of its 

 apex, a case which we shall meet with further on in the inferior ovary of Compositse. 

 In a few cases the floral axis rises free within the spacious cavity of the ovary and 

 produces ovules laterally, as occurs in Primulaceae (Fig. 392) and Amaranthaceae 

 (in Celosi'a, according to Payer). 



The Inferior Ovary of epigynous flowers results from the retardation or com- 

 plete suppression of the apical growth of the young floral axis, its peripheral tissue 

 rising as an annular zone, and producing on its free margin the perianth, stamens, 

 and carpels (Figs. 393, 394). The hollow structure which is thus formed, and 

 which is at first open above, is afterwards covered over by the carpellary walls 

 which close in above it ; the apex of the floral axis lies at the bottom of the elongated 

 cup-shaped or tubular cavity. Notwithstanding this striking displacement of the 

 axial parts, the structure of the inferior ovary resembles that of the free polycarpellary 

 ovary in almost all respects ; it may also be either unilocular or multilocular — if 

 unilocular, the placentation may be basilar, lateral, or parietal. When the placentation 

 is basilar, the ovule sometimes appears as if it were the terminal structure of the 

 apex of the axis ; as for instance the erect ovule of Juglandeas. In Compositae, 

 on the other hand, the position of the single anatropous ovule is not terminal 

 but lateral; the apex of the floral axis may often be clearly made out as a small 

 elevation beside the funiculus, and in abnormal cases it undergoes further develop- 

 ment into a leaf-bearing shoot ^. In Samolus the apex of the axis rises within the 

 unilocular inferior ovary as in the superior ovary of other Primulaceae (Fig. 392), and 

 bears a number of lateral ovules. If the placentae of the unilocular inferior ovary 

 are parietal, they form on the wall two, three, four, five or more ridges from above 

 downwards or from below upwards, and bear two or a larger number of rows of 

 ovules (as in Opmifia or Orchideas). These placentae, which project more or less 



^ [See infra, p. 574.] 



^ Cramer, Bildungsabweichurigen und morphologische Bedeutung des Pflanzen-Eies (Zurich 1864). 

 — Kohne, Die Bllithenentwickelung der Compositen, Berlin 1869, — Buchenau, Bot. Zeit. 1832, 

 No. 18 et seq. 



