ANGTOSPERMS. <nr 



be mentioned that there are cases in which the present state of our knowledge 

 does not enable us to decide with certainty whether the ovules arise from the axis 

 or from the margins of the carpels which have become united to it ; and these 

 doubtful cases are possibly more numerous than is generally thought. Payer's ob- 

 servations on Cerastium and Malachium show that in Caryophyllese the expanded 

 apex of the floral axis becomes considerably elevated even before the formation of 

 the carpels ; the carpels are then seen in a whorl, and attached by means of their 

 coherent margins to the elevated axis ; each forms what may be described as a pocket 

 attached to the axis. As the axis becomes elongated, the margins of the carpels 

 form radial dissepiments separating the pockets, which widen into loculi ; and the 

 carpels finally rise above the apex of the axis. In Cerastium and other genera the 

 dissepiments also rise above it as free lamella which do not meet in the centre, 

 so that the ovary is quinquelocular below, while in the upper part it remains 

 unilocular. The ovules are produced in two parallel rows on the axial face of 

 each loculus, this face being apparently formed from the axis itself. In some genera 

 of Caryophylleae it seems probable that the placentae are axile, while in others 

 they would appear rather to be carpellary. 



Among Superior Ovaries with axile Placentation, those of Typha, Naias, and 

 Piperacese^ require especial mention. In these cases the very simple female flower 

 consists (with the exception of the perianth of Typha, which is replaced by hairs) of 

 nothing but a small lateral shoot transformed into an ovary with a central ovule. 

 The apex of the axis of this shoot itself develops into the terminal nucleus of the 

 ovule, round which an annular zone grows up from below, overarches it, closes up 

 above, and thus forms the wall of the ovary. In Typha only one style and stigma 

 surmount the ovary, which may therefore be considered to be composed of a single 

 carpel which rises up from the floral axis as an annular zone. In Piperaceae 

 however the stigma, which is sessile on the apex of the ovary, is often placed 

 obliquely or divided into several lobes ; and this, like the two or four styles 

 which surmount the ovary of Naias ^, indicates that the ovary is not composed of 

 one but of several carpels, which first make their appearance, like the leaf-sheaths 

 of Equisetum, as an unbroken ring, which only at a later period becomes resolved 

 at its upper margin into teeth. This hypothesis appears the more admissible 

 since, in other Angiosperms where a comparison with nearly allied forms justifies 

 us in inferring a number of coherent carpels, these carpels originate as an un- 

 divided annular zone which developes into the ovary, style, and stigma ; as, for 

 instance, in Primulaceae (Fig. 360). In Polygonaceae, on the other hand, where 

 the ovary also forms eventually a closed cavity containing the central ovule (Fig. 

 361), the cohesion of two or three carpels to form the ovary may not only be 

 recognised from the corresponding number of the styles and stigmas; but separate 

 carpels appear at first distinct on the floral axis, and only amalgamate in the course 



1 Magnus, Zur Morphologic der Gattung Naias (Bot. Zeit. 1869, p. 772).— Rohrbach, Ueber 

 Typha (in Sitzungsber. des Gesells. naturf. Freunde Berlin Nov. 16, i869).-Hanstein u. Schmitz, 

 Ueber Entwickelung der Piperaceenbliithen (Bot. Zeit. 1870, p. 38). 



2 I am unable to understand why Magnus calls the coating of the ovary ' perianth.' 



