ANGIOSPERMS. 



SK 



3. Basal or axillary, springing from the base of the upper side of the carpel 



or from the axil of the carpel, as in Ranunculus, Sedum, Zannichellia 

 according to Warming 1 . 



//. Ovules borne on the axis and springing from the prolongation of the floral 

 axis within the ovary, the carpels themselves being sterile ; these are 



4. Lateral, when they arise beside or below the apex of the axis which either 



rises as a column and bears numerous ovules, as in Fig. 309, or ceases to 

 grow after forming one ovule, so that this may appear to be terminal, as in 

 Fig. 310. 



5. Terminal, when the apex of the axis itself becomes the nucellus, as in Fig. 

 308, the Piperaceae, Naias, etc. 



The question, to which of these types the ovules of any given plant belong, must 

 be decided in each individual case, but the ovules that are marginal on the carpels are 

 much the most common in Angiosperms, while the superficial and the axillary 

 positions are confined to single families or genera. If we compare the position of the 

 ovules in Angiosperms and Gymnosperms, we find that the ovules of the Cycadeae 

 belong to the marginal class, those of Dammar a and Araucaria to the superficial, 

 those of the Cupressineae to 

 the axillary ; those of Gingko 

 are lateral upon the axis, those 

 of Taxus are terminal. Similar 

 varieties of position are found 

 in the sporangia of the Vascular 

 Cryptogams, though none are 

 terminal upon the axis; the 

 sporangia of Ophioglossum, for 

 example, are produced laterally 

 on a leaf, those of many Ferns 

 are superficial on a leaf, those 

 of Lycopodium and Selaginella 

 are axillary or basal; the 

 latter may also be considered 

 as being upon the axis and 

 lateral, of which kind the 

 sporangia of the Psilotaceae most be regarded as the most striking examples. 



The ovules are sometimes rudimentary; those of the Balanophoreae and 

 Santalaceae have no integuments, the nucellus being naked and in many species 

 consisting of only a few cells. The same is the case with the Loranthaceae 2 , where 

 the ovules are produced, as in the Santalaceae, from an axial placenta ; but the latter 

 becomes so closely united at a very early period with the tissue of the carpel, that 

 when the flower opens it is no longer possible to distinguish the ovules by any 



1 Warming, Recherches sur la ramification des Phanerogames, Kopenhagen, 1872, page xxii, 

 Taf. xi, Fig. i-io. Axillary ovules are as little to be regarded as shoots (stems) as are the axillary 

 sporangia of the Lycopodieae and Selaginelleae ; and there is as little ground for regarding mar- 

 ginal ovules as leaf-tips or pinnae. 



2 Treub, Observations sur les Loranthacees (Ann. du jard. bot. de Buitenzorg, 1881). 



[a] 



FIG. 318. Funkia cot-data. A transverse section of young superior trilocular 

 ovary ; two ovules SK are visible in each compartment growing from the revolute 

 margins of the carpels, g vascular bundles surrounded by transparent parenchyma. 

 Cyoung ovule in optical longitudinal section ; KK tissue of the nucellus, z':' integument, 

 ia outer integument. A is slightly, C is very highly magnified ; the dark-coloured cell 

 is the mother-cell Of the embryo-sac. 



