CONIFERM. 517 



or at a greater height. In Sabina and Callitris quadrivalvis (Fig. 352) only two 

 decussate pairs of carpels separate like a star at the time of flowering ; in Sabina 

 the ovules stand in pairs in the axils of the two lower carpels, right and left of 

 their median line, some of them being frequently abortive ; in Callitris quadri^ 

 valvis a pair occurs on each of the lower carpels and a pair higher up ; but this 

 position can only be explained by further investigation of the history of their 

 development. In Thuja and Cupressus there are three or four decussate pairs of 

 carpels, in Taxodium a still larger number; in Thuja and Taxodium two erect 

 ovules are situated at the base of each of the central pairs of carpels, springing 

 from the right and left of their median line \ in Cupressus there are a considerable 

 number at the base of each carpel. In Arceuthos drupacea and Frenela verrucosa 

 the fruits (in the collection at Wurzburg) consist of alternating whorls of three 

 carpels, opening, in the last species, after the seeds become ripe, like a six-lobed 

 capsule. Each carpel is swollen on its inner side into a thick placenta ascending 

 from the base to the apex, and bearing numerous winged seeds which stand in 

 transverse rows of threes ; there are from four to six of these rows on each carpel, 

 the whole inner side therefore bearing seeds nearly up to the apex. 



So far as the relative positions of the parts of the flower can be explained 



Fig. zS^-— Callitris quadrivalvis ; A female flower (magnified) ; d d two pairs of decussate leaves (carpels) m the 

 axils of which are six ovules (Ks) ; j5 vertical longitudinal section of an ovule through its broader diameter ; AT^the 

 nucellus still without an embryo-sac ; i the tubular elongated integument with the micropyle nt, 



without going back to their earliest stage, a great diversity is thus shown in the 

 two families of Taxineae and Cupressinese ; the ovule is terminal in Taxus^ lateral 

 beneath the summit of the axis in Salisburia, carpellary leaves appearing to be 

 entirely absent. In Podocarpus and Phyllocladus they are indicated indeed, as small 

 scales, the ovules springing from their axils ; but they are small and do not at any 

 time constitute a pericarp. A structure of this kind, in the form of a berry or of a 

 chambered woody fruit, is indeed formed after fertilisation in the Cupressineae, the 

 carpels either becoming fleshy and growing together (as in Juniperus and Sabina), 

 or becoming woody and closing in laterally by their peltate expansions (as in 

 Cupressus, Thuja, and Callitris), or presenting the appearance of the lobes of a 

 unilocular capsule {e.g. Frenela); but the carpels are in these cases at first entirely 

 open. In Juniperus communis the ovules form a whorl alternating with the carpels ; 

 in the other genera they stand in pairs or in larger numbers at their base, or cover 

 the whole of their inner side (as Frenela). 



In the Abietine^ the well-known cones are the female flowers (or rather fruits). 

 The cone is a metamorphosed shoot, its axis bearing a number of crowded woody 

 scales arranged spirally, the ovules arising on them rarely singly, usually in pairs, 

 occasionally in larger numbers. In the Abietineae i^Abies, Picea, Larix, Cedrus, and 



