THE ANATOMY OF THE STEM OF THE PAPAVER ACE^E. 599 



The vascular strands from the sepals, however, fuse into an outer vascular ring, while 

 the inner ring, at a lower level, opens out once more and its elements unite with the 

 outer ring. The conjoint vascular tissue then splits up into independent strands of 

 various sizes and descends the peduncle in that form. 



In Hypecoum grandiflorum the main stem is short, and most of the aerial region 

 is composed of long slender leaves and floral axes, each of the latter bearing several 

 flowers in racemes. The vascular tissue of each pedicel consists of four bundles prior 

 to the entry of the first leaf-trace. Each pedicel (save the terminal one) receives 

 two leaf insertions before becoming attached to the main axis. Each is unifascicular, 

 and the single strand enters a gap formed by the splitting of the nearest pedicel 

 bundle, the branches fusing with the adjacent axial strands. After the two inser- 

 tions the vascular system of the pedicel thus consists of two large and two small 

 bundles. When, as is sometimes the case, the leaf-traces are trifascicular, each 

 member of the trace maintains its independence and the base of the pedicel then 

 shows the presence of eight bundles. Similarly, the vascular system of the pedicel 

 enters a gap formed for it in the system of the chief axis, one-half of the pedicel 

 system ranging itself on either side of the bract trace. Lateral fusions later on 

 result in the ten to twelve bundles seen in a section of the main axis. 



The inflorescence in Dicentra formosa is a biparous cyme. The vascular system 

 of the youngest pedicel consists of five bundles, that of the subjacent bract of one or 

 three. The vascular tissue of each pedicel fuses laterally into two masses, one on 

 either side of the incoming bract trace, and these three strands are often distinguish- 

 able for some considerable distance. The course of the vascular system in Romneya 

 trichocalyx does not differ materially from that found in Papaver Rhceas. In 

 Corydalis racemosa the vascular tissue of the terminal flower-stalk consists of four 

 independent cords. These fuse in pairs lower down, thus creating two gaps through 

 one of which the vascular system of the next peduncle and its bract enters. The 

 vascular cord of the bract unites with that of the peduncle at the moment of in- 

 sertion. Leger worked out the course of the vascular system in the inflorescence of 

 C. solida, but the arrangement of cords in C. racemosa, C. glauca, and C. capnoides 

 does not quite correspond to his description. In the last-named species the vascular 

 tissue of the terminal flower is represented by a single cord which splits in two just 

 before the entry of the next lower peduncle and bract. 



Some notes may now be added on the insertion of leaf-traces in other species of 

 Papaver and in other genera of the order. 



Papaver dubium— -The leaf-trace entry in this species closely resembles that 

 described for P. Rhodas. Leger says that at the base of the leaf the numerous leaf 

 bundles unite into three, the middle bundle forks, and its two sections fuse with the 

 lateral bundles. He also states that all the bundles of the leaf-trace give off strands 



is 



inwards which either arrange themselves into an arc whose extremities later on fuse 

 with the nearest stem bundles, or remain free and follow an independent course down 



