5 1 6 Ber ridge . — The Structure of the Flower of 
spinous bracts. At the time of flowering, that is, about the middle of July, 
the lower flowers in the tufts borne by the female catkins are flanked by 
sessile buds with well-defined growing points (Fig. 3). These doubtless 
represent the secondary flowers of the dichasia. Round the upper 
terminal flowers of the tufts these outgrowths are so compressed that 
their nature cannot easily be recognized, but they too appear to have 
a growing point round which the young spines cluster, and they also there- 
fore are probably axial in nature. A month later these buds have developed 
into groups of spines as large and conspicuous as the ovaries themselves, 
and in the axils of many of the spines tiny buds appear (Fig. 4). 
Fig. 4. Longitudinal section through ovary and adjacent group of spines, x 30. 
The axial nature of the valve is further indicated by the character 
of the vascular supply. Near its apex, where it is free from the pressure 
of the adjacent ovaries, a circle of six to nine bundles is found, and each spine 
receives a single strand formed by the fusion of two branches from these 
bundles. Near the base, where the valve is flattened between the growing 
ovaries, the bundles are arranged, not in a circle, but in a straight line, 
being evidently displaced by the pressure to which the whole organ is 
subjected. 
Little further development occurs till near the time of fertilization, 
about the middle of the following May, when the ‘ cupule valves ’ begin to 
grow quickly till they entirely cover the nuts with a mass of sharp branch- 
