THE EMERGENCE OF THE FLORAL WHORLS. 189 



superposed to the petals, and therefore autipetalous, then the 

 above term is used : for the rule is that the calycine whorl 

 should be outermost and emerge first ; then the petaline, which 

 usually takes a position higher up on the axil ; and, in at 

 least most of the genera and orders where obdiplostemony has 

 been noticed in the completely developed flower, it is simply 

 due to the petaline whorl of filaments being, so to say, thrust 

 outside the level of the calycine whorl by the protruding 

 buttress-like bases of the carpels, as in Geranium pratense. 

 This is still more the case in Oxalis, where, as in Geranium, 

 the sepaline stamens become the taller set, the petaline the 

 shorter ; and the position of the former being more internal 

 than usual, ajDparently in consequence of the appendages 

 which grow on the outer side of the filaments.* 



Again, the order of emergence may be the same as usual, 

 namely the sepaline stamens first, then the petaline ; but 

 the position of the latter, instead of being within as is 

 the rule, may be apparently on exactly the same plane as 

 the sepaline, as in Heaths. Since, however, 

 they do not emerge simultaneously, but one 

 set is intercalated between the other, or even 

 outside of it (Fig. 51), this order of appear- 

 ance is, to my mind, a sufficient proof that 

 they do not really belong to the calycine Fig. 51. — Diagram 



whorl ""^ emergence of 



TTAJ.W1X. petaline stamens 



There is no greater difficulty in under- ^[de'''?he"sepai"n; 

 standing this, than in seeing that a compres- (after Payer), 

 sion of the internodes of opposite and verticillate leaves has 

 taken place when double the usual number are present in 

 a whorl. Thus privet has sometimes four leaves at one node, 

 forming a quaternary whorl, and all on the same plane ; and 



* According to Frank, in Oxalideoe and Gei'aniacece, it is the auti- 

 petalous stamens -vvliich are developed first. See above, p. 150. 



