MULTI JUGATE TYPES. 167 



of regarding them as derived from two or more concurrent genetic 

 spirals did not suit the spiral theory, which demanded one spiral 

 line of growth. 



Such forms of phyllotaxis are, however, not so rare as supporters 

 of the Schimper-Braun hypothesis incline to suppose; they may 

 occur in aU types in which anomalous series are met with, and are 

 most widely distributed. 



They were first fully described by Bravais (loc. cii., p. 96), although 

 examples had previously been noted by Schimper and Braun, and 

 also by De Candolle,* instances being observed in the inflorescences 

 of Dipsacus, Scdbiosa, Arnica, Zinnia, SpilantJius, Piper, Veronica, 

 Verlena ; flowers of Cactus, Calycanfhus ; cones of Pinus maritima, 

 and f oUage shoots of P. palustris. 



The possibility of an approach to bijugate capitula in Composites 

 is further shown by secondary maxima on the variation curves of 

 Ludwig ; while Weisse, out of a batch of 140 plants of Helianthus, 

 obtained one bijugate example (16 + 26). 



' The fact that they may occur in the plant which has already 

 been found to exhibit normal phyllotaxis phenomena most com- 

 pletely, lends additional interest to these constructions. Thus, out 

 of a batch of capitula, collected at haphazard by E. Gr. Broome, two 

 were bijugate, (26 + 42) and (42 + 68) respectively ; the others were 

 quite normal ; j- while out of the total crop of 130 cones on a 

 plant of Pinus pumilo (B. G-. 0., 1900), one cone only was 

 (6/10/16), fig. 60ffi, the rest being normal (5/8/13). 



The bractless spadices of Aroids have already been noted as pre- 

 senting anomalous types of phyllotaxis, and among six inflorescences 

 growing on the same plant of Anthurium Grassinervium, the paras- 

 tichies of three were (8 + 13), a fourth one was irregular, the other 

 two multijugate of the types (6/12/18) and (6/9/15) respectively. 



*De Candolle, Org. Veg., vol. i. p. 326, 1827. "Leaves opposite in spiral 

 pairs " in Globulea obvallata, and also according to Eoeper in Ajuga genevensis. 



+ A case of extreme reduction in Helianthus annuus is of interest : — A seed 

 germinated in a crevice of a stone wall, four feet from the groimd (B. G. 0., 

 1901) and developed a small starved plant : the impoverished terminal capitulum 

 produced 10 ray-florets and 28 disk-florets. The contact curves of these were 

 only (6-1-10) as taken from a section-drawing. The capitulmn was thus bijugate, 

 although the 2-3 foliage leaves beyond the primary decussating pairs were not. 



