436 Rev. S. Haughton on the General Law of Phyllotaxis 



7. L. Selago. Canton Ticino. Leaves of stem in alternate 

 whorls of 4 each. Divergence = J. 



8. L. reflexum. Pacific. Leaves of stem in alternate whorls 

 of 9 each. Divergence = y 1 ^. 



This plant has a striking external resemblance to Lepidodendron 

 minutum and to some of the smaller Cyclostigmas of Kiltorcan. 



9. L. quadrifasciatum. Leaves of stem in alternate whorls of 

 2 each. Divergence = J. 



10. L. verticillatum. Mauritius. Leaves of stem in alternate 

 whorls of 7 each. Divergence = j 1 ^. 



This plant resembles some of the Kiltorcan plants which have 

 been called Knorria. 



11. L. grido'ides. Mauritius. Leaves of stem in alternate 

 whorls of 2 each. Divergence = J. 



12. L. flagellarium. New Zealand, North Island. Leaves of 

 stem in alternate whorls of 2 each. Divergence = J. 



13. L. varium. Lord Auckland's Islands. Leaves of stem in 

 alternate whorls of 4 each. Divergence = J. 



14. L. catharticum. Peru. Leaves of stem in alternate whorls 

 of 2 each. Divergence = . 



15. L. (n. sp.). Quito. Leaves of stem in alternate whorls of 

 8 each. Divergence = T 1 ^. 



This plant bears a close external resemblance, on a smaller 

 scale, to Lepidodendron dichotomum. 



Sufficient evidence has been adduced to prove that the Lyco- 

 podiacea? follow the geometrical law of alternate whorls. Col- 

 lecting together the results, we find the following angles of 

 divergence : 



In 6 species an angle of . 



5 TS- 



* 



TS' 



i 1 



TB' 



>') W 



These numbers correspond with whorls consisting of 2, 4, 8 

 1 eaves, being powers of 2, and whorls containing prime numbers 

 of leaves 7, 9, 11. 



The prime whorls could not give rise to any of the known 

 phyllotaxes of alternate-leaved plants ; but the whorls of powers 

 of 2 may do so as follows : 



(1). The whorl of 2, by suppression of the alternate whorls, 

 gives the phyllotaxis = ^. Reduction of 50 per cent, of 

 leaves. 



