436 Rev. S. Ilaughton on the General Law of Phyllutaxis 



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

 whorls of 1 each. Divergence = ^. 



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

 of 9 each. Divergence = y g. 



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 = ^. 



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

 whorls of 7 each. Divergence = j^^. 



This plant resembles some of the Kiltorcan plants which have 

 been called Knorria. 



11. L. yriddides. Mauritius. Leaves of stem in alternate 

 whorls of 2 each. Divergence = \. 



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

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



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

 alternate whorls of 4 each. Divergence = ^. 



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 = y'g. 



This plant bears a close external resemblance, on a smaller 

 scale, to Lepidodendron dichotomum. 



Sufficient evidence has been adduced to prove that the Lyco- 

 podiacefe 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 \. 



14- 



I 

 8" 



1_ 

 1 6* 



1 

 TTI* 

 _1_ 

 22* 



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 : — 



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

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

 leaves. 



