78 



SYSTEMATICAL BOTANY. 



II. ANALYTICAL METHOD. 



625. THIS is founded upon the common process of analysis 

 that is unconsciously employed by the human mind. In all 

 cases the mental operation by which one thing is distinguished 

 from another, consists in a continual contrast of characters. 

 For instance, in a mass of individuals we distinguish one set 

 which is coloured, and another which is colourless ; of those 

 that are coloured we distinguish red, black, blue, and green ; 

 of the red, some are square, others are round ; of the round, 

 some are sculptured on their surface, others are even : and so 

 we proceed, analysing the subject by a constant series of con- 

 trasts, until we have arrived at a point beyond which no 

 analysis can go. 



626. The following pages contain such an analysis of the 

 principal natural orders of plants. The method may be 

 equally applied to genera and species, and is an instructive 

 process if employed by way of exercise to the mind, and for 

 the purpose of rendering distinctions definite : 



1. Plants with visible flowers and 

 seeds . . . .2 



Plants with visible flowers and 

 spores . . . RHEANTHS. 



Plants without flowers . .261 



2. Leaves netted. Wood in con- 

 centric layers .- . .3 



Leaves straight-veined. Wood 

 confused .... 239 



Leaves straight-veined. Wood 

 in concentric layers . . 237 



3. Flowers having both calyx and 

 corolla . ...' . .4 



Flowers having a calyx only, or 

 none . . 



4. Petals distinct . 

 Petals united 



5. Stamens more than 20 . 

 Stamens fewer than 20 



6. Ovary inferior, or partially so 

 Ovary superior . 



7. Leaves furnished with stipules . 8 

 Leaves without stipules . .10 



8. Carpels more or less disunited POME.E. 

 Carpels consolidated . 9 



119 

 5 



186 

 6 



36 



7 



15 



9. Placenta central LECYTHIDACEJE. 

 Placenta parietal . HOMALIACEJE. 



10. Carpels distinct . ANONACE^. 

 Carpels consolidated . .11 



11. Placenta spread over the septa 



Placenta parietal .12 



Placenta in the axis . .13 



12. Petals definite in number LOASACE.E. 

 Petals indefinite . CACTACE^E. 



13. Leaves with transparent dots 



MYRTACE^. 

 Leaves dotless . . .14 



14. Petals indefinite . MESEMBRYACE^;. 

 Petals definite . PHILADELPHACE.*;. 



15. Leaves with stipules . .16 

 Leaves without stipules . . 24 



16. Carpels disunited . .17 

 Carpels consolidated . .18 



17. Stamens hypogynous MAGNOLIACE^E. 

 Stamens perigynous . ROSACES. 



18. Placenta parietal . BIXACE^J. 

 Placenta in the axis . .19 



19. Estivation of calyx imbricated . 20 

 Estivation valvate . 22 



