BASIS OF CLASSIFICATION. 



17 



F. The Bract (L. scale) is a transformed leaf, on the 

 peduncle or at its base. It is conspicuous in the Rose 

 and Carrot. In the Hollyhock and Cotton (Fig. 10) the 

 large bracts just below the flower exactly resemble a calyx ; 

 but the true calyx is within ; and we can always tell the 

 difference between bracts and sepals, because bracts are 

 never on the torus. 



31. Basis of Classification. — The ruling principle in 

 all classification is the Mela- 

 tive Value of Characters, the 

 most constant (enduring) 

 characters taking the highest 

 rank. In Botany these are 

 found in the flower, but es- 

 pecially in the embryo ; there- 

 fore The condition of the 

 embryo is the basis of classifi- 

 cation. The rules of value 

 are as follows : 



I. The Embryo: A. The 

 absence (Cryptogamia) or 

 presence (Phanerogamia) of 

 differentiated organs such as 

 cotyledons, radicle, and plu- 

 mule; 



B. The absence (Gymno- 

 spernise) or presence (An- 

 giospermae) of an ovary ; 



C. The number of coty- 

 ledons (Monocotyledonse, 

 Dicotyledonse). 



II. The Petals : A. 

 Their absence (Apetalse) or d". ana at its base 

 presence (Petalse). B. Their cohesion (Monopetalae) or 

 separation (Polypetalse). 



III. The Stamens : Their manner of insertion, giving 

 rise to the distinctions Ovary Free, Ovary Adherent, etc. 



IV. The Peeispeem : Its presence or absence ; Its 

 nature. 



V. The Radicle : Its direction. 



b 2* 



Fra. 10. — Indian Cotton (Gosaypvum tri- 

 cuspidalum), fls. on peduncles; bracts just 

 below the calyx, simulating a calyx ; 

 smaller bracts lower down on the jiedun- 



