112 



ELEMENTS OF STRUCTURAIi BOTANY. 



o 

 R 



a 



3 



iri 



a 

 y 



So far, then, our classification is as follows : 



f Sub-class l—Arjgiosp«.rLQ3 

 Polypetalous Division. 

 Class I.— Exogens •• -i GamopetaUms " 



Apetalmis 

 (^ Sub-class 2-Gymiiospt'ring 

 rSpadiceous Division. 



Series I. 



Phanero- 

 gams 



Class II.— Endogens-i Fetaloideous Division. 

 (^Glumaceous Division, 



/'Class III.— Acrogens. 

 Series II. i 



-I Class IV.— Anophytes. 

 Cryptogams. I 

 L L Class V.-ThaUophytes. 



Each of the I)ii-isio)is is sub-divided into z uumbur 

 Families or Orders ; each Order into a number 



of 

 of 



r 



Genera ; and each Genus into Species. A species is 

 the sum c " all the individual plants v.hose resemblances 

 in all essential respects are so great as to warrant the 

 belief that they have sprung from one common stock. 

 De Candolle has this statement : " We unite under ',he 

 designation of a species all those individuals that mutu- 

 ally bear to each other so close a resemblance as to 

 allow of our supposing that they may have proceeded 

 originally from a single being or a single jmir." We 

 may also speak of each one of these individual plants as 

 a species. For example, you may say, after finishing 

 the first lesson of this book, that you Jiave examined a 

 species of Buttercup. Mere differencesof colour or size 

 are not sufiicient to constitute diflferent species. The 

 Balsams of our gardens, for instance, are of various 

 colours, and the plants vary greatly in size, yet they all 

 belong to one species. These minor differences, which 

 are mainly the rer,ult of caro aiid cultivation, give rise 

 to varieties. These are of great interest to the horticul- 



