14 PliACTICAL BOTANY. 



pistils may coalesce and consolidate into a compound 

 pistil (as in E,ose-Mallow, Flax, St. John's-wort, etc.) 

 And now, whether we have to do with simple or com- 

 pound pistils, every leaf employed for the formation of a 

 closed pistil is called a j^istilAeaf. But it is more con- 

 venient to use the term carpellary leaf instead of pistil- 

 leaf, since this term can also be applied to open pistils. 

 While the carpels of Angiosperms form closed pistils, 

 those of Gynmosperms remain flat and open, not pos- 

 sessing the power to curve in and unite their edges. Car- 

 jpel is a closed carpellary leaf. 



As stated above, the several whorls of floral leaves — 

 namely, calyx, corolla, stamens, and pistils— are inserted on 

 the receptacle (the uppermost part of the axis) successively, 

 beginning with the calyx, from below upward. It some- 

 times happens that the centre of the receptacle ceases to 

 grow vertically, while the circumference rises higher ; in 

 such case the pistils (or the pistil) will be placed deeper 

 than the other floral circles, or even in an excavation 

 of the receptacle, Ps in the Rose. In theory, the pistils 

 occupy the top, but the top is, as it were, depressed ; in 

 reality it is surpassed by parts of the receptacle, which 

 stood deeper before. 



48. The ANGIOSPEEMS form tliree Divisions: 

 the PolypetaloiiSy the Gamojpetalous^ and the Apetalous. 

 "We here enumerate such of the orders belonging to 

 these divisions, as occur in the l^orthern and Middle 

 States. 



I. PoLTPETALOUS DtVISION. 



49, This division has, as a rule, both calyx and corolla, 

 the latter consisting of separate petals. 



