2 ANALYSIS OF POLYPETALOUS ORDERS. 



LOPES commonly arranged in a quinary (sometimes binary or 

 quaternary, but very rarely in a ternary) manner, sometimes in- 

 complete or wanting. Ovules enclosed in a pericarp, fertilized 

 by the action of pollen through the medium of a stigma, and 

 finally becoming seeds. Embryo with 2 (rarely more) opposite 

 cotyledons ; the radicle in germination elongating directly into a 

 root. 



Section I. POLYPETALOUS EXOGENOUS PLANTS. 



Thalamiflorse and Calyciflorse, DC. 



Floral envelopes consisting of both calyx and corolla ; the latter 

 composed of distinct petals.* 



Artificial Analysis of the Polypetalous Exogenous or* 

 ders, lohich are represented in the Flora of JVorth 

 America, 



I. OVARIES SUPERIOR, OR PARTLY SO. 



§ 1. Ovaries more than one, distinct {when in several whorls sometimes 

 aggregated or coalescent into a mass, but not syncarpous.) 



Leaves (emersed ones) centrally peltate. Water- 

 plants. 

 Torus turbinate, enclosing the ovaries in sepa- 

 rate hollows. 9. Nelumeiace^. 

 Torus inconspicuous. Stamens 6-36. 7. Cabombace;e. 

 Leaves not centrally peltate. 



Stamens numerous. 

 Ovaries (achenia) enclosed in the subglobose 

 calyx-tube, numerous. 

 Leaves opposite, not stipulate. 50. Cai,ycanthace£. 



Leaves alternate, stipulate. 49. § Rose^;. 



Ovaries not enclosed by the calyx-tube. 

 Petals and stamens perigynous. 49. RosacejE. 



Petals and stamens hypogynous. 

 .Estivation of the calyx valvate. 



Leaves alternate. Stamens monadelphous. 38. Malvace^. 

 Leaves opposite. Stamens distinct. 

 .Estivation of the calyx imbricated. 



Herbs with acrid juice. Flowers perfect. I. RANUNcuLAnE^. 



Climbing shrubs. Flowers small, dicecious. 5. MENispERMACEiE. 

 Trees or shrubs (bitter and aromatic). — 

 Flowers large, perfect. Anthers adnate. 

 Anthers (short) extrorse. Sepals per- 

 sistent. Albumen ruminated. 3. Anonace^. 

 Anthers (long) introrse. Albumen solid. 2. Magnoliace^. 



* The student should bear in mind that the division of Exogenous plants into 

 Polypetalaj, Monopetalfe, and Apetalai, however convenient, is in a considerable 

 degree arbitrary ; and that polypetalous orders often contain apetalous genera and 

 species ; the petals, moreover, arc occasionally mo^e or less combined. 



