426 EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



limb four-toothed. Petals four, valvate in aestivation. Stamens 

 four, alternate with the petals. Styles united into one. Fruit a 

 two-celled drupe. Ex. Cornus, the Dogwood. Chiefly remark- 

 able for their bitter and astringent bark, which in this country has 

 been substituted for Cinchona. The peculiar principle they con- 

 tain is named Cornine. Cornus Canadensis (Fig. 240) is a low 

 and herbaceous species. 



Division II. MONOPETALOUS OR GAMOPETALOUS EXOGENOUS 



PLANTS.* 



Floral envelopes consisting of both calyx and corolla : the petals 

 more or less united (corolla gamopetalous). 



CONSPECTUS OF THE ORDERS. 



Group 1. Ovary coherent with the calyx, two- to several-celled, with one or 

 many ovules in each cell Seeds albuminous, with a small embryo. Sta- 

 mens inserted on the corolla. Leaves opposite. 



Stipules wanting. CAPRIFOLIACE.E, p. 428. 



Stipules interpetiolar (or leaves whorled). RUBIACE.E, p. 429. 



Group 2. Ovary coherent with the calyx, one-celled and one-ovuled; rarely 

 three-celled with two of the cells empty. Seeds with little or no albu- 

 men. Stamens inserted on the corolla. Calyx a mere ring, crown, or 

 pappus, or obsolete. Fruit like an achenium. 



Stamens distinct. Seed suspended. 



Stamens 3 or fewer. VALERIANACE.SE, p. 431. 



Stamens 4. Heads involucrate. DIPSACE.S:, p. 432. 



Stamens syngenesious. Seed erect. COMPOSITE, p. 433. 



Group 3. Ovary coherent with the calyx, with two or more cells and numer- 

 ous ovules. Seeds albuminous. Stamens inserted with the corolla (epi- 

 gynous) : anthers not opening by pores. 



Corolla irregular. Stamens united in a tube. LOBELIACE^:, p. 435. 



Corolla regular. Stamens distinct. CAMPANULACEJE, p. 436. 



Group 4. Ovary free from the calyx, or sometimes coherent with it, with 

 two or more cells and numerous ovules. Seeds albuminous. Stamens 

 inserted with the corolla, or rarely coherent with its base, as many, or 

 twice as many, as its lobes : anthers mostly opening by pores or chinks. 



* Cucurbitaceee, placed in the Polypetalous series, are commonly somewhat 

 gamopetalous : so are some exotic CrassuJaceae, &c. 



