XCViii NATURAL ARRANGEMENT. 



GROUP 4. Flowers perfect, entirely destitute of calyx as well as 

 corolla. Embryo minute, inclosed in a persistent embryo-sac at 

 the apex of the albumen. SAURURACEAE. p. 256. 



GROUP 5. Flowers perfect or diclinous, often destitute of "both 

 calyx and corolla. Submersed or floating herbs. 



Flowers monoicous. 



Fruit 1-cetted, 1-seeded. CERATOPHYLLACEAE. p. 257. 

 Fruit 4rceUed, 4-seeded. CALLITRICHACEAE. p. 257. 



Flowers mostly perfect. 

 Capsule several-celled, several-seeded. PODOSTEMACEAE. p. 258. 



GROUP 6. Flowers monoicous or dioicous, not amentaceous. Fruit 

 capsular or drupaceous, with 2 or more cells, and mostly 1 seed in 

 each cell. 



Fruit mostly capsular. Juice milky. ECPHORBIACEAE. p. 258. 



GROUP 7. Flowers monoicous or dioicous; the sterile, and often 

 the fertile ones, in aments, or in heads, clusters, or spikes. Ovary 

 often 2- to several-celled, but the fruit always 1-celled. 



f Fruit drupaceous. Calyx adherent. JUGLANDACEAE. p. 261. 



t f Fruit a nut, involucrate. Calyx adherent. CUPULIFERAE. p. 265. 



f f t Fruit indehiscent, 1-seeded. Flowers all in aments. 



Ovary 1-celled ; ovule solitary, erect. MTRICACEAE. p. 274. 



Ovary 2-cetted, 2-ovuled ; ovule pendulous. BETULACEAE. p. 274. 



1 1 1 1 Fruit deJiiscent, many-seeded. Seeds comose. Flowers all in aments, destitute 

 of calyx. SALICACEAE. p. 276. 



f f f ff Fruit a nutlet, or capsule. Flowers in heads, or ament-lilce clusters, destitute 



of calyx. 



Nutlet clavate, 1-seeded. PLATANACEAE. p. 283. 



1 1 1 1 1 1 Fruit an akene; often inclosed in a baccate calyx. Juice milky, when trees 

 or shrubs. URTICACEAE. p. 283. 



SUB-CLASS II. 



GYMNOSPERMOUS EXOGENOUS PLANTS. 



OVULES, and consequently the seeds, naked, i. e. not inclosed in 

 an ovary ; the carpel being represented either by an open scale, as in 

 the Pines; or by a more evident leaf, as in Cycas ; or else ivanting 

 altogether (the ovule seated in a disk), as in the Yew. Flowers 

 monoicous or dioicous, commonly amentaceous. the stamens often 

 monadelphous. Of course there is neither style nor stigma. CONI i 

 FERAE, p. 289. 



CLASS II. 



ENDOGENOUS PLANTS. 



STEM not distinguishable into bark, pith, and wood ; but the latter 

 consisting of bundles of fibres and vessels irregularly imbedded in 

 cellular tissue ; the rind firmly adherent ; no medullary rays, and 

 no appearance of concentric layers : increase in diameter effected 

 by the deposition of new fibrous bundles which, at their commence- 



