DICOTTLEDONES. 193 



printed in smaller type, are accorded to those Orders which either are not 

 marked by very decided characters, or which do not demand so much 

 attention from the beginner. In most cases the views of other botanists 

 as to the position and limitation of the groups are briefly mentioned. 

 Tinder each Order are placed the names' of one or more genera which 

 furnish good illustrations and which are generally accessible for practical 

 examination. 



CHAPTER III. 



SYSTEMATIC DESCRIPTION OF THE NATURAL ORDERS. 

 THE VEGETABLE KINGDOM. 



SUBKINGDOM I. PHANEROGAMIA, or FLOWERING PLANTS. 



Plaiits producing stamens and pistils in association or separately, 

 and forming seeds containing an embryo. 



CLASS I. DICOTYLEDONES. 



Flowering Plants, with stems (when woody) having pith and 

 bark separated by a compact layer of wood, which, in perennial 

 plants, receives annual additions on the outside, beneath the bark ; 

 leaves with the ribs mostly distributed in a netted pattern and 

 generally diminishing in size as they branch ; parts of the floral 

 circles mostly 5 or 4, or some multiple of those numbers, rarely 3 ; 

 embryo with a pair of cotyledons and a radicle, which is developed 

 into a tap-root in germination. The typically complete floral 

 formula, supposing the parts to be uncomplicated by adhesions, 

 irregular growth, multiplication, &c., is S5 P5 A 5 G5, in regular 

 alternation. 



SUBCLASS I. ANGIOSPEEMIA. 



Flowering Plants, with the ovules formed in closed ovaries. 

 Endosperm formed after fertilization. Pollen-cells not dividing 

 prior to the emission of pollen- tubes (see under " Reproduction "). 



Division I. Polypetalae. 



Petals distinct, rarely absent or united. 



Exceiaf ions. Hooker notes the following exceptions. Apetalous flowers 

 occur in some species of Menispermaceee, Caryophyllaceas, Malvaceae, 

 feterculiaceee, Tiliaceae, Rutaceae, Simarubaceae, Burseraceae, Olacacese, 

 Celastraceae, Saxifragaceae, Crassulaceae, Myrtaceae, Passifloraceae. Ape- 

 talous flowers also may be met with in some Ranunculaceae, Maguoliaceae, 

 Berberidaceae, Sarraceniaceae, Papaveraceae, Cruciferae, Canellaceae, 



o 



