THE POLYPETALOUS ORDERS. 371 



CHAPTER IV. 



ILLUSTRATIONS OF THE NATURAL ORDERS OR FAMILIES. 



Series I. FLOWERING, OR PH^ENOGAMOUS PLANTS. 



PLANTS furnished with flowers (essentially consisting of stamens 

 and pistils), and producing proper seeds (110, 414). 



Class I. EXOGENOUS OR DICOTYLEDONOUS PLANTS. 



Stem consisting of a distinct bark and pith, which are separated 

 by an interposed layer of woody fibre and vessels, forming wood 

 in all perennial stems : increase in diameter effected by the annual 

 deposition of new layers between the old wood and the bark, which 

 are arranged in concentric zones (189-205), and traversed by 

 medullary rays. Leaves commonly articulated with the stem 

 (310), their veins branching and reticulated (276). Sepals and 

 petals, when present, more commonly in fives or fours, and very 

 rarely in threes. Embryo with two or more cotyledons (633, 640). 



Subclass 1. ANGIOSPERMOUS EXOGENOUS PLANTS. 



Ovules produced in a closed ovary, and fertilized by the action 

 of pollen through the medium of a stigma. Embryo with a pair 

 of opposite cotyledons (633). 



Division I. POLYPETALOUS EXOGENOUS PLANTS. 



Floral envelopes consisting of both calyx and corolla ; the petals 

 distinct.* 



CONSPECTUS OF THE ORDERS. 



Group 1. Ovaries several or numerous (in a few cases solitary), distinct, 

 when in several rows sometimes cohering in a mass, but not united into 

 a compound pistil.- Petals and stamens hypogynous. Seeds albuminous. 



* Stamens or pistils (one or both) numerous or indefinite. 

 Herbs, without stipules. RANUNCULACE^E, p. 376. 



* Some cases of polypetalous flowers also occur in the orders Ericacese, 

 Aquifoliacea?, and Plumbaginaceae, which are placed in the Monopetalous 

 part of the scries ; and some genera of several orders placed here are apeta- 

 lous, such as Anemone, &c. 



