PART FOURTH. 



DESCRIPTIVE BOTANY; OE, PHYTOLOGY. 



COMPRISING 



THE FLORA OF THE UNITED STATES AND CANADA 



(WITHIN THE LIMITS MENTIONED IN THE PREFACE). 



Sub-Kingdom, PHtENOGAMIA on FLO WEEING 

 PLANTS. — Vegetables having ;m axial development, leafy 

 appendages and true flowers, their substance composed of cel- 

 lular, spirovascular, and woody tissue ; their flowers with mani- 

 fest stamens and pistils, and producing seeds with an embryo. 

 (For sub-kingdom Cryptogamia or Flowerless Plants, see page 

 810). 



Province, EXOGENJ] on DICOTYLEDONOUS 

 PLANTS. — Plnenogamous plants having a stem composed 

 of a central column of pith enclosed with wood and bark, 

 the latter exterior ; growing by the addition of concentrio 

 layers external to the wood, internal to the bark. Leaves 

 mostly net-veined. Flowers very generally 5-merous, rarely 

 3-merous. Embryo with two or more opposite cotyledons. 

 (Province Endogena) or Monocotyledonous plants, see page 

 666.) 



Class I, ANGIO SPERMS.— Exogenous plants with net- 

 veined leaves. Pistils complete, having stigmas for the 

 reception of the pollen, enclosing the ovules within an 

 ovary which becomes at maturity a seed-vessel enclosing 

 the seeds. Cotyledons only two. (Class II. Gymno- 

 spermaa, with no stigmas, naked seeds, and leaves not net- 

 veined, see page 659.) 



Cohort 1, DIALYPETAL.E on POLYPETALOUS 

 EXOGENS. — Plants having a double perianth, consist- 

 ing of both calyx and corolla, the latter composed of 

 distinct petals, rarely abortive. (Cohort 2. Gamope- 

 talae or Monopetalous Exogens, page 393. Cohort 3, 

 Monochlamydeaa or Apetalous Exogens, page 601.) 



