16 The New York IState Collcfjc of Forcslry 



which have certain gross features in common, then successively 

 into smaller divisions and ultimately into genera and species. 

 The characters enumerated under successive divisions are in- 

 creasingly specific and of narrower latitude. The divisions of 

 such a classification are listed below, those in "italics" often 

 being omitted. Clarity is rendered more certain by classifying 

 the Paper or Canoe Birch according to this plan: 



Kingdom Vegetable. 



Sub-kingdom Spermatophyt.es. 



Class Angiosperms. 



Sub-class Dicotyledons. 



Series ArcMcMamycLeae. 



Sub-series Apetalae. 



Order Fagales. 



Sub-order 



Family Betulaeeae. 



Tribe 



Genus Betula. 



Species alba. 



Variety papyrif era. 



The Vegetable Kingdom is divided into four sub-kingdoms, viz. : 



Thallophytes algae, fungi, bacteria, etc. • 



Bryophytes liverworts and mosses. 



Pteridophytes ferns, scouring rushes, horsetails, club-mosses, 



and quillworts. 



Spermatophytes all seed plants, including conifers and decidu- 

 ous trees. 



A proper conception of the limits of these groups will lead 

 to a better understanding of trees and the relation which they 

 bear to other plants. 



Thallophytes constitute the lowest division of the vegetable 

 kingdom and include the simplest forms of plants: The plant 

 body or thallus exhibits little variation or specialization in struc- 

 ture (though often a wide range of form) and usually carries 

 on its life activities either in water or on a moist substratum. 

 Included in this group are the aJgac (pond scums, seaweeds, etc.), 

 and the fungi (Mushrooms, bracket fungi, etc.), both of which 

 exhibit a remarkable variation in the form and size of tlie 

 thallus but extreme simplicity in its structure. Many of the 

 simplest Thallophytes are unicellular and some are free swim- 

 ming and resemble minute animals. Sexuality has become well 

 developed in may forms while in others it is totally lacking. 



Bryophytes are best represented by the mosses although a 



