285^ CLASSIFICATION". 



but a single genus (as PlatanaceaB, the Plane-trees), while 

 others comprehend a hundred, or even a thousand, as 

 Umbelliferas, and Oompositae. 



Cohorts, etc. — Again, the orders, by some one or few 

 traits which they possess in common, are marshaled into 

 Cohorts ; the cohorts into Classes, and the classes into 

 Provinces. 



Subkingdoms.— Viewed as a whole, the Vegetable 

 Kingdom subsists in two grand divisions, called the Pheno- 

 gamia and Cryptogamia, as first shown by John Eay of 

 England, 1682. This division depends on the habitual pres- 

 ence or absence of visible flowers, and is confirmed by im- 

 portant differences of internal structure, and of seeds. (See 

 pp. 16, 27, 43.) 



Provinces. — Each subkingdom is again divided into two 

 provinces. 1st. The province Exogens includes all such 

 flowering plants as have seeds with 2 or more cotyledons in 

 the embryo, wood growing by external layers, leaves net- 

 veined, and their flowers never (or very rarely) 3-parted. 

 2d. The province Endogeus includes all flowering plants 

 which have seeds with one cotyledon only, wood growing by 

 internal accretions, leaves parallel-veined, and flowers habit- 

 ually 3-parted. 3d. The province Acrogens includes all 

 flowerless plants with stems growing in length, or at the 

 point {akros) only ; as Ferns and Mosses. 4th. The prov- 

 ince Thallogens, is composed of plants of the lowest orders, 

 growing indefinitely in shapeless expansions with no distinct 

 axis ; as Lichens. 



Classes.— The subdivisions of the provinces are called 

 Classes ; there are two of each. 1st. The Exogenous Angio- 

 sperms have flowers with stigmas, and seed-vessels inclosing 

 the seeds. 2d. The Exogenous Gymnosperms are naked- 

 seeded, having neither stigmas, nor pericarp ; as Pinus. 



