166 



VEGETABLE KINGDOM. 



2. Anogens. — Consisting wholly of cellular tissue ; growing up in 

 short, leafy stems; as (1) Musci, or Mosses; (2) Liverworts. 



3. Acrogens. — Consisting of vascular tissue in part, and growing 

 upward ; as (1) Ferns ; (2) Lycopodia (Ground-Pine) ; (3) Equiseta ; 

 and including many genera of trees of the Coal period. 



II. Pelenogams. — Having (as the name implies) distinct flowers 

 and seed ; as the Pines, Maple, and all our shade and fruit trees, 

 and the plants of our gardens. They are divided into — 



1. Gymnosperms. — Having the flowers exceedingly simple, and the 

 seed naked, — the seed being ordinarily on the inner surface of the 

 scales of cones; growth exogenous, the trees having a bark and 

 rings of annual growth (fig. 195) ; as the Pine, Spruce, Hemlock, etc. 

 The name gymnosperm is from the Greek for naked seed. Gymnosperms 

 include (1) Conifers; (2) Cycads (p. 418) ; and (3) Sigillarids (p. 335). 

 Figs. 195-204. 



Plants. — Fig. 195, section of exogenous wood ; 196, fibres of ordinary coniferous wood (Pinui 

 Strobus), longitudinal section, showing dots, magnified 300 times ; 197, same of the Austra- 

 lian Conifer, Araucaria Cunninghami ; 198, section of endogenous stem. 



Figs. 199 to 204, Diatoms highly magnified; 199, Pinnularia peregrina, Richmond, Va. ; 200, 

 Pleurosigma angulatum, id; 201, Actinopticus senarius, id; 202, Melosira sulcata, id; o, 

 transverse section of the same ; 203, Grammatophora marina, from the salt water at Ston- 

 ington, Conn. ; 204, Bacillaria paradoxa, West Point. 



The wood of the Conifers is simply woody fibre without ducts, 

 and in this respect, as well as in the flowers and seed, this tribe 

 shows its inferiority to the following subdivision. The fibre, more- 

 over, may be distinguished, even in petrified specimens, by the dots 

 along their surface as seen under a high magnifier. The dots look 

 like holes, though really only thinner spaces. Fig. 196 shows these 

 dots in the Pinus Strobus. In other species they are less crowded. 

 In one division of the Conifers, called the Araucarice, of much geo- 

 logical interest, these 'dots on a fibre are alternated (fig. 197) ; and 

 the Araucarian Conifers may thus be distinguished. 



2. Angiosperms.— Having regular flowers and covered seed; growth 

 exogenous, the plants having a bark and rings of annual growth 

 (fig. 195) ; as the Maple, Elm, Apple, Eose, and most of the ordinary 



