158 



SYSTEMATIC BOTANY. 



Flowerless Plants producing in vegetation 

 a thallus an indefinite expansion or mass, 

 with no distinction of stem, leaf, or root, 

 composed of cellular tissue only (Lichens, 

 Fungi, etc.) 



it is naturally divided into two Provinces, founded upon then 

 mode of vegetation. The Acrogens include those tribes which 

 make some approach toward the Phaenogams, while the Thallo- 

 gens include the lowest tribes of the vegetable kingdom. They 

 are thus distinguished 



ACROGENS (axpov i the summit or point, THALLOGENS (5iXXov, green expansion, 

 j Svvaw) 



Flowerless Plants having a regular stem 

 or axis, which grows by the extension of 

 the apex only, generally with leaves, and 

 composed of cellular tissue and scalar! form 

 ducts (Ferns, Mosses, Club-mosses, Horse- 

 tails, etc.) 



517. Classes of the Flowerless Plants. For the sake ot 

 analogy and an advantageous comparison with the Phaenogams, 

 we may also regard these two provinces of the Cryptogams in 

 the light of Classes founded upon their different modes of fruit- 

 bearing. Thus the Acrogens constitute the class 



ANGIOSPORJE (ayysiof, OVopot), or Angiosporen : 



Acrogenous plants, producing their spores in sporangia (vessels) which b&rot 

 when the spores are mature. 



And the Thallogens constitute the class 



GYMNOSPORJG (yu/xvog, OVopa), or Gymnospores : 



Thallogenous plants reproduced by spores, which are produced in parent cell^ 

 either forming a part of the vegetating thallus, or growing upon the surface of some 

 definite region of the thallus. 



518. The class ANGIOSPORES is divided into three cohorts (or 

 Alliances according to Lindley) : 



Lycopodales. Acrogens with vascular tissue, spores of two kinds, and spore-cases axil- 

 lary or radical, one many-celled. Plants with well-developed leaves. (Lycopodiacese, 

 Marsileaceae.) 



Filtcales. Acrogens with vascular tissue, spores of but one kind, spore-cases borne on 

 the margin, back, or summit of the frond, one-celled, usually girded by an elastic ring. 

 Plants leafy or sheathed. (Equisetaceae, Filices.) 



Muscales. Acrogenous plants mostly cellular, with two kinds of floral organs (antheri- 

 dia and archegonia), and spore-cases (thecae) either hooded or immersed in the substance 

 of the frond. (Mosses, Hepaticae, etc.) 



519. The class GYMNOSPORES also consists of three cohorts: 



Lichenales. Thallogens growing in air, crustaceons, without mycelium, including 

 spores plunged in the thallus as well as in shields. (Lichens.) 



Algales. Thallogens living in water or very damp places, cartilaginous, brightly colored, 

 without mycelium, nourished through their whole surface. (Algae, or Seaweeds.) 



Fungales. Thallogens fructifying in the air, never green, nourished by their own my 

 celium, which is Immersed in, and feeds upon decaying substances. (Fungi.) 



