ACOTYLEDONS. 57 



Acotyledons include cryptogams or flowerless plants ; 

 acrogens, having stems which increase in growth by the 

 summit, and having a peculiar construction ; ferns (Filices) ; 

 Algae or seaweeds ; Fungi, mosses, and lichens (see Plate II. 

 fig. 3, p. 20, showing stem of a tree fern). 



As the name of the class implies, the plants belonging to 

 it are without cotyledons or seed-leaves. Some of them are 

 even destitute of stem, branch, or leaf ; for the acotyledons 

 include the lowest forms of vegetation, down to the mildew 

 seen in stale bread, cheese, fruit, etc. Nevertheless they 

 are all, in their several ways, developed specimens of plant 

 life, no matter how mean or minute their appearance. 

 Many noble and beautiful plants belong to this class. 

 Foremost amongst them are those graceful species of 

 vegetation — the ferns. 



Ferns 1 are generally perennial {lasting year after year) 

 plants. Some kinds, natives of warm climates, grow to a 

 considerable height (often 40 or 50 feet), and are termed 

 arborescent or tree ferns. In many parts of Australasia 

 fern gullies exist, and are the favourite haunts of these 

 plants, which love shade and moisture. In such spots they 

 are found of all shapes and sizes ; from the tall tree fern, 

 expanding its crown of cool green fronds or leaves under 

 the shelter of the huge trees overshadowing them, down to 

 the tiny yet equally beautiful specimens of the tribe ; some 

 of them so small that they may be crushed underfoot 



1 With regard to the number of species in this family there is great 

 diversity of opinion. Sir William Hooker, in his Synopsis Filicum, 

 has described 2300 species ; but since the publication of that valuable 

 work many new kinds have been discovered, and the approximate 

 number may now be safely given at over 3000 distinct species, not 

 including varieties. 



