CELLULAR AND VASCULAR PLANTS. 73 



apparatus no longer forms a part of the general tissue, nor is im- 

 bedded in it, but special and altogether distinct organs are assigned 

 to this office. 



106. ThallophylS and Coroiophytes, It is convenient to mention 

 here, that these plants of the lower grades, Algae, Fungi, and 

 Lichens, which exhibit no proper distinction of stem and foliage, 

 are by some botanists collectively called THALLOPHYTES, that is 

 plants formed of a thai 1 us (103), or bed, as the compound word 

 imports. And the name is appropriate for the greater part of these 

 rootless, stemless, and leafless forms of vegetation, which compose 

 flat crusts or plates, like the common Lichens on rocks, walls, and 

 bark ; or spreading Mushrooms ; or the broad membranous Sea- 

 weeds, such as the Dulse and Laver : and even the plants of single 

 cells or single rows of cells are more commonly aggregated so as 

 to make up a stratum, or bed of interlaced threads, more or less 

 compact or definite. Such general names are seldom character- 

 istic of every form they are meant to comprise. The contradistin- 

 guishing name of CORMOPHYTES (meaning stem-growing plants) 

 is given to the higher forms of vegetation, from Mosses upwards, 

 because they develope a proper stem, usually adorned with distinct 

 foliage. 



107. Cellular and Vascular Plants, While the Mosses emulate 

 ordinary herbs and trees in vegetation and external appearance, 

 they agree with the lower plants in the simplicity of their internal 

 structure. They are entirely composed of cellular tissue strictly 

 so called, chiefly in the form of parenchyma (51), at least they 

 have no vessels or ducts* (57) and form no wood. They, with all 

 the plants below them, were therefore denominated CELLULAR 

 PLANTS by De Candolle. Those above, inasmuch as vascular and 

 woody tissues enter into their composition, when they are herbs as 

 well as when they form shrubs or trees, he distinguished by the 

 general name of VASCULAR PLANTS. 



108. The strength which these tissues impart owing to their 

 toughness and the close bundles or masses they form running 

 lengthwise through the stem (53, 56) enables these vascular 

 and woody plants to attain a great size and height ; while Mosses 

 and all other Cellular plants are of humble size, except when they 



*The spirally marked tubes which are found in the spore-cases of Liver- 

 worts (Fig. 85, a) offer an exception. 



7 



