CHAPTER X 

 DIVISION I. THALLOPHYTA: THE THALLUS PLANTS 



THIS Division of the Plant Kingdom comprises the lower 

 and simpler, which are also the more ancient and primitive, 

 kinds of plants. They are either Algae (the seaweeds and 

 their kin), making their own food photosynthetically, or 

 else Fungi (the molds and their kin), taking their food para- 

 sitically or saprophytically from other organisms. Some 

 80,000 species are known, and the group thus comprises 

 one third of all existent kinds of plants. 



The plant body in Thallophytes has most diverse forms, 

 being spherical, filamentous, filmy, or frondose ; but it never 

 exhibits that differentiation into absorbing root, food-form- 

 ing leaves, and supporting stems, so distinctive of the higher 

 groups. In size they range from microscopical, in the 

 unicellular kinds, up to gigantic, in some of the coastal 

 seaweeds, the Algae in general averaging much larger than 

 the Fungi. The Algae contain chlorophyll, with the associ- 

 ated carotin and xanthophyll (pages 89-90), and often addi- 

 tional pigments. These are usually in CHROMATOPHORES, 

 which are few, or even one, in lower forms, but are small 

 and many (the chloroplasts) in the higher kinds. The 

 Fungi lack them, and take their food in organic form through 

 haustoria or feeding mycelia, as already fully explained 

 (page 82). 



The reproduction in Thallophytes is also diverse, being 

 vegetative in various ways, or by fission, or by asexual 

 spores, or by sexual methods, which also involve spores. 



