THE AMERICAN BOTANIST 61 



composed of both an algae and a fungus living together sym- 

 biotically, or more or less dependent on each other for exist- 

 ence. Fungi are never green, but "Indian Pipe" and a few 

 other seed plants resemble them in this way {Monotropa and 

 Ptcrospora, Order 57; Bpiplicgus and Orobanche, Order 62) ; 

 also a few algae. 



A system of botany to be useful, must be made so that 

 strange plants can be located in it so as to enable one to learn 

 what is already known about their usefulness for food or 

 otherwise. To find where a plant belongs in this Outline of 

 the \^egetable Kingdom, it is necessary to read the definition 

 given for each Division, class, etc., remembering that it may 

 be difficult, especially for a beginner to identify some plants 

 without knowing more or less of their life-history. 



Division 1. — Mushrooms are not composed of the same 

 materials that sea-weeds are composed of, but by comparing 

 the two kinds of plants, it becomes clear what is meant by 

 saying that each plant of Division 1 is composed of the same 

 materials throughout, while a plant having the leaves, flowers, 

 seeds, etc., composed of different materials, must be looked for 

 in one of the other three divisions. 



Division 2. — The flozvers of all plants of Sub-Kingdom 

 2, may be called the Sexual Generation; all other stages of 

 the growth of these plants constitute the Asexual Generation. 

 In the plants of Division 2, the generation that corresponds 

 to the flowers of Divisions 3 and 4, grows entirely differently. 

 In Mosses (Order 18) the whole familiar plant is the sexual 

 generation, while the little stalks and spore capsules (called 

 sporogonia) that grow parasitically on the green plants, be- 

 long to the asexual generation — exactly the opposite of 

 Phaner ogams (Sub-Kingdom 2). 



The sexual generation of Orders 19, 20, and 21, called 

 prothaUus or pro thallium insted of flower, starts its growth 



