138 SYSTEMATIC BOTANY. 



non-sexual reproduction is by means of tetraspores. The 

 carpogonium is peculiar in having a long filamentous 

 appendage (trichogyne) to which the spermatozoids attach 

 themselves when set free from the antheridium. Fertiliza- 

 tion takes place in consequence of this contact, and the 

 result is the production of the sporocarp. This, in some 

 species, is very simple, and consists of the spores and the 

 short branches which bear them; ia others the mass is 

 surrounded by a covering, or pericarp, developed from 

 peripheral cells of the carpogonium. Some orders of the 

 Floridese contain " species which display the most exquisite 

 combination of ramification and coloring." The " Dulse" 

 {Ehodymenia palmata) is used as human food. The Irish 

 Moss {Chondrus crispus) is extensively used also for food. 



172. An exceedingly large and important group of the 

 Carposporese is the so-called Ascomycetes. The plants 

 are all destitute of chlorophyll, but difier among them- 

 selves to great extent as to size and appearance. They are 

 all alike, however, in producing their spores in sacs, called 

 asci ; the spores are, therefore, called ascospores. The 

 following are the most important orders : 



I. Erysiphaceae, The plants of this order are mainly 

 parasitic, and consist of a mass of branching, jointed fila- 

 ments, which form a white web-like film on the surface of 

 the leaves and stems on which they grow and from which 

 they draw their nourishment. They are very abundant, 

 and often do great injury to the Apple, Cherry, Grape, 

 Pea, etc. The conidial spores are produced in great 

 abundance during the summer. Later, the sexual repro- 

 duction takes place in the manner described in paragraph 

 170 (Fig. 251). The sporocarp, or perithecium, has at its 

 base radiating filaments, or appendages (ambulacra) ; they 



