22O MORPHOLOGY. 



like an earth star (Sclerogaster), or portions of the surface become gelatin- 

 ized (Phallogaster). The last-named one grows on very rotten wood, while 

 most of the others grow on the ground. 



470. Order Lycoperdales (Lycoperdineae). These include the "puff- 

 balls," or "devil's snuff-box" (Lycoperdon), and the earth stars (Geaster). 

 The basidia form a distinct hymenium, but at maturity the entire inner por- 

 tion of the plant (except certain peculiar threads, the capillitium) disinte- 

 grates and with the spores forms a powdery mass. 



471. Order Nidulariales (Nidulariineae). These are known as bird-nest 

 fungi. The fruit body when mature is cup-shaped, or goblet-shaped, and 

 contains minute flattened circular bodies (peridiola) containing the spores. 

 The intermediate portions of the fruit body disintegrate and set the peri- 

 diola free, which then lie in the cup-shaped base like eggs in a nest. 



472. Order Plectobasidiales (Plectobasidiineae). The basidia do not 

 form a definite hymenium, but are interwoven with the threads inside, or 

 are collected into knot-like groups. (Examples: Calostoma, Tulostoma, 

 Astraeus, Sphaerobolus, etc.) 



472a. Lichens. The plant body of the lichens (see paragraphs 200, 

 201) consists of two component parts, the one a fungus, the other an alga. 

 The fructification is that of the fungus. The fruit body shows the lichens 

 to be related some to the Ascomycetes, others to. the Hymenomycetes, and 

 Gasteromycetes. They are usually classified as a distinct class or order 

 from the fungi, but a natural arrangement would distribute them in sev- 

 eral of the orders above. Their special relationship with these orders has 

 not been satisfactorily worked out. For the present they are arranged as 

 follows: 

 Ascolichenes. 



Pyrenocarpous lichens (those with a fruit body like the Pyrenomycetes). 



Gymnocarpous lichens (those with a fruit body like the Discomycetes). 

 Hymenolichen.es (those with a fruit body like the Hymenomycetes). 

 Gasterolichenes (those with a fruit body like the Gasteromycetes). 



From a vegetative standpoint there are two types according to the dis- 

 tribution of the elements. 



i st. Where the fungal and algal elements are evenly distributed in the 

 plant body the lichen is said to be homoiomerous. There are two types of 

 these: 



a. Filamentous lichens, example, Ephebe pubescens. 



b. Gelatinous lichens, example, Collema (with the alga nostoc), Physma 

 (with the Chroococcaceae). 



2d. Where the elements are stratified, as in Parmelia, etc., the lichen is 

 said to be heteromerous. In these there are three types: 



a. Crustaceous lichens, the plant body is in the form of a thin incrusta 

 tion on rocks, etc. 



