60 BOTANY. 



The plants of tins order are remarkable as esculents, as poisonous sub- 

 stances, and as causing great injury to animal and vegetable tissues. It 

 is among these that "we find the various mushrooms, some known as furnish- 

 ing an excellent article of food, others as highly poisonous. It is difficult 

 to indicate any good character by which to distinguish the former from 

 the latter, other than that they generally grow solitary in dry pastures, 

 are rarely high colored, generally white or brownish, seldom show scales, and 

 have brittle flesh. The various moulds which occur on animal or vege- 

 table substances belong to this order. Some fungi are produced on living 

 animals. 



i^uh-order 1. Phyconiycetes : Thallus floccose, spores surrounded by a 

 vesicular veil, or sporangium. The principal genera are Phycomyces and 

 Mucor. 



Suh-order 2. Ascomycetes : Sporidia (spores), contained often in sets of 

 eight in asci or tubes. This sub-order includes the Truffle, Tuber cibarium 

 {pi. 54,ßg. 18). 



^uh~order 3. Hyphomycetes : Thallus floccose, spores naked, often septate. 



^nh-order 4. Coiiiomycetes : Flocci of the fruit obsolete or mere peduncles, 

 spores single, often partitioned, and on more or less distinct sporophores. 

 The principal genera in this sub-order are Ustilago and Uredo, the latter 

 causing the well-known smut and brand. PI. 54, fig. 16, Ustilago segetum ; 

 fig. 17, Uredo phaseoli. 



^uh-order 5. Gasteromycetes : Hymenium inclosed in a membrane (peri- 

 dium), spores as in the next sub-order. A species of Bovista one of the 

 principal genera. B. gigantea (/>/. 54, fig. 19) is remarkable for its great 

 size and for the rapidity of its growth ; having been known to increase in a 

 single night from the size of a pea to that of a melon. PI. 54, fig. 20, repre- 

 sents Morchella esculenta, an edible fungus which is prepared in large 

 quantities in some parts of Europe, by cutting into pieces and drying in 

 ovens. 



Sub-order 6. Hymeuomycetes : Hymenium naked, spores in sets of four, 

 and borne on distinct sporophores. Hydnum auriscalpium and squamatum 

 {pi. 54, fig. 23). Polyporus perennis {pi. 54, fig. 21). A species of 

 Polyporus, P.. destructor, is one of those Fvmgi which cause the dry rot. 

 Boletus umbellatus {pi. 54,. fig. 22'); B. edulis {fig. 22'); Cantharellus 

 cibarius {fig. 24) ; Agaricus fimetarius {fig. 25) ; A. campestris and squar- 

 rosus {fig. 26) ; A. procerus {fig. 27) ; and A. muscarius {fig. 28). The 

 genus Agaricus contains a great number of species, and includes some that 

 are highly poisonous, as well as others that are perfectly harmless. The com- 

 mon mushroom belongs here. 



Order 3. Lichenes, the Lichen Family. Plants forming a thallus, which 

 is either foliaceous, crustaceous, or pulverulent, these different forms de- 

 pending on the mode in which the cells are developed and combined. The 

 reproductive organs appear on the frond in the form of protuberances of 

 various kinds, consisting of an outer layer of thick-walled roundish cells, 

 more dense than the tissue of the thallus, and of a different color ; and 

 of an internal medullary layer of paraphyses and sporangia, lying 

 60 



