ORDER MUCORALES 



169 



is more like the Piloholus type except that the zygospore buds out from 

 the united gametangia and matures externally. (Fig. 55.) 



Family Kickxellaceae. Linder (1943) erected this family to contain 

 Kickxella, Coemansia, and Martensella. In these the sporangia (conidia) 

 are indehiscent and one-celled, but in the first-named genus an incom- 

 plete septum indicates that perhaps it is descended from a two-spored 

 ancestral form. In all three genera there are special lateral sporangium- 



FiG. 58. Mucorale^ 

 Family Mortierellaceae. 

 Dissophora decunibens 

 Thaxt. (A) Young apical 

 portion of fertile hypha. 

 (B) Portion of fertile 

 hyphae bearing sporangi- 

 ophores. (C) Mature spo- 

 rangium. (After Thaxter: 

 Botan. Gaz., 58(4): 353- 

 366, Univ. of Chicago 

 Press.) 



bearing sporocladia consisting of several cells. From each cell of these 

 except one or more terminal cells arise several sterigmata each bearing a 

 single conidium. The sporocladium with its conidia somewhat resembles 

 a comb. The nearest relationship of this family appears to be with some 

 members of the preceding family. Sexual reproduction has been observed 

 in only one species of Coemansia and resembles considerably that of 

 Piloholus. (Fig. 56.) 



Family Mortierellaceae. The position of this family is uncertain. 

 In sporangial structure the absence of a columella would indicate a posi- 



