MUCORACEAE 83 



families differ with the different authors. All agree on using the 

 distinction between asexual reproduction by sporangiospores or by 

 conidia (sporangiola) as an important point in subdividing the order. 

 The following key derived from Zycha gives the characteristics of 

 the families. 



FAMILIES OF MUCORALES 



A. Sporangia single, multispored sporangia always with columellae. 



1. All sporangia multispored. MUCORACEAE 



2. Sporangiospores with two kinds of spore-forming apparatus, terminal multi- 

 celled sporangia, and numerous lateral verticillate sporangiola, each with few 

 spores. THAMNIDIACEAE 



B. Sporangiola or conidia united on special sporophores. 



3. Spherical, single, or many-spored sporangiola on specialized enlargements of 

 the fruiting hyphae. CHAENOPHORACEAE 



4. Long chains of small sporangiola usually on specialized basal cells. IMostly 

 parasitic on Mucorales. CEPHALIDACEAE 



C. AU sporangia without columellae, zygotes surrounded by thick covering of 

 hyphae. 



5. Sporangia or zygotes single. MORTIERELLACEAE 



6. Sporangia or zygotes united in specialized fruiting bodies surrounded by 

 hyphae. ENDOGONACEAE 



Mucoraceae. The Mucoraceae are a group of molds, frequently 

 referred to as the bread molds, found abundantly in soil, in manure, 

 on fruits, and especially on starchy foodstuffs. They all have the 

 same general structure and appearance and are easily differentiated 

 from other groups of molds by the coarse, non-septate mycelium, by 

 the abundant and loosely meshed aerial mycelium, and by the lack 

 of distinctive colors, the spores being generally black or brown, the 

 mycelium white or gray. In older literature the term mold is fre- 

 quently restricted to fungi of this type, molds of the type of the 

 Fungi Imperfecti being referred to as mildews. 



The Mucoraceae and Thammidaceae are distinguished from the 

 other families of the order by the presence of a columella in the 

 sporangium. The columella may be looked upon as a septum sepa- 

 rating the sporangium from the sporangiophore, which has become 

 bulged into the sporangium. In addition to sporangiospores some 

 species also reproduce by chlamydospores which appear as round 

 black swellings, like beads, strung on the mycelium. These may be 

 mistaken for zygospores. Several species also characteristically 

 break up into a series of spherical oidia when immersed in liquid 

 where aeration is not abundant. These oidia, yeast-like in appear-' 

 ance, may reproduce for a while by budding, forming new round cells 

 of the same type. Sporangiola are not formed by the Mucoraceae. 



