BLASTOCLADIALES 659 



BLASTOCLADIACEAE 



Thallus walled, highly variable in extent, usually with a basal cell 

 anchored to the substratum by branched rhizoids, nonseptate or pseudo- 

 septate, sometimes with sterile setae, of determinate or indeterminate 

 growth; reproductive rudiments one or more, sessile or variously borne 

 on the basal cell or its branches or on hyphae, delimited from the thallus 

 by true cross walls at maturity; sometimes differentiated into similar 

 sporophyte and gametophyte phases; zoospores borne in thin-walled 

 sporangia, emerging through one or more pores; resting spores punc- 

 tate; smooth-walled or variously ornamented, in a thin-walled contain- 

 er, upon germination producing planonts; sexuality isogamous, anisog- 

 amous, or lacking; plants monoecious or (in Blastocladiella) dioecious; 

 life history of the Euallomyces, Cystogenes, or Brachyallomyces type. 



Saprophytes in water and soil on a variety of plant and animal debris. 



KEY TO THE GENERA OF THE BLASTOCLADIACEAE 1 



Thallus consisting of a single reproductive rudiment from which the 

 rhizoids emerge directly, or of a reproductive rudiment borne at 

 the apex of an unbranched basal cell anchored by rhizoids to the 



substratum Blastocladiella, p. 660 



Thallus bearing an indeterminate number of reproductive rudiments 



on the basal cell or on its branches 



Thallus consisting of a basal cell and a few depauperate, distal, 



dichotomously branched hyphae, without pseudoseptae, one of 



the dichotomies usually rudimentary; resting spore loose 



within its container, unpitted Blastocladiopsis, p. 668 



Thallus consisting either of a basal cell from which arise strongly 



developed dichotomously branched, pseudoseptate hyphae which 



bear the reproductive rudiments, or of a basal cell alone, the 



reproductive rudiments sessile or on lobes or extensions of the 



basal cell 



Thallus with an unlobed or unbranched basal cell which gives rise 



distally and usually dichotomously to cylindrical pseudoseptate 



branches, setae never formed; zoosporangium with one or 



more discharge papillae ; gametophytes known . . Allomyces, p. 669 



1 Sorgel (1952) gave fragmentary accounts of certain soil fungi which he assigned 

 to this family as new genera, viz., Ramocladia, Allocladia, Brevicladia, and Leptocladia. 

 It is hoped that more complete descriptions will be forthcoming, so that these forms 

 may be properly evaluated. 



