BLASTOCLADIALES 683 



Basal cell distinctly clavate, the branches, when formed, always 

 clavate 



Sporangia not proliferating B. pringsheimii, p. 684 



B. aspergilloides, p. 686 



Sporangia proliferating B. sparrowii, p. 686 



Basal cell globose the cylindrical part very short or absent 



B. globosa, p. 687 

 Basal cell cylindrical throughout only slightly, if at all, clavate, 

 branched or unbranched 



Sporangia proliferating B. prolifera, p. 688 



Sporangia not proliferating 



Sporangia about nine times as long as wide; borne on short 



branches of the basal cell B. angusta, p. 688 



Sporangia about from three to four times as long as wide; 

 arranged subracemosely, corymbosely, cymosely, or 

 subdichotomously on short branches 

 Sporangia cylindrical to broad-clavate .... B. incrassata, p. 689 



Sporangia long-cylindrical B, gracilis, p. 690 



Sporangia predominantly narrowly or broadly ovoid, fusiform, beaked, 

 or broadly ellipsoidal or dome-shaped and truncate 

 Sporangia narrowly or broadly ovoid or fusiform, appearing beaked ; 

 thallus cylindrical throughout 

 Walls of the thallus smooth 



Sporangia and the thick-walled brown resting spores appearing 



beaked B. rostrata, p. 690 



Sporangia beaked; resting spores with rounded apex, thin- 

 walled, colorless B. ramosa, p. 691 



Explanation of Figure 47 



A. Blastocladia gracilis Kanouse, habit of plant bearing racemosely arranged 

 empty zoosporangia. B. Blastocladia tenuis Kanouse, plant showing sculptured 

 wall. C-D. Blastocladia ramosa Thaxter : C, habit of plant ; D, optical sections 

 of two resting spores from type material, showing canals of pits in outer walls. 

 E. Blastocladia angusta Lund, habit of upper part of plant. F. Blastocladia 

 incrassata Indoh, habit of plant. G-J. Blastocladiopsis parva (Whiffen) Sparrow : 

 G, terminus of a dichotomy showing two smooth-walled resting spores lying 

 loosely in their containers; H, resting spore producing zoospores upon 

 germination ; /, thallus bearing two resting spores and two empty zoosporangia 

 each with two discharge pores; /, dwarf plant consisting of a few rhizoids in 

 substratum and short basal cell and single resting spore. 



(A, Kanouse, 1927; B, after Kanouse, 1927; C, after Thaxter, 1896a: £, 

 Lund, 1934; F, Indoh, 1940; G, after Sparrow, 1950; H, Whiffen, 1943; I-J, 

 Sparrow, 1950) 



