FAMILY SORANGIACEAE 1021 



FAMILY III. SORANGIACEAE JAHN. 



(Beitriige zurbotan. Protistologie. I. Die Polyangiden. Geb. Borntraeger, Leipzig, 

 1924, 73.) 



Diagnosis : The shortened rods of the fruiting body lie in angular, usually relatively 

 small cysts of definite polj'^gonal shape. Often many of these cysts are surrounded 

 by a common membrane. The primary cyst may be differentiated from the angular 

 or secondary cysts. No stalked forms are known. 



Genus I. Sorangitim John. 



(Jahn, Beitrage z. botan. Protistologie. I. Die Polyangiden. Geb. Borntraeger, 

 Leipzig, 1924, 73; Cystoecemia Enderlein, Bemerkungen z. Systematik d. Chondro- 

 myciden, Berlin, 1924, 73.) 



Etymology : Greek soros, heap and angion, vessel. 



Diagnosis : As for the family. The cysts are united into rounded fruiting bodies. 

 Eight species have been allocated to this genus. 



The type species is Sorangium schroeteri Jahn. 



Ke7j to the species of Genus Sorangium. 



I. Fruiting bodies not black when ripe. 



A. Primary cysts absent; fruiting body shows only angular, spherical or oval 



small cysts. 



1. Cysts angular. 



a. Fruiting body very small (50 to 80 microns), often irregularly cerebri- 

 form; the angular cysts often completely separated from each other, 

 and about 13 microns in diameter. 



1. Sorangium schroeteri. 

 aa. Fruiting body composed of many small cysts. 



b. Cysts orange-red in color; over 5.0 microns in diameter. 



2. Sorangium sorediatum. 



bb. Rust}' brown color; cysts less than 3.5 microns in diameter. 



3. Sorangium cellulosum. 



2. Cysts spherical or oval. 



4. Sorangium spumosum. 



B. Both primary and secondary cysts present. 



1. Primary cysts small and numerous, about 20 microns, with definite mem- 



brane and few angular secondary cysts. 



5. Sorangium septatum. 



2. Primary cysts large, with delicate, often indefinite, membrane. 



6. Sorangium compositum. 

 II. Fruiting bodies black or brownish-black when ripe. 



A. Primary cysts generally not formed. 



7. Sorangium nigrum. 



B. Primary cysts generally formed. 



8. Sorangium nigrescens. 



1. Sorangiimi schroeteri Jahn. (Jahn, I. Die Polyangiden. Geb. Borntraeger, 

 Beitrage zur botanischen Protistologie. Leipzig, 1924, 73; regarded as a synonym 



