PHYSARUM 47 



IL Fructification of sporangia more or less distinct. 



A. Sporangia sessile, globose, ovoid, reniform, etc. 



1. Peridium double. 



a. Sporangia white, peridium testaceous . 8. P. diderma 



b. Sporangia tinged with yellow. 



i. Sporangia as if interwoven, compressed 



9. P. contextum 

 ii. Sporangia more nearly free, distinct. 



* Spores pale, inner peridium brittle 



10. P. conglomeratum 

 ** Spores spinulose, dark violet 11. P. mortoni 



c. Sporangia brown, dehiscence revolute 12. P. brunneolum 



2. Peridium simple, calcareous, flaky. 



a. Sporangia grey, plasmodiocarpous; spores dusky, 10-12 



forms of 3 



b. Sporangia grey, more or less dense; spores violet, 6-7 



13. P. cinereum 



c. Calcareous deposits yellow or greenish, spores 7-9 



14. P. vires cens 



d. Sporangia rusty or reddish brown, more or less dense 



15. P. rubiginosum 



e. Sporangia minute, lignicolous, the fructification much ex- 

 tended upon a hypothallus, lime deposit tawny 



16. P. instratum 



f. Sporangia white, depressed, annulate, sometimes with 

 short stipes . , . . 17. P. megalosporum 



3. Peridium simple, not flaky, small .2-3 mm., heaped 



18. P. confertum 



B. Sporangia, at least some of them, stipitate. 



a. Sporangia columellate. 



i. Columella small, usually conical. 

 * Sporangium yellow. 



Columella white . . 19. P. melleum 

 Columella yellow . . 20. P. citrinum 

 ** Sporangium not yellow. 



Capillitial mass persistent. 



t Sporangia globose, pallid or white 



21. P. globuliferum 

 tt Sporangia blue or lilac, rose, etc. 



22. P. idacinum 

 ttt Sporangia drab or brownish 



23. P. murinum 

 tttt Sporangia wine-red 24. P. pulcherrinum 



Capillitial-mass less persistent; orange 



25. P. pulcherripes 

 ii. Columella long, 4-5 the sporangium non-calcareous. 



26. P. peneirale 

 iii. Columella large globose . . 27. P. luteo-album 



