Acaulangium bulbaceus (Graham) Millay
Plant Fossil Names Registry Number: PFN000028
Act LSID: urn:lsid:plantfossilnames.org:act:28
Authors: M. A. Millay
Basionym: Cyathotrachus bulbaceus Graham
Reference: Millay, M. A. (1977): Acaulangium gen. n., a fertile marattialean from the Upper Pennsylvanian of Illinois. – American Journal of Botany 64(2): 223–229., link
Page of description: 223
Sporangia four to six, attached basi-laterally to a short central column, their bases completely united to form a saucer-shaped receptacle. The sporangia are united laterally for the greater part of their length by a common wall, a deep cup being left at the summit of the synangium. Synangia pedicellate and bulblike in shape, measuring about 0.65 mm. in diameter. Spores are 18 μ in diameter.
The geologic horizon from which these petrifactions were obtained is about Middle Conemaugh in age, and is near the top of the Pennsylvanian strata found in Illinois.
Upper Pennsylvanien according to Millay (1977: Amer. J. Bot., 64(2): 223).
Calhoun coal mine, Richland County, Illinois