The apical thickening is sometimes less dense in the inner part of the spore. In some specimens this appears to be a secondary development. In the Nevada study area the species is found in the Ludlow and late Wenlock of the Laketown Formation and Roberts Mountains Formation, and the Ludlow of the Sevy Formation. It is most common in portions of the Ludfordian through the Homerian, of the Upper Silurian. Calamospora witneyana is much larger and usually over 110 in diameter, with a mean width of 165 .
Spores belong to the plant kingdom.
Most palynologists agree that these forms represent ancient fruiting body elements of plants long extinct. This species of spore pictured was first formally described by Streel in 1967.