Etym.: the name refers to the caespitose nature of its growth.
Spore-sac large, up to 20 mm diem, globose to globose-deformed. Exoperidium indistinct, but not conspicuously membranous, although at times it might seem so; apparently very thinly membranous and persistent. Endoperidium finally subsmooth to rough to touch, chamois-cinnamon coloured to Ridgway's "Clay colour". Mouth circular, planè, hardly at all projecting but in many peridia elliptic or distorted, or more than one present. Socket deep, separated, generally covered by clay, membrane lacerated. Gleba light ferrugineous. Stem normally around 20 x 4 mm, but in many specimens it is distorted and may be much larger, concolorous with the endoperidium, rugose-fibrous, caespitose. Sometimes more than one fused in a single specimen.
Spores minutely asperulate, guttulate, globose to elliptic, subhyaline, episporium relatively thick and ornamentation uneven under L.M.; under SEM the verrucae appear dispersed, lbw and blunt; 4.2-5.9 µm diam. Capillitium subhyaline to yellowish, much branched, septate, with thick-walled threads and lumen visible or solid or very wavy to lacunar, sometimes the whole thread wavy; septa infrequent, disjointable; 4.2-5.9 µm diam. Habitat: sandy soil in desertic areas.
Distribution: AFRICA: Algiers, Tunisia. North America: United States (New Mexico). South America: Argentina. ASIA: U.S.S.R.: Kazhastan.
Holotype: I am not satisfied with the fact that none of the specimens examined qualifies as a real holotype of this species. It is very likely that a material in Bresadola's herbarium at S could be part of the original collection by Trabut. Otherwise one could select as neotype "T. caespitosum var. acaule" from Algiers, leg. Trabut, X.1898 in Patouillard's herbarium (FH) which agrees with the protologue.