PlantaeDB Logo
Login Sign-up

Genus Trichostomum in Family Pottiaceae

In botanical taxonomy, a genus (plural genera) is a rank used to group closely related species within a family. In the hierarchy, genus sits below family and above species.

Genera are defined by shared morphological, anatomical, and genetic characteristics (for example, features of flowers, fruits, seeds, or leaves) that indicate a close evolutionary relationship among the species they contain.

Each genus can include one or more species. Examples include Rosa (roses) and Solanum (nightshades, including tomato and eggplant).

Do you wish to read more about plant taxonomy? Click here!

Genus Description

Suggest a correction!

Trichostomum is a moss genus in the family Pottiaceae (order Pottiales). About 30 to 40 species are presently accepted, with the highest concentrations in Europe, East Asia, and western North America, and elsewhere (World Flora Online, 2024). The type species most often cited is Trichostomum brachydontium (Hedw.) Bruch, though some treatments refer to T. viridulum as typifying (Crum & Anderson, 1981). Plants form compact cushions on calcareous rock, mortar, or limestone outcrops in open, well‑lit sites.

Morphologically the genus is acrocarpous; stems are erect, sparingly branched, and bear linear‑lanceolate leaves that are keeled and terminate in a short hyaline hair‑point. Leaves are usually entire‑margined, occasionally slightly revolute, and lack stipules. The lamina is unistratose and the leaf base is slightly concave. Sexual reproduction follows the typical Pottiaceae pattern: male and female gametangia occur on separate or on the same plants, producing a short seta, an erect cylindrical to ellipsoidal capsule, and a mitrate to cucullate calyptra. Peristome teeth are highly variable; many taxa possess a reduced, irregular peristome or lack one entirely (Zander, 1993).

Diversity is greatest in Europe and the mountain ranges of China, where several narrow endemics occupy limestone cliffs above 2000 m (Gradstein & Sollman, 2015). The genus occupies exposed rock faces, old walls, soil in open woodland clearings, and occasionally disturbed sites, tolerating high light and relatively low moisture. Recent nuclear and chloroplast phylogenies (Liu et al., 2020) have shown that the traditional broad concept of Trichostomum comprises several clades now assigned to Didymodon and Syntrichia. Consequently, many former Trichostomum species have been transferred (e.g., T. caespiticium → Didymodon caespiticium), leaving a core clade of roughly 15 species. Alternative treatments maintain a wider circumscription, but the molecular evidence supports the narrower, phylogenetically defined concept.

Human relevance is modest. Some species are collected for terrarium hobbyists and serve as indicator organisms for calcareous substrate quality, but the genus lacks commercial timber or agricultural value.

Conservation concerns centre on habitat loss from urbanization, quarrying, and climate‑induced drying of rock outcrops; population data remain incomplete for several narrow endemics. Focused field surveys and ex‑situ cultivation are needed to safeguard the remaining diversity.

Pick a Species to see its components: