Tetraphis geniculata generally occurs on decaying logs or stumps from sea level to subalpine elevations. Sometimes it can grow on peaty soils in a moist environment and rarely on rocks.
This small species typically forms tufts that are green to reddish-brown.
The ovate-shaped leaves measure 1-2 mm and have a pointed tip. Furthermore, they become slightly contorted when they are dry. A costa is present and ends below the apex of the leaf.
The sporophytes of T. geniculata are rare, but when they do occur they tend to mature in the spring or early summer.
The sporangium is narrow, cylindrical, and yellow-brown in color. The genus name refers to the four peristome teeth, which are present in this species.
The seta is geniculate (has an abrupt bend) near the middle. Above the bend, the seta has papillae, whereas below the bend, cells are smooth. Furthermore, the long seta becomes twisted when dry. These are important characteristic when trying to identify this species because the gametophytic characteristics are identical to those of Tetraphis pellucida.