Hostinella is a form genus

Form classification

Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships...

, used for bare dichotomously branching stems (axes) which have not been found in association with spore

Spore

In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

-forming organs or sporangia

Sporangium

A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...

 and so cannot be assigned to a more precise genus or species. Specimens assigned to this genus have been found in Bathurst Island, Canada, in beds of Upper Silurian age (around ), where the stems are approximately 1.2 mm in diameter; and in Lower Devonian Senni beds (from around ) where the axes have a straited external appearance and contain xylem with tracheids (diameter: 40 µm).

It is known to co-occur with Krithodeophyton

Krithodeophyton

Krithodeophyton is a genus of lower Devonian "plant" with branching axes....

.