Mosses are some of the most ancient and resilient plants on Earth, having evolved over 400 million years ago. One particularly interesting genus of moss is
Oxystegus (Limpr.) Hilp., commonly known as Oxystegus moss. This small but mighty plant plays important ecological roles and has some remarkable adaptations. In this post, we’ll dive into the details of Oxystegus moss and discover what makes it so fascinating.
Background
Oxystegus moss belongs to the Pottiaceae family, which is one of the largest families of mosses with over 1,500 species worldwide. The Pottiaceae are known as “twisted mosses” due to the contorted appearance of their leaves when dry. Oxystegus was originally classified as a subgenus of Trichostomum but was later elevated to genus status.
Morphology and Identification
Oxystegus mosses form small tufts or cushions, typically under 1 cm tall. Their
leaves are lance-shaped and have a strong midrib that often extends beyond the leaf tip as a stout point called a mucro. The leaf margins are usually entire (smooth) and may be recurved (curved back). One key identifying feature of Oxystegus is its peristome, the ring of tooth-like structures surrounding the opening of the spore capsule. In Oxystegus, the peristome has 16 teeth that are often paired and twisted counterclockwise. The
spore capsules are cylindrical and borne on a seta (stalk) 1-2 cm long.
Global Distribution and Habitat
Oxystegus has a cosmopolitan distribution, meaning it is found on every continent except Antarctica. In North America, there are three species: O. tenuirostris, O. hibernicus, and O. recurvifolius. These mosses typically grow on calcareous substrates like limestone and concrete in open, disturbed habitats. They can often be found along trails, roads, and in urban areas, as well as in natural habitats like alvars, cliffs, and rock outcrops. Oxystegus is tolerant of drought and can survive long dry periods.
From its tiny twisted leaves to its globe-spanning distribution, Oxystegus is a prime example of how mosses have successfully evolved to inhabit a wide range of environments. The next time you see some small green cushions growing on rocks or sidewalks, take a closer look – it might be Oxystegus! These unassuming plants are a testament to the incredible resilience and adaptability of mosses. What other secrets of the botanical world are yet to be uncovered?
