Sack Starwort (Asterella saccata)  Fragrant Macewort (Mannia fragrans)

This post was originally published in April 2019. At the time, I identified the specimen as  Mannia fragrans based on the information I had available at the time. Recently, an Italian bryoplogist, Guido Brusa, sent an email stating the photographs in the post were for a species of  Asterella. Initially, I thought  Mannia was still the correct identification but delving deeper into the literature, it appears that this specimen is  Asterella saccata a new species that I don’t think has been reported for British Columbia. It appears to have been collected only a few times of which the closest collections appear to be in Washington State and Waterton Park in Alberta. My thanks to Guido for taking the time to help correct this post and providing additional identification and ecological information.

Paul Handford recently found and photographed an unusual plant in the grasslands and kindly gave me the location information. This is a liverwort named sack starwort (Asterella saccata). (I actually could not find a common name for this species – some people call species that belong to this genus “starwort” – I added the name “sack” because the species name “saccata” refers to a sack-like structure). Liverworts are a group of primitive plants distantly related to mosses. Some liverworts lack stems and leaves and consist of a flat thallus – similar to many foliose lichens. Notice the white pores on the surface of the thallus. These pores open into cavities packed with photosynthetic tissue. A cross-section through the thallus showing the cavity beneath the pore is shown in the second photo below.

Starwort growing just to the right of the lens cap.

Sack starwort is unusual because it grows in open grasslands around Kamloops where it would not normally be expected to survive the hot, dry conditions. It manages to survive because it completes its life cycle in a very short period of time in the spring when the soil is moist. Sack starwort begins to grow and produce spores in March and complete its lifecycle and die back for the rest of the growing season by the end of April.

Reproductive structures of macewort.

The spores are produced in small flask-shaped structures that hang in groups of 3 or 4 from elevated stalks that emerge from the surface of the thallus. These spore sacs are bright yellow at maturity and are surrounded by a white skirt-like structure that surrounds the spore sacs. This skirt and the numerous white filaments at the base of the stalk help in identifying sack starwort.