Friday, April 10, 2015

Mosses of Central Florida 12. Forsstroemia trichomitria

Forsstroemia trichomitria forms a shaggy mat on the
trunk of a Liquidambar tree along the Hillsborough River
in west-central Florida. Photograph by Alan Franck.
[For other mosses in this series, see the Table of Contents]

Forsstroemia trichomitria (Hedw.) Lindb. (Cryphaeaceae) is an epiphytic moss that forms luxurious mats on hardwood trunks in moist forests.  It is found throughout eastern Asia as well as eastern North America and northeastern Mexico.  It is in the same family as Cryphaea glomerata, recently featured here, and has a very similar habit.  I am grateful to my colleague, Alan Franck, for the new collection and photographs of this species in the field. Alan was recently appointed curator of the USF Herbarium, and shares my interest in mosses and other "cryptogams."

The orange capsules are conspicuous among the upturned
leafy shoots. Photograph by Alan Franck.
The leafy shoots spread out from the trunk and curve upward slightly.  The leaves are ovate to long triangular, and are said to usually have a midrib.  In this specimen, the midrib is weak and disappears in mid-leaf.  The cells of the leaf are elongate and curved, but not as long as in Isopterygium and its relatives, with thick clear walls between them.  The leaf cells of Cryphaea are short and roundish.
The ovate-triangular leaf of Forsstroemia trichomitria has distinctive folds
along both edges.  A weak midrib can be seen
toward the torn bottom of the leaf. From Franck 3785 (USF).

The cells in the central and upper part of the leaf are
elongate, tapered, and slightly curved, with conspicuous
clear cell walls between them.
In both Cryphaea and Forsstroemia the stalks of the spore capsules are short, presumably due to their epiphytic habit.  They are elevated on the trunks and branches of trees, and so only need to drop their spores to get them into the air.  Mosses that live on the ground need long stalks to get their spores into a good launching position.  The stalks of Forsstroemia are a somewhat elongate and their capsules are fully exposed, while  those of Cryphea remain hidden within a nest of bracts.

The orange capsules are pushed out a short distance from the leafy shoots.
A ring of yellow teeth around the capsule mouth serves to push spores out 
as it alternately moistens and dries out.  
Photo from the dried specimen (Franck 3785, USF)

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