Friday, July 18, 2014

Mosses of Central Florida 7. Thuidium delicatulum

The leafy stems of  Thuidium delicatulum branch into a fern-like pattern.
The leaves are boat-shaped and packed densely
along the stem.
[For other mosses in this series, see the Table of Contents]

Thuidium delicatulum (Hedw.) Schimp. (Thuidiaceae) is easy to recognize due to its strikingly fern-like appearance.  Its leafy structure of course is not a true compound frond as in actual ferns, but a finely branched stem system with tiny leaves.

The small leaves have a weakly-developed midrib (costa).
The leaves are roughened with tiny tooth-like papillae.

The leaves are small with a weakly-developed midrib, and roundish to oval cells that each have strongly developed papillae (small clear bumps).  Branched filaments, called paraphyllia, are also present among the leaves. Sporangia are uncommon, but described as "elongate, asymmetric, and inclined" (Reese, 1984, Mosses of the Gulf South).

Slender, sometimes
branched paraphyllia
are found among the leaves.

Thuidium delicatulum is distributed widely in northern and eastern North America, as well as South America. It extends westward from Florida into Texas.  Another species in Central Florida is T. allenii, which has a similar branching structure, but less regular and more straggly, not quite giving the appearance of a fern.  The papillae are also smaller.  T. minutulum is found further north, and also in Highlands County, and has mostly simple, unbranched stems, and short, unbranched paraphyllia.  T. pygmaeum is similar, and has been found only in Jackson County.

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