Tuesday, January 9, 2018

Mosses of Central Florida 41. Tortella

The genus Tortella (Pottiaceae) includes two species found in Florida.  The genus is distinguished from other members of the family, such as Barbula or Hyophiladelphus by the distinctive V- or U-shaped boundary between the large basal region of clear cells and the upper green cells.  It shares with them the elongate leaves with strong midrib, and the upright spore capsules with long twisted teeth around the opening.  Leaf cells in the upper part of the leaf are small, round and papillose.
Leaves of Tortella densa illustrate the distinctive leaves of the genus.  Note the V-shaped boundary between the large clear cells at the base and the smaller green cells of the tip.  Photo by Hermann Schachner, posted on Wikimedia, Creative Commons license.
The long, twisted teeth around the opening
of the spore capsule, characteristic of
Tortella and several other genera of the
Pottiaceae.  Photo courtesy the Western
New Mexico University, Department of
Natural Sciences and the Dale A.
Zimmerman Herbarium,
Plants of the Gila Wilderness.

Tortella flavovirens (Bruch) Brotherus and T. humilis Hedwig both form low colonies of upright leafy shoots, with leaves distributed uniformly around the stem (radially symmetrical).  Capsules arise from the tips of the shoots. In T. humilis the stems are  elongate, forming loose tufts, while in T. flavovirens, they are more compact, forming dense mats of rosettes.

In Florida, both species occur scattered throughout the state. Tortella humilis is found throughout eastern North America and in scattered mountain locations from New Mexico to British Columbia. It is found inland on soil, tree bases, and rocks. T. flavovirens has a more southern distribution, from Texas to North Carolina. It is tolerant of salt spray and is confined to coastal vegetation.


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