Thursday, April 23, 2015

Mosses of Central Florida 13. Philonotis longiseta

Philonotis longiseta clings to rocks along the edges of babbling
brooks. Specimen preserved as Essig 20150402-1 (USF).
[For other mosses in this series, see the Table of Contents]

Philonotis longiseta (Michx.) E. Britton  (Bartramiaceae) is a moss of wet places.  It is most often found on rocks or banks of streams, where it is constantly splashed and misted by rapidly moving water. It was said by Reese (1984) that it rarely forms sporophytes in the coastal Gulf of Mexico region, but I recently found it beside the artificial stream at the USF Botanical Garden in Tampa with abundant ripe spore capsules.  What exactly about this spot favors reproduction is not clear. Perhaps, the species requires a very stable situation, without drying or submergence, and such conditions are rare along Florida waterways.  In the constantly flowing artificial stream, however, the plants are continuously misted.

The midrib, or costa, extends as a sharp tip at the end of the leaf.  Cells are
rectangular and more elongate in the central part of the leaf. 
The leafy shoots are upright, forming bright green spongy masses clinging to the vertical rock surfaces. Leaves are stiff, long-triangular and have a prominent midrib that extends as a point beyond the tip of the leaf.  Leaf cells are elongate-rectangular, with usually a small papilla (hard, clear bump) at the upper end of each cell.

The spore capsules are frequently surrounded by
drops of water that form from the continuous
The most distinctive feature of the genus, and others in the family that are not found in Florida, are the very round spore capsules, causing them to be generally known as apple mosses.  They form at the ends of long stalks rising from the bases of the leafy shoots.

Several other species of Philonotis have been reported from Florida, but are rare, and differ in minor ways.  P. longiseta occurs throughout eastern North America, the West Indies, Central and South America.

Reese, W. D. 1984. Mosses of the Gulf South: From the Rio Grande to the Apalachicola. Louisiana State University Press.

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