Xerophytic Features of Moss Flora.

Goebel (1905, pp. 143–149) enumerates the commoner adaptations in mosses for the retention and use of water. Mosses living perpetually in hygrophytic and often in mesophytic conditions usually have leaves of one cell thickness, and devoid of surface papillae or terminal aristae, structures common in mosses subject to periodic intervals of drought. The following features are all associated with the need for countering xerophytic conditions: (1) formation of compact cushion growth, (2) felted stems, (3) diaphanous hair-tips, (4) plication or undulation of the leaf-surface, (5) lamellation of the nerve, (6) incrassate cell structure, (7) incurving or recurving of the leaf-margin, (8) twisting, incurving, or enrolling of the leaves, (9) appression of the leaves against the stem, (10) thickening of the leaves for water-storage.