Fissidens limbatus

This species, like the rest of the Fissidens genus, is identified by its leaves that are arranged in two rows along the stem and are half-clinging the stem and the rear leaf towards the stem tip. The leaves are unique among other mosses as it has leaves with pocket-like flaps (common name Pocket Moss). The size of the gametophyte is a few millimetres long (measured as the length of the shoot). Sterile stems are often longer than fertile shoots, and plants from caves can produce long shoots with many leaf pairs. Most of the time, the lamina in F.limbatus is unistratose; however, it is partially bistratose occasionally.

Each leaf is usually divided into three different parts:

1. The vaginant laminae (or lamina vera) is a boat-shaped or sheathing part of the leaf. The central cells of vaginant lamina somewhat more regularly arranged than ventral and dorsal laminae. The cells in this section are a little longer than wide, up to 12 micrometres wide.
2. The ventral lamina (or the apical lamina): the part of the leaf apical to the vaginant laminae on the upper side of the costa. The central cells of apical and dorsal laminae are unistratose and smooth, up to 12 micrometres wide, hexagonal-rhomboidal shaped with thin walls and no marginal thickenings.
3. The dorsal lamina is the section of the leaf edge opposite the sheathing part and the ventral lamina, extending the total length of the leaf on the backside of the costa. Dorsal lamina is not decurrent, mostly decreased to extinction at the leaf base.

Leaf pocket

Another critical characteristic of the Fissidens limbatus leaf is the leaf margin, which is formed by a border called the limbidium: long, narrow, incrassate cells. These cells in F,limbatus are unistratose to bistratose. Furthermore, sometimes, the limbidium enters the sheathing part (vaginant lamina), which means that the border cells are separated from the margin by a row of chlorophyllose cells. This is called an intralaminar or intramarginal limbidium. The limbidium also connects with the costa at the leaf tip (leaf apex), forming an apiculus, or ending a few cells before the apex. The costa could be up to 25 micrometres at the base (per-current).[7]

Rhizoids are usually limited to the bottom of stems and brown in colour ± smooth rhizoids. Sometimes, papillose rhizoids have been reported to occur in F.limbatus.[7]

The synoicous in F.limbatus can be autoicous or dioicous. The archegonia could grow up to 240 μm long when the shoot is autoicous; whereas, the antheridia that are carried on short basal branches or unusually small axillary buds, its length range between 120–180 μm. Sporophytes are common in this moss and observed most of the time.[7]

The seta is yellowish-red a few millimetres thick (2–6mm) often and ~9 mm long.[7]

The sporangium capsule is very tiny 0.6-1 mm long that is erect or sometimes lightly curved, resembling a shape of an ellipsoid. The immature capsule of F.limbatus is green, and the operculum is fully and prominently enlarged above the annulus. The tip of the operculum is somewhat clear-green in colour. The capsule turns dark green to brown when maturing, except for the apophysis, keeps it light green colour and the operculum that turns red as each sporocyte has experienced meiosis and has produced four spores at this time.[8] The spores of this moss are minute 8–18 μm, yellow with a smooth texture.[7]

Peristomal teeth are present with 21–55.5 μm width at the opening of the capsule with filaments that are somewhat papillose and helical thickenings[7]