Tag: plant kingdom

Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialised structures called gemmae.

Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialised structures called gemmae.

Mosses occupy a wide range of habitats. Mosses are typically found in moist environments although most species can withstand prolonged periods of desiccation. In terrestrial ecosystems, Mosses are important in preventing soil erosion. Numerous species of Moss are found in fresh water but there are no salt water species.

Funaria exhibits gametophytic (n) as well as sporophytic (2n) generation in its life cycle. The gametophytic (haploid) generation is represented by a short-lived protonema which produces spermatozoids in antheridium of male shoot and egg in archegonium of the female shoot.

Peristome (exposed) plays an important role in the dispersal of spores. The peristome teeth by their hygroscopic movements help in the discharge of the spores. The inner peristome simply functions as a sieve. The spores are liberated in the dry weather and are carried out by air.

In Funaria, spore has small irregular mitochondria, numerous chloroplasts with poorly developed lamellae, small sparsely present dictyosomes and ER in the form of highly convoluted tubules near the plasma membrane.

The mature sporophyte of Funaria is much more complex than that of the liverworts. It is differentiated into foot, seta and capsule. The foot forms the basal portion of sporophyte. It is a small, dagger-like conical structure embedded in the tissue of the tip of the leafy female branch and functions both as an anchorage and an absorbing organ. The seta is a long cylinder but tough, reddish brown, stalk-like structure. It carries the capsule at its top and raises it more than an inch above the apex of the leafy gametophore. The capsule is a highly organized structure. It is pear-shaped and green at first but later turns yellow, and then orange. Its upper portion is covered by a conical hood or a cap, the calyptra. At maturity, the calyptra falls off laying bare its apex. 

Sphagnum has no seta. In Sphagnum and other basal mosses, the sporophyte is raised by the pseudopodium, a structure produced by the parent gametophyte.  

The sporophytes of mosses, like those of the liverworts, consist of a foot, seta and capsule and remain permanently attached to the gametophytes. At the tip of the capsule is a lid (operculum) which, prior to spore dissemination, falls away exposing the so-called peristome teeth, a set of structures, often delicate and thread-like in appearance, that form a ring around the mouth (rim) of the capsule. The peristome teeth are perhaps the most characteristic feature of the mosses; usually composed of cell wall remnants, they respond to changes in the humidity of the atmosphere. When a moss first grows from the spore, it grows as a protonema, which develops into a leafy gametophore.