Question

Describe the internal structure of the funaria capsule.

Answer 1

Hint: The species Funaria is commonly referred to as 'cord moss' which belongs to the class of Bryopsida and the family, Funariaceae. It is mostly found growing in the trunks of trees, on rocks, damp walls and in moist soils which helps in the process of soil formation called Pedogenesis.

Complete answer:
The internal structure of matured sporophyte of Funaria is complex which is further categorized into three distinct parts namely foot, seta and capsule.
Foot: It is located on the basal part of the sporogonium. It looks small, conical in shape which is embedded in the gametophyte on the apex of a female branch. Its role is to anchor and absorption of nutrients
Seta: It is a very long, slender, stalk-like reddish brown structure which is hygroscopic in nature. It held the capsule at its tip. Its main role is to conduct the water and nutrients to the developing capsule.
Capsule: The most terminal part of the sporophyte is a capsule which is formed at the apical region of the seta. It has a pear-shaped structure which is covered by a cap like structure called calyptra, which falls off later.
The capsule consists of three distinct regions namely apophasis, theca and operculum.
Apophasis: It has a thick basal sterile part of capsule which is bounded by a thin-walled epidermis interrupted by stomata. Below the epidermis, there exists a spongy parenchyma which contains chloroplasts and the cells of apophasis are photosynthetic. This region constitutes the neck of the capsule which connects with the seta.
Theca: This is an urn-shaped, spore-bearing region of capsule which lies in between the apophasis and operculum. It has single layered epidermis and more layers of compactly arranged colourless cells in the hypodermis. There are spongy parenchyma cells which contain chlorophyll that can perform photosynthesis. There are air spaces which contain parenchymatous cells (green cells) known as trabecular cells. The presence of spore sacs which have the cavity with outer and inner walls. At maturity, the spore mother cells in the cavity produce haploid spores. Then the central region of theca is known as the columella which has colourless parenchymatous cells. It helps in the transport of water and mineral nutrients.
Operculum: This is present on the upper dome-shaped region of the capsule which consists of more layers of cells. The outer region is thick walled called epidermis. There are well marked constriction and a diaphragm (rim) which separates the cells of operculum and theca. It has teeth-like projections made up of cuticles which are arranged in the form of a ring near the diaphragm called peristome. There are thin walled parenchymatous cells which are placed inner to the peristome teeth.

Note: The sexual reproduction of Funaria is oogamous in which the female reproductive structure is termed as archegonium and male as antheridium. Funaria have both male and female sex organs on the same thallus and are considered as monoecious.