Question

Using full and complete sentences please explain the method of spore dispersal in a “typical” moss

Answer 1

Answer-

According to the given question-

• Mosses have dominant gametophytes phase in their life cycle.
• They do not have vascular tissue and are generally attached to a central stalk or also called seta. They also follow alternation of generations.
• Gametophyte which is haploid, germinates form spore which are also haploid and are formed due to meiosis. Sporophyte generation in moss is very short-lived and has a capsule responsible for producing spores through meiosis.
• Released spores are dispersed through air currents and when they reach on suitable surface such as having moist they germinate and lead to gametophyte generation.
• Spore is changes into protonema which is a filamentous stage having chloroplasts. Capsule of moss made up of several tissues.
  

Spore Dispersal Mechanism-

The capsule of mass has operculum and peristome except Graphite mosses. When there is presence of dry conditions it occur in following sequential steps-

• First the remains of Archegonium which is called calyptra drops off
• Then due to loss of water by annulus the operculum is shed
• This leads to outward bending of peristome teeth
• Now due to bending the spores fall from the capsule and spread with the help of air currents

Bending of peristome teeth is due to presence of triangular structures which work as trap-door mechanism. Here it have two layer ,   One layer at a time either releases or absorb moisture and at same time other have opposite effect and this leads to water loss at one side and from there is no loss of water , due to which the peristome teeth contract or shrinks which causes ou Word bending of teeth.