Question

The dehiscence of the moss capsule takes place by rupture of the ___.
A. Operculum
B. Peristome
C. Annulus
D. Calyptra

Answer 1

Hint: Moss is a plant that produces small capsules of spores with no flowers and no fruits. Mosses don't have seeds and develop spores that are encapsulated in a single capsule after fertilization. In a division with hornworts and liverworts, mosses and hornworts are considered "nonvascular" plants with haploid gametophyte generation as their dominant phase of life.
Complete step-by-step answer: In its early developmental stages, the sporophyte is completely covered with a tough coating called the calyptra. Sporophytes shed their calyptra when they become mature, revealing their capsules. During spore dissemination, the lid of the capsule falls away, exposing the so-called peristome teeth, structures that are often delicate and thread-like in appearance and form a ring around the mouth (rim) of the capsule.
During dehiscence, the annulus of the moss capsule ruptures. The endothecium in moss capsules functions similarly to the endothecium in anthers during dehiscence. The spores are ejected from leptosporangiate ferns via an annulus surrounding the sporangium. There is no specialized mechanism for dehiscence in Eusporangiate ferns.
Therefore, the correct answer is option C- Annulus.
Note: The majority of mosses reproduce by alternating between sexual and asexual generations, each generation requiring two generations to complete the life cycle. In the protonema, the sexual form, the gametophyte (producing haploid gametes), is formed. Upon spore germination, the protonema forms, giving rise to the green, leafy plants commonly referred to as mosses. Asexual forms, or sporophytes (which produce diploid spores), develop as separate males and females, but each cannot exist alone.