Introduction:
The moss capsule is a reproductive structure found in mosses. It is responsible for the production and dispersal of spores, which eventually develop into the haploid gametophyte generation. The capsule consists of several parts, each with its own specific functions. Among these parts, the calyptra, operculum, annulus, and columella play crucial roles in the reproductive process.

1. Calyptra:
The calyptra is a protective hood or cap-like structure that covers the apex of the moss capsule. It is derived from the archegonial venter, which is a part of the female reproductive structure. The calyptra is diploid, as it is derived from the fusion of the egg and sperm during fertilization. Therefore, the calyptra is not haploid.

2. Operculum:
The operculum is a lid-like structure that covers the opening of the moss capsule. It helps protect the developing spores inside the capsule and controls their release. The operculum is also diploid, as it is derived from the sporophyte generation. Therefore, the operculum is not haploid.

3. Annulus:
The annulus is a specialized ring of cells located just below the operculum. It plays a crucial role in the dispersal of spores. The annulus cells have thickened walls and are hygroscopic, meaning they have the ability to change shape in response to humidity. This change in shape causes the annulus to contract and expand, creating pressure within the capsule. Ultimately, this pressure is responsible for the ejection of spores from the capsule. The annulus is diploid and not haploid.

4. Columella:
The columella is a central column-like structure found inside the moss capsule. It provides support and helps maintain the shape of the capsule. The cells of the columella are derived from the sporophyte generation and are therefore diploid. Like the calyptra, operculum, and annulus, the columella is not haploid.

Conclusion:
Among the mentioned parts of the moss capsule, none of them are haploid. The calyptra, operculum, annulus, and columella are all derived from the sporophyte generation and are diploid structures. The haploid structures in mosses are the spores themselves, which are produced within the capsule and are eventually released for germination and the development of the haploid gametophyte generation.

Annulus