Genus CalostomaGENUS CALOSTOMA
This genus has but three known American species. The plants are remarkable in structure e and substance. The spore mass or gleba lies at the centre of a base, and is in its young stages surrounded by four Livers. The outermost coat is gelatinous, and soon disappears. This is known as the volva or wrapper. The layer just within the wrapper also soon disappears; it is known as the exoperidium. The layer just within the exoperidium is known as the endoperidium, and is the Liver seen on the exterior of older specimens. Between the exoperidium and endoperidium is a layer of red threads, part of which is torn away when the exoperidium breaks, and a part of which remains as a red star at the apex of the ball.
The exoperidium is cartilaginous; it is thin and fragile when dry, but when wet it is flexible, translucent, and soft. The endoperidium is hard and rigid when dry, and is conspicuous for the brilliant red which shows at its mouth. Within the endoperidium is a sac which contains the spores; when the spores are mature, this sac contracts, and forces the spores out into the air. The mycelium, or vegetative part of the Calostoma plant, is composed of numerous cord-like fibres, translucent, jelly-like, and tough, which, branching and anastomosing into a dense net-work, form a rooting columnar base to the spore-bearing part of the plant. The name Calostoma means beautiful mouth, referring to the red star which surrounds the opening through which the spores escape.