Spore structure and reproductive biology in Archidium alternifolium (Dicks. ex Hedw.) Schimp.

Abstract

The pattern of apparent curvature of cellulose microfibrils in TEM photographs of the multilayered intine of Archidium alternifolium showed variation between sections compatible with models suggesting regular rotation of the microfibrils in successively deposited sheets of wall materials. The intine extended inwards as a conspicuous ridge around the aperture on the proximal face of the spore of A. alternifolium, a feature not previously reported in mosses. Germination was uniformly through the proximal aperture. Little protonema was produced. The first shoot either emerged through the aperture, arose from a colourless protruberance developing immediately outside the aperture, or grew from a bud on protonema close to the spore. On agar, germination continued over a period of several months. Percentage germination was consistently less than 65%, and increased with the age of the spores up to four years in freshly collected material.

The origin of young shoots in a population of A. alternifolium at Stocks Reservoir was primarily by vegetative propagation, and shoot fragments predominated in the propagule bank in soil cores taken outside established colonies. Most spores produced in dense colonies of A. alternifolium at Stocks Reservoir appeared to be retained in the colonies, many of them in the parent perichaetia. The spores typically failed to germinate in that situation, but occasional sporelings with welldeveloped shoots were recorded in open colonies.