Spore development during capsule maturation of three Riccia species

Abstract

Berg, C. & Pöltl, M. 2020. Spore development during capsule maturation of three Riccia species. – Herzogia 33: 179 –187.Ricciaspores develop during sporophyte growing and maturation. In young capsules, the spores have not yet archived their final size, color and ornamentation. These are important features for the determination. We ask, at which stage of development the spores show their final features, and how bryologists can recognize this. With the help of light microscope photography, we measure and describe spores taken from young, mature and open capsules. Young capsules exhibit a lighter color and do not bulge above the thallus surface. Riccia-spores reach their final size, ornamentation and color in mature capsules. Mature capsules are mostly dark, and bulge above the thallus surface. They remain globose after drying as herbarium specimens. According to our study, the spores of such capsules show the same final features as spores in open capsules. They are suitable to measure spore size and examine the characteristic ornamentation and color of the exospore.