Phenology is interpreted as the study of the timing of growth and reproductive events, and it underpins a great proportion of the field of reproductive ecology. Salient early works in bryophyte phenology provided broad-based compilations of important phenological characteristics for entire local bryofloras in Germany and European regions, including branching architecture, the timing of vegetative growth, gametangial initiation times, fertilization times, the duration of sporophyte development, and the time of spore liberation. Recent work in the field was incited by the formulation of a phenological classification system for mosses proposed by Stanley Greene and placed into context by Royce Longton. Phenology in the broad sense is seen to intersect the fields of stem architecture, growth rates, nutritional status, structural development, population dynamics, fertilization biology, fitness measures, the interplay between sexual and asexual reproduction, spore dispersal patterns, sex dimorphism, clinal variation, and desiccation tolerance, among others. The principal patterns of gametangial and sporophytic maturation are reviewed, and a “consensus system” for presenting phenological data is presented that combines the categories of maturation postulated by Greene, the functionality stressed by Forman, and the numerical basis refined by Longton. The field of phenology has a bright future inasmuch as the research continues to focus on individual species and seeks to branch out into the fertile disciplines of sex expression, sex ratios, and resource distribution. The most useful tool for the bryophyte phenologist in investigations of these disciplines may very well rest with allocational bryology.