Article: Late Devonian winged preovules and their implications for the adaptive radiation of early seed plants

Winged preovules, preserved as compressions, have been recovered from the upper Famennian of Sauerland in central Germany. Preovule organization of Warsteinia paprothii gen. et sp. nov. includes a nucellus with distal hydrasperman lagenostome and a preintegument comprising four alate lobes. The hydrasperman organization appears to be similar to that of other well-documented Late Devonian and Early Carboniferous preovules. The alate preintegument morphology is comparable to that of permineralized preovules, such as Lyrasperma scotica and Euryostoma burnense from the upper Tournaisian of Scotland. The preintegument is differentiated into a dense inner and fibrous wing-like outer zone. The Devonian preovules represent the earliest evidence of a winged plant diaspore, and the differentiation of a preintegumentary sclerotesta and sarcotesta could be regarded tentatively as an adaptation to optimize wind-mediated dispersal. The variety of integument structures following the earliest preintegument suggests that the system of unfused, terete preintegument lobes among earliest seed plants represented an important pre-aptation for a range of functions including protection, optimization of pollination, and dispersal.