Pollen malformations have been proposed as a paleoenvironmental stress proxy. However, the frequency and variability of pollen malformations under near-optimal conditions and environmental stress, as well as their developmental origins, remain unclear. To bridge these gaps, we compared pollen malformation frequencies and assemblages of 14 extant conifer genera of Pinaceae and Podocarpaceae producing saccate (winged) grains grown under near-optimal conditions. These baseline pollen yields were compared with those produced by Pinus mugo ‘Columnaris’ cultured under...