Fruit maturation, not deteriorating light conditions, is the primary cue of senescence in a spring ephemeral annual plant--Floerkea proserpinacoides (Limnanthaceae)

In monocarpic plants, reproduction is closely associated with senescence, which is itself often correlated to specific environmental signals. Floerkea proserpinacoides (Limnanthaceae) is a spring ephemeral annual of the deciduous forests of eastern North America. The phenology of its growth and reproduction is considered to be a specific adaptation to the short period during which there is a high availability of resources (mostly light). Indeed, flowering starts 2-3 wk following seedling emergence soon after snowmelt and continues until tree canopy closure. However, fruit maturation is postponed for several weeks and is followed by the plant's death. The objective of this study is to determine if senescence in F. proserpinacoides is primarily cued by fruit maturation or deteriorating light conditions associated with tree canopy closure. Plants for which reproductive investment was manipulated by removing their carpels were grown either in full light or in the shade. Carpel-removal plants reached a higher biomass than control plants (46.0- 57.5% higher), especially in full light. However, longevity was greater in carpel-removal plants, particularly in the shade (25.3-37.8% greater). These results thus suggest that fruit maturation, not deteriorating light conditions associated with canopy closure, is the primary cue of plant senescence in F. proserpinacoides.