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- Title
Timing of shoot senescence and demographic expression in the clonal perennial Podophyllum peltatum (Berberidaceae)
- Authors
Lu, Y.; Watson, M. A.
- Abstract
The timing of leaf senescence may be imposed by the environment or controlled internally by the plant; the latter form of senescence we term endogenous senescence. Controls on the timing of endogenous senescence may reflect an evolutionarily derived compromise between the plant's carbon and mineral nutrient requirements. To examine the validity of this hypothesis, we examined the relationship between variationin mean shoot senescence time and demographic status in the long-lived perennial understory herb, the mayapple, Podophyllum peltatum. We found that mean shoot senescence time extends over a 30-d period, with the timing related to the recent history of the rhizome system, thedemographic status of the current shoot, and the demographic status of the terminal bud on the extending rhizome axis (i.e., whether it will form a sexual or vegetative shoot in the following year). We found that (1) sexual shoots senesce later than vegetative shoots; (2) fruiting shoots senesce later than sexual shoots without fruits; and (3) shoots on rhizome systems where last year's rhizome segment was larger senesce later than those with a shorter ultimate rhizome segment.Of particular interest are our observations that (4) current shoots that give rise to larger new rhizome segments senesce later than those that give rise to smaller ones and (5) current shoots on rhizome systems that give rise to sexual new shoot buds senesce later than those that give rise to vegetative ones. We conclude that, in mayapple, the timing of endogenous shoot senescence is influenced by current andfuture reproductive status as well as the past and current vigor of the rhizome system. The patterns of relationship that we identify areconsistent with the hypothesis that carbon rather than mineral nutrients is the resource most limiting mayapple growth. Significant differences in mean shoot senescence time also were detected among colonies and among years. These differences suggest the existence of genotype and
- Subjects
PLANT ecology; PODOPHYLLUM peltatum
- Publication
Oikos, 1999, Vol 86, Issue 1, p67
- ISSN
0030-1299
- Publication type
Article