The Stages of a Wilting Flower

Flower Stages

• Flowers begin to form after a plant has completed its main vegetative growth for the season. The terminal buds become flower buds instead of leaf buds. This is called the R-1 stage. The bud elongates and swells and begins to grow in size over several stages, culminating in the R-4 stage where the flower begins to open. The flower is full and receptive until the R-6 stage where it begins to fade. The outer petals wilt first and the flower changes color slightly. The texture of the leaves changes and gets more delicate. The petals fall but the ovary is undergoing changes even as the flower fades. The stages of R-6 to R-9 are called senescence.

Changes When a Flower Wilts

• Two hormones produced by flowers regulate their life cycle. One is abscisic acid and the other is ethylene. Different species are driven by different hormones which signal the flower to begin changing and preparing fruit. The petals increase their oxidative rate, lose membrane permeability and decrease production of protective enzymes. Pollination and environmental stress encourage the wilting by changing the hormonal balance. This initiates the fading bloom, wilting and shedding of petals.

Sugar Starvation

• During senescence, flower petals receive less starch and proteins, and lipids are more rapidly utilized. The starch is a component of carbohydrates which are the plant sugars harvested and synthesized during photosynthesis. The flower begins to starve as it receives less nutrition and petal cells die. The process can be stalled slightly as in the case of cut flowers. They will hold longer when the water solution has sugar added to it, but wilting will occur in due time. The effects of added sugar are more pronounced in flower species whose senescence is regulated by ethylene. The sugars delay the rise in ethylene production that occurs as the petal begins to wilt by decreasing ethylene sensitivity.

Final Stage

• Provided the flower is pollinated during the middle of its life cycle or before R-6, the ovary will begin to swell. The petals have fulfilled their obligations and begin to wilt and fade, due to hormonal changes. Inside the ovary are the ovules which will become seeds. Inside each ovule is the embryo which divides numerous times as it develops. The embryo will eventually become a plant in the same species as the flower. As the ovary swells during all this development, the petals and sepals fall off, leaving the fruit or seed capsule of the plant.