It ain't over 'til the fat cell sings
![[Corel] A cut rose lives on](2002-06-14-yellow-rose.jpg) Q: In the absence of clear life signs (respiration, circulation, etc.), how do botanists decide when a plant
is no longer living? For example, is a freshly picked rose considered dead?
(Ben R., Albuquerque, New
Mexico)
A: A freshly picked rose is not dead. Plant cell metabolism doesn't stop when someone cuts the rose. If it
did, the buds would not open when you place the rose in a vase of water.
[Corel] A cut rose lives on
Even grass chewed and swallowed by a cow is not immediately dead says Alison Kingston-Smith, a
microbiologist at IGER (Institute of Grassland and Environmental Research in Aberystwyth, Wales, UK).
It's a tough world inside the first stomach of a cow (the rumen). The temperature is a sweltering 102 degrees
Fahrenheit (39 degrees Celsius). No air. Enough stomach acid to drown in. However, plants die slowly.
They're programmed to adapt to a changing environment. As the grass struggles in the rumen, it lives long
enough to release nutrients for the cow's microbes and to die an orderly death.
When is a plant dead? Before we answer this, let's consider how a cell works. A film-like membrane surrounds each cell. Chemical and
electrical gradients exist across the membrane that cause nutrients to pass into the cell and wastes to leave the cell. The two-way traffic is
essential for the cell to make energy and therefore survive.
A plant is certainly dead when all of its cells cease producing energy and their cellular membranes are no longer intact.
Is a plant dead if all but 1% of its cells are dead? Probably, says Andrew Groover geneticist from the USDA Forest Service in California.
"However, many plant cells are 'totipotent,' meaning a single cell can give rise to a whole new plant."
(Answered Jun. 14, 2002)
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