Unlike humans and animals, not all plants are limited to the same lifespan. Plants die of old age, but they can also live for millenia if the environmental conditions are right.
How Long Can Plants Live?
Plants do not have definite lifespans. Others die within a few months while others survive for hundreds or thousands of years.
Compared to animals and humans, plants have indeterminate growth. This means that there is no specific age or size for a plant to be considered mature or at old age.
However, this ability to last long has two limitations. First, a plant may no longer be able to send water to all parts because of the lack of water pressure in the xylem, one of the two transport tissues in vascular plants. Second, it may not be able to support the weight of its body at a certain point, something that is seen with trees, which branch out too much.
The oldest potted plant ever recorded is a prickly cycad, which was planted in 1775. Meanwhile, plants in the wild can live longer, such as the 4,850-year-old bristlecone pine tree in California named Methuselah.
According to the Royal Horticultural Society, plants can be classified into three groups according to their life expectancy. These groups include annuals, biennials, and perennials.
Annual plants are those that grow, produce seeds, and die within one year, while biennials survive for two growing seasons. On the other hand, perennials are those which can live longer than annuals and biennials.
In the New York Times Science Q&A column in 2018, author C. Claiborne Ray wrote that the life span of plants is highly variable, with some trees achieving what looks like immortality. One thing that makes plants different from animals is their growth areas, called meristems, which can stay forever young and renewable.
Meristems refer to plant tissues composed of unspecialized cells which are capable of cell division. They contain stem cells which can become any type of specialized cell. This means that they have the ability to regenerate parts of the plant as needed.
Senescence in Plants
No matter how a plant is cared for or how genetically predisposed they are to live long, they will perish at some point due to the process of senescence. Over time, their cell division slows and stops. As a result, they will fail to renew their parts and ultimately die.
In humans, old age and death is usually characterized by a lack of brain cell function. While plants do not have brains, they undergo a process called senescence.
Senescence starts when the telomeres in the DNA shorten. These DNA caps shorten until there is no more left to protect, resulting in a release of proteins within the plant. These proteins then cause apoptosis, which leads to cell death.
There are several factors that can affect senescence. For instance, aging can be promoted by plant hormones or growth regulators. Seasonal and environmental cues can affect the balance of these hormones, which can trigger biochemical processes within the plant.
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