The question of what constitutes the “most common plant” on Earth is more intricate than it initially appears. The answer depends significantly on how “common” is defined.
The Challenge of Defining “Common”
Defining “common” for plants involves various metrics. One interpretation focuses on total biomass, measuring the sheer weight of plant material globally. This metric often points to large, long-lived plants.
Another perspective considers the number of individual plants, counting distinct organisms regardless of their size. This approach highlights species that reproduce prolifically and spread widely. A third definition examines geographical distribution, identifying plants found across the widest range of environments.
Finally, human cultivation introduces another layer of commonality, focusing on plants extensively grown for agriculture. These plants might not be naturally widespread but dominate vast areas due to human intervention. Each definition offers a unique lens to view plant prevalence.
Leading Contenders for the Title
Different metrics for commonality bring forward distinct plant species as leading contenders. When considering total biomass, land plants account for approximately 80% of Earth’s entire biomass, estimated at around 450 gigatons of carbon, with woody stems and tree trunks making up a significant portion. Forests, particularly tropical forests, contain an immense amount of biomass. Dominant tree species in vast forest ecosystems, like those in the Amazon or boreal forests, contribute to the planet’s overall plant mass.
For individual plant count or widespread distribution, species often considered “weeds” or pioneer plants emerge as strong candidates. Plants like dandelions, white clover, and quackgrass are adaptable and thrive in diverse environments, from gardens to disturbed landscapes. Bracken fern (Pteridium aquilinum) is another contender, known for its extensive spread across all continents except Antarctica, often thriving due to human-influenced disturbances. Such plants possess resilient reproductive strategies, allowing them to rapidly colonize new areas.
Human cultivation changes the landscape of plant commonality, with staple crops covering immense agricultural areas. Wheat, for example, occupies the greatest land area of any single crop, covering over two million square kilometers globally. This extensive cultivation means a single wheat field can contain trillions of individual plants worldwide. Rice and corn (maize) are also globally significant, feeding nearly half of humanity and being the leading grain crop harvested globally. These crops are important for global food security, making them common due to human reliance and widespread farming practices.
Why Certain Plants Dominate
The widespread dominance of certain plant species stems from a combination of biological traits and ecological factors. Adaptability plays a role, allowing these plants to thrive across a broad spectrum of climates and soil types. Plants capable of tolerating varied environmental conditions are more likely to establish and spread successfully.
Effective reproductive strategies are another factor in plant commonality. Many dominant plants exhibit high reproductive output, producing numerous seeds that can be widely dispersed by wind, water, or animals. Some also employ vegetative propagation, such as rhizomes or stolons, enabling rapid clonal growth and quick colonization of an area without relying on seeds.
Resilience contributes to their success, as these plants can often recover from disturbances like drought, disease, or physical damage. Their ability to persist in challenging conditions allows them to maintain populations where less robust species might perish. Human influence, both intentional and unintentional, also contributes to the commonality of many plants. Agricultural practices, urbanization, and global transportation facilitate the spread of cultivated crops and opportunistic “weed” species. These human activities create disturbed habitats that many adaptable plants readily exploit.