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Eudicots

life science Maturity 5-7 Next article →

Eudicots are a massive group of flowering plants. They belong to a large category called angiosperms. This group makes up over 70% of all known angiosperm species. The name "eudicot" comes from the term "true dicotyledon." This refers to the two seed leaves, or cotyledons, that appear during germination. These plants are essential to life on Earth. They include many of the trees, flowers, and foods we use every day.

Arabis voch1-4
Arabis voch1-4

Scientists identify eudicots by looking at their pollen grains. These grains have a very specific structure. Eudicots possess three grooves called colpi that run along the polar axis. These grooves are a type of pollen aperture. An aperture is a modification in the pollen wall. These openings serve two main purposes. They allow the pollen contents to exit the grain. They also let the grain swell or shrink based on moisture levels. Other plants, like monocots, usually have monosulcate pollen. This type of pollen has only one groove, called a sulcus.

Arabis voch1-4
Arabis voch1-4

Understanding the history of these plants requires looking at both fossils and genetics. Evolutionary botanist James A. Doyle and paleobotanist Carol L. Hotton introduced the term "eudicots" in 1991. They wanted to highlight how these plants diverged from earlier, less specialized dicots. Before this, scientists often used the name "tricolpates." This name specifically described the three-groove pollen structure. Today, the term eudicot is used in major classification systems. These include the APG systems, such as APG IV from 2016. These systems help organize the vast diversity of flowering plants into a single family tree.

Arabis voch1-4
Arabis voch1-4

We can trace the ancient lineage of eudicots using a molecular clock. This tool helps scientists estimate when different plant groups split apart. Calculations suggest the eudicot lineage split from other plants about 134 million years ago. Some estimates place this split even earlier, between 155 and 160 million years ago. The fossil record provides even more evidence of their ancient history. Fossil evidence suggests that basal eudicots were already a very diverse group by 121 million years ago. This shows they have been a major part of the Earth's biology for a very long time.

Arabis voch1-4
Arabis voch1-4

One fascinating way scientists define eudicots is through their DNA. A specific genetic trait defines this group. It involves the duplication of DELLA protein-encoding genes. This duplication occurred in their most recent common ancestor. This genetic marker helps confirm the evolutionary relationships found in morphological studies. Morphological studies look at physical shapes, such as the tricolpate pollen. By combining physical traits with genetic evidence, botanists can be sure of how these plants are related.

Arabis voch1-4
Arabis voch1-4

Eudicots are divided into several distinct groups. Scientists often separate them into basal eudicots and core eudicots. The core eudicots are a monophyletic group, meaning they include a common ancestor and all its descendants. A 2010 study suggested the core eudicots can be split further. One group is called Gunnerales. The other is a large group called Pentapetalae. The Pentapetalae is then divided into two main branches. These are the superrosids and the superasterids. Each of these branches contains many smaller, specialized groups.

Arabis voch1-4
Arabis voch1-4

We interact with eudicots constantly in our daily lives. Many common edible plants belong to this group. You might eat cabbage, apples, or macadamia nuts. Many beautiful flowers are also eudicots, such as sunflowers, dandelions, and forget-me-nots. Most leafy trees found in mid-latitude regions are eudicots, including maples and buttercups. There are exceptions to this rule, however. Trees like the magnolia and the American tulip tree belong to the magnoliids instead. This shows how diverse the world of flowering plants truly is.

Arabis voch1-4
Arabis voch1-4
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