The evolution of plants can be seen during a stroll through the woods.

Shaded woodlands, where competition for limited resources is high, seems like an unlikely place to see the most ancient land plants and their evolution. However, the first land plants have been so successful that many of their ancestors are still plentiful in the understory of today’s forests and might even help forests mitigate the effects of climate change today. 

Charophycean green algae are believed to be the ancestors of all land plants. These unicellular organisms appeared about 2.7 billion years ago, are plentiful in ponds and other water sources and serve as the base of the food chain. Interestingly, it is believed that the first photosynthetic bacteria appeared around 3.4 billion years ago, absorbed infrared light rather than visible light and produced sulfur rather than oxygen.  Photosynthesis most likely evolved via a process of endocytosis where photosynthetic bacteria was taken up by larger cells and converted into an organelles.  There is evidence that this process of endocytosis has occurred more than once in evolution.  

It is believed that the first land plants developed a symbiotic relationship with fungi about 500 million years ago, which served as the precursor to plant roots.  [Entangled Life, c2023, Merlin Sheldrake]

Several adaptations appear to have occurred as plants moved out of the water onto land.

1. alternating haploid and diploid generations
2. sporangia, a reproductive sac that houses the diploid spores.
3. gametangia, structures on the gametophytes that produce the haploid sperm and eggs.
4. apical meristem in roots and shoots, undifferentiated cells that allow continuous growth.
5. a cell wall containing lignin
6. a waxy cuticle

The first land plants belong to the division, Bryophytes.  Lacking a vascular system, these plants remained small and are seen in today's forests as mosses, lungworts and hornworts. The park service in North Carolina has a website dedicated to Bryophytes, which includes a list of species that have been found in each county of the state.  

The development of a vascular system gave plants the ability to transport water and nutrients across large distances, which allowed them to grow in size. Among the first plants to achieve this evolutionary milestone are the ferns, another group of plants that we commonly find in the woods. Many of the first ferns were tree ferns, appearing in the Devonian period.  However, most ferns that we see today co-evolved with the Angiosperms (seed-bearing, lowering plants) during the Cretaceous.

A recent study reported that ferns have exhibited bidirectional evolution, sometimes evolving in the direction to more primitive forms.

Science News reported on a study January 6, 2025 entitled: Hornwort genomes provide clues on how plants conquered the land.