Plant of the Week: Azolla
Written By: Brooke Cherek
This Pointer Plant of the Week is the micro and mighty azolla! This freshwater aquatic plant is the world’s smallest fern, being between 1 and 2.5cm in length. Azolla is also one of the fastest growing plants around. It can double in size every 3 to 5 days.
This plant has specially adapted pockets that house a type of nitrogen fixing cyanobacteria called Nostoc Azollae. Based on fossil evidence, azolla and its cyanobacteria have co-evolved with each other for around 100 million years!
Despite its small size, azolla has played a major role in the temperature of Earth’s atmosphere. Approximately 50 million years ago, it covered a vast majority of the Arctic Ocean during the Eocene epoch. This was a period when the average atmospheric temperature was much higher than today, and the Earth experienced mass rainfall events.
During this azolla explosion, it is believed that up to half of atmospheric carbon dioxide was absorbed by this super-colony, ultimately leading to the cooling of the Earth into the next ice age event.
The earliest written record that mentions azolla is the Er Ya, a 2000-year-old Chinese dictionary. This plant was used as a nutritional supplement for livestock, such as pigs and chickens.
Within agriculture, azolla has also been grown alongside grains in rice paddies. The main reason for this is its ability to fix atmospheric nitrogen, which the rice can then use as a fertilizer. This method was developed by the Chinese a few thousand years ago and is still used today as an effective way to increase rice growth.
In 2018, biologist Kathleen Pryer ran a crowd-funded project to map the entire genome of azolla. This plant was found to have a whopping 720 pairs of chromosomes, which is 30 times the number of chromosomes that humans have.
Today, scientists are trying to find creative ways to use azolla to help curb climate change. One out-of-the-box idea is to try and recreate the azolla event from 50 million years ago in one of Earth’s oceans or seas.
There are many factors that make this plan tricky to carry out, including the invasive status of azolla in parts of the world and cross-country rules and regulations.
Brooke Cherek
Contributing Writer
