Grasses can also be very pretty, one just has to look close enough. Deschampsia flexuosa flowering on Iceland". Photo: Jan-Niklas Nuppenau

When you hear the word “grass” you typically think of a green lawn neatly grown in a garden or park. However, the world of grasses entails so much more. They are actually part of a family of flowering plants officially called Poaceae – typically not getting much spotlight in a non-scientific setting. Despite this, grasses are truly everywhere and human life as we know it is hard to imagine without them. We and other animals use them and especially their seeds, called grains, for food and many other purposes every day. To mention just a few examples of how grasses enrich our diet: bread (wheat), Sake (rice), popcorn (maize) and beer (barley). Not to forget their aesthetic and recreational values for sports and leisure as lawns, the use of bamboos as construction material and, increasingly, the production of biofuels such as ethanol from sugarcane and biogas from maize.

Since grasses are so nutritious and relatively easy to grow in huge quantities, they always played a vital role in human history. Emmer wheat and barley, for example, were among the first domesticated plants and allowed for the expansion of human kind. The famous historian Yuval Harari explains how agriculture and wheat changed our way of living:

"The body of Homo sapiens had not evolved for such [agricultural] tasks. It was adapted to climbing apple trees and running after gazelles, not to clearing rocks and carrying water buckets. Human spines, knees, necks, and arches paid the price. Studies of ancient skeletons indicate that the transition to agriculture brought about a plethora of ailments, such as slipped disks, arthritis, and hernias. Moreover, the new agricultural tasks demanded so much time that people were forced to settle permanently next to their wheat fields. This completely changed their way of life. We did not domesticate wheat. It domesticated us. The word “domesticate” comes from the Latin domus, which means “house.” Who’s the one living in a house? Not the wheat. It’s the Sapiens.” Yuval Harari

One aspect that makes grasses so important is that, in contrast to many other crops, some grasses, like rye, barley and oats, are also able to grow well in cold and seasonal climates. To be able to grow in these colder regions, it’s necessary for them to be cold tolerant and to survive abrupt changes in temperature, such as sudden cold spells in spring and fall. Jan-Niklas Nuppenau is a PhD student at DEEP, doing research on cold tolerance in grasses and has contributed his knowledge to this article.

1. Grasses are found almost everywhere on Earth

Grasses are found on almost every terrestrial surface, all continents and constitute over 11,000 species worldwide. This makes them one of the most species-rich families of flowering plants after orchids, daisies, legumes and the coffee family. So not only are grasses vital to humans, they are also hugely successful, both evolutionarily and ecologically.

2. Grasses dominate close to one third of Earth’s terrestrial surface

Grasses are tough and especially tolerant of grazing, mowing, periods of drought and light burning. The reason being that unlike most other plants, which have their main area of growth (called meristems) at their shoot tips, grasses’ meristems are located at the base of their leaves. This means that grasses can regrow fast after being mown or eaten.

Many grasses additionally have silica structures in their leaf blades, which discourages animals from grazing them and even makes some sharp enough to cut human skin.

Pampas grass, Cortaderia selloana, an example of a sharp grass leaf blade. Photo: Landcare Research. Published under the CC-BY 4.0 international license

Grasses are also very fast-growing, have up to hundreds or even thousands of seeds per plant and can grow as dense mats. These traits, along with others, have allowed them to outcompete other plants under favorable conditions and dominate ecosystems from savannas to tundras. Nowadays, grass-dominated ecosystems cover close to one‐third of Earth's terrestrial surface (about three times the size of Russia).

3. Grasses have been around for many millions of years

Jan-Niklas explains that grasses were already present when dinosaurs where still roaming around and, ultimately, outlived these animals:

“One of the oldest presumed grass fossils is leftovers in a dinosaur’s tooth”, reveals Jan-Niklas. There are different opinions, however, about the age of grasses:

“Based on the discoveries of new fossils, their age is estimated to be about 100 million years. The first flowering plants, which grasses are part of, evolved on Earth at least 140 million years ago and dinosaurs went extinct around 66 million years ago”, says Jan-Niklas Nuppenau.

A grass particle found in a dinosaur’s tooth. The red lines indicate silica structures typical for grasses. From a study by: Yan Wu, Hai-Lu You, Xiao-Qiang Li.

However, 66 million years ago the world was humid, warm and covered mostly by forests. It was long after the extinction of dinosaurs, though, that grass-dominated vegetation is thought to have become widespread, from around 35 million years and onwards. At that time Earth started getting cooler and dryer, with a more seasonal climate toward the poles. These climatic conditions limit the growth of forest and favor the growth and dispersal traits of grasses described above.

4. Grasses can afford not to be showy

“Grasses produce a lot of pollen that is dispersed by wind. It means they don’t have to be flashy and show off for bees and other pollinators, like animal pollinated flowers do. The pollen reaches another plant of the same species by wind and fertilizes it”, explains Jan-Niklas Nuppenau.

This sort of pollination means that the pollen is very good at flying and can land anywhere. It can be problematic for people with allergies though. The grasses themselves can be miles away from people and their pollen can still reach them.

5. Grasses make up more than 50% of the world’s food demand

“There are many economically important crop and forage grasses. Examples include commonly grown ones, such as wheat, sugarcane, maize and rice. These crops alone make up for more than 50% of the world’s food demand. In colder climates people are also able to grow barley, which is important for bread and, especially, beer production”, says Jan-Niklas. To increase yields, people have made a lot of changes to grasses during their domestication.

Barley. Photo: Neal Alderney

Livestock, such as sheep, cows and horses also benefit from grasses - when let out in the meadows they forage grasses such as timothy and ryegrass. Ryegrass is also the common lawn grass.

Sheep eating grass on a meadow in Iceland. Photo: Jan-Niklas Nuppenau

6. Grasses can be very cold tolerant

A number of grass lineages are very successful in cold ecosystems and can be found on the highest latitudes and altitudes where plants can grow. One species can even grow in Antarctica. Deschampsia antarctica, or Antarctic hair grass, is one of only two vascular plants there.

Stay tuned for our next blog post were Jan-Niklas goes more into detail about cold tolerance and how grasses growing in geothermally heated areas of Iceland can help us understand more about the evolution of thermal tolerances, tolerance of heat as well as  cold.