Plant science in...

Pride in plant science

This month is Pride Month and this weekend would have been London Pride, a parade designed to celebrate the LGBT+ community. Unfortunately, due to Coronavirus, Pride had to be cancelled. Because I can’t show my support in the streets, I’m showing my support here. Inspired by the Rainbow Flag, we’re going to look at six colourful plants, each covering topics from ecology to biochemistry.

Red Bottlebrush

We’re kicking off with Bottlebrushes (Callistemon), a group of shrubs from the myrtle family (Myrtaceae). Their name, unsurprisingly, comes from the fact that they look like bottle brushes. All Bottlebrushes are endemic to Australia, meaning that this is the only place in the world where they are native.

The Latin name ‘Callistemon‘ comes from a joining of two Greek words: ‘kallis‘ meaning beautiful and ‘stemon‘ meaning stamen. Stamens are the pollen producing part of the flower, and on a Bottlebrush, these are the countless, projections responsible for its iconic look.

Bottlebrushes are an example of bushfood, meaning food used by indigenous Australians for sustenance or medicine. Nectar from some Bottlebrush species was used by indigenous Australians to produce a sweet drink. This nectar can either be consumed by sucking on the flowers or soaking them in water. Some species are also used to make tea.

Orange Strawflower

Staying in Australia, the next plant on our list is the Strawflower (Xerochrysum sp.). Strawflowers are now cultivated worldwide and come in a variety of beautiful colours. They’re an insect utopia, providing food and shelter for butterflies, hoverflies, bees, beetles and grasshoppers.

Strawflowers are named as such, because of the straw-like texture of their bracts. Even the genus name of Xerochrysum bractium is Greek for ‘dry-‘ (xero) ‘-golden’ (chrysum) ‘bract’ (bractium). Like daisies, the centre of the inflorescence is actually made up of hundreds of tiny flowers. The ‘petal’-like structures surrounding this is actually made up of a row of bracts.

In folklore, this plant is thought to be immortal because when dried, the flower remains largely intact. This is due to the inflorescence having bracts rather than petals, as they are better at maintaining their shape upon drying. This gave them their other common name, the Everlasting Flower.

Yellow Sunflowers

Sunflowers (Helianthus sp.) orginiated in the Americas and have brilliant, sunshine-yellow flowers. They belong to the daisy family (Asteraceae) and just like their daisy cousins, they’re not one singular flower, but a composite flower, made up of many flowers. Like us, sunflowers have something of a circadian rhythm, in that they respond to the changes in light throughout the day.

Immature flowers track the sun across the sky, from east to west. Once the sun has set, the flowers return to face the east, ready to track the sun the next day. As the plant matures and the stem stiffens, the flower gets fixed in the eastern direction. This process is called ‘Heliotropism’.

In Greek mythology, it was believed that this was caused by Clytie and Helios. Clytie, a water nymph, fell in love with the sun god Helios. She would watch him race across the sky in his golden chariot, and after nine days became rooted in the ground where she became a sunflower.

Green Sea Spurge

A common staple on many sandy beaches is Sea Spurge (Euphorbia paralias). Life by the sea can be difficult for a plant. Water is salty, the ground is unstable and stormy winds blow you about. But coastal plants like Sea Spurge have a few tricks up their s-leaves (*ba-dum tsss*).

This plant is an example of a pioneer species, meaning they’re the first to colonise an area. In order to do this, they have long roots which spread sideways. This helps them to stabilise the sandy ground. Once the soil is stable, other species to grow around them. When you look at the coastline from the sea inward, you’ll be able to see bands of species.

Sea spurge plants have upright, closely packed stems, which act as a windbreak. They also have thick, fleshy leaves to help them retain water. Their roots are sometimes moved by waves or the ground, but they just reestablish in their new location. Their seeds can get washed out to sea, where they will float for years before eventually finding new land to colonise.

Blue Himalayan Poppy

Himalayan poppies (Meconopsis sp.) are a genus of poppy with unmistakable, sky blue flowers. The genus name was given to these flowers before they were known to be poppies. Viguier, a French botanist created it from ‘Mekon’ meaning ‘poppy’ and ‘opsis‘ meaning ‘alike’.

These poppies were once considered a myth, due to the unusual blue colour of their flowers. Research into how this colour is created has been conducted and the pigment has also been produced artificially. The chemists among you may have already guessed which important chemical is behind it.

A cocktail of chemicals, including metal ions iron (Fe3+) and magnesium (Mg2+), along with anthocyanin and flavonol can be mixed together, to artificially produce a pigment matching the iconic sky blue colour of Himalayan Poppies. Iron is also responsible for the blue in Prussian Blue pigments, the first modern, synthetic pigment.

Purple Lupins

I took this photo last December, when I travelled to New Zealand for the first time. The Lupin genus (Lupinus sp.) is a member of the pea family (Fabaceae) and includes over 200 species. Where they’re native in the Americas, they’ve served as an important crop food for centuries. Unfortunately in New Zealand, these lupins (Russell Lupin – Lupinus polyphyllus) are high invasive and threaten local ecology.

An invasive species is a species that has been introduced from its native region and has become problematic. In the UK, we have several invasive species, including Japanese Knotweed, Himalayan Balsam and Feverfew. Management strategies have to be put in place for these species to prevent them from encroaching on native species.

Like all invasive species, there are both pros and cons to their existence in the wild. Russell Lupins were introduced as sheep feed around Lake Tekapo and now draw in tourism and are a good food source for New Zealand native butterflies. However, they are out-competing native flora so stategies are underway to control their spread.

While I’m not able to celebrate Pride in London this weekend, I’m happy to be able to show my support for the LGBT+ community in my own way. If all plants were grass, the world would be an awfully boring place. Diversity makes the world fun and interesting, and in the words of William Cowper, “Variety is the spice of life”. Happy Pride!


Bottlebrush: Sardaka / CC BY-SA

Strawflower: Vinayaraj / CC BY-SA

Sunflower: Sivahari / CC BY-SA

Sea spurge flower: Sannse at the English language Wikipedia / CC BY-SA

Sea spurge: Zeynel Cebeci / CC BY-SA

Himalayan Poppy: Axel Kristinsson from Reykjavík, Iceland / CC BY


Bottlebrush Tree: Eat The Weeds

Bush Food: Wariapendi Nursery

Heliotropism: Plant Life

How sunflowers track the sun: Phys

Sea Spurge: The Wildlife Trusts

Sea Spurge: Herbiguide

Ferric ions involved in the flower color development of the Himalayan blue poppy, Meconopsis grandis

Himalayan Blue Poppy Or Tibetan Blue Poppy: SnaPlant

War of the lupins: New Zealand Geographic


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