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Wild Wild Life Newsletter: Unlocking the secrets of flowering plants

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Darwin hybrid red tulips, primroses

f o g a a s/Tom Meaker/Shutterstock

Hello, and welcome to January’s Wild Wild Life, the monthly newsletter that celebrates the biodiversity of our planet’s animals plants and other organisms. To receive this free, monthly newsletter in your inbox, sign up here.

I spent much of late 2021 and early 2022 looking ahead to what the pandemic has in store for us this year . The continued uncertainty wrought by covid-19 didn’t make me particularly cheerful, at a time of year when I would normally be making plans and looking forward to warmer months. So, it’s time to think smaller, closer, greener: in the absence of any grander schemes, I’m making plans to plant as many different herbs as I can this year, so that I can stop buying those plastic supermarket packets of fresh herbs that always seem to spoil before I’ve used them. I’ve already got chives, basil and thyme, plus two small bay and makrut lime trees. Next, I’m going to try growing lemongrass from seed.

My love of gardening stems from my training as a plant biologist and, this month, I’ve been enjoying delving back into plant science, with some interesting new discoveries about how plants develop and are cultivated. Also in this newsletter, glowing fish, tiny snails and remembering E. O. Wilson.

Understanding plants

I think one of the biggest barriers to developing an interest in botany comes not from the fact that plants don’t move, behave and charm us like animals do, but because there are so very many of them and it’s difficult at first to really grasp how they all differ from or relate to one another. But with some understanding of the various family groups and their anatomic traits, you can quickly come to get a “feel” for most plants you encounter. If you show me a grass plant, I almost certainly won’t be able to tell you what species it is, but I will have a good idea of how and where it lives, and how it flowers and reproduces.

There’s one particular distinction that will help you gain insight into almost all the world’s flowering plants: whether a seed germinates with a single or pair of starter leaves, known as cotyledons. A plant’s seed leaves are thrilling indeed – a sign that you’ve successfully coaxed life from a dormant embryo. When I see this first sign of life, I can immediately tell a lot about a plant, starting with whether it is a monocot (one seed leaf) or a eudicot (two).

The vast majority of the world’s plants are flowering plants, and of these, 97 per cent of species are either a eudicot or monocot. It’s a distinction that has been made since the 17th century, and it goes well beyond a plant’s first leaves. If you look at plants that germinate with a single cotyledon, you are likely to see parallel leaf veins on their subsequent leaves and, should you have an electron microscope to hand, a single pore in their pollen grains. Another clue is that their flowering parts are usually multiples of three – for example, a tulip (pictured above left) has three petals, six stamens (the male parts) and a stigma (female part) with three lobes. Plants with two cotyledons tend to have net-like veins, three pores in their pollen grains, and their flowers are organised on multiples of four or five. An example are primroses (pictured above right), with their five petals. As a botanist, you learn not to be shy about getting close to a plant’s flowers and leaves and giving them a good inspection, counting and describing their anatomy, ideally with the help of a hand lens.

What’s pleasing about the distinction between monocots and eudicots is that it was based on studying plant anatomy, was then thrown up in the air by the genetic revolution of the past century, but has now landed back in roughly the same place as before. The genetic evidence supports these two major groups, but suggests around 3 per cent of species, including magnolias and water lilies, don’t belong in either. These analyses led to a slight name change – originally known as the dicotyledonous plants, the newer eudicot name reflects the slight tweaking of the group that was informed by genetic evidence.

We know the most about eudicots, partly because this group contains three-quarters of all flowering plants (while 22 per cent are monocots), but also because the most-studied plant on Earth is Arabidopsis thaliana , a pretty simple eudicot weed that’s easy to grow and study. One challenge is applying the vast insights we’ve gained from eudicots to their monocot cousins. For example, we know a lot about how eudicot leaves develop, but how does that relate to the very different blades of the grasses, a large group within the monocots?

That’s one question that now seems to have been solved. One hypothesis has been that blades of grass mostly form from the same type of tissue that forms petioles in eudicots (petioles are the stem-like bit at the base of a leaf). This was based on the fact that eudicot petioles have parallel veins, just like the leaves of monocots.

But a new study suggests that an alternative, older hypothesis is likely to be the correct one: the blade part of a grass leaf is equivalent to the main leafy bit of eudicot leaves. The team behind the research determined this by combining genetic approaches with computational modelling to uncover how the shape and structure of the leaves of A. thaliana and maize (a monocot) develop. It’s a familiar approach for me, as my doctoral work involved combining genetic approaches with insights from modellers to understand explosive seed dispersal. The researchers liken their finding to an older discovery in animals, when new genetic evidence reinstated the old and discarded idea that the fronts of our bodies are equivalent to the backs of insects, and vice versa.

Another recent monocot breakthrough was finally finding a way to graft these plants. Attaching the shoots of one plant to the roots of another may sound nothing more than a specialist growing technique, but it’s extremely useful for fighting disease in crops that are propagated as clones. Indeed, it may be the breakthrough we need to save both bananas and the agave grown for tequila. These are both monocot plants and, until now, it was thought that their anatomy made them impossible to graft.

This month I learned…

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Deep-sea angler fish

William Ludt/Journal of Fish Biology

…that a species of deep-sea anglerfish can glow in two different ways.  Like plenty of deep-sea fish, the Pacific footballfish (Himantolophus sagamius ) can use symbiotic bioluminescent bacteria to light up its dark home. But we now know that it can also do something called biofluorescence – absorbing one wavelength of bioluminescent light, and then reflecting it as a different colour. This is a rare skill in the deep sea and has never been documented in anglerfish before.

 

Newly described species of the month

Angustopila psammion

Angustopila psammion, the smallest snail ever identified on land.

Contributions to Zoology 2022

Behold Angustopila psammion, the smallest snail ever identified on land. Discovered in cave sediment in Vietnam, its shell is only 0.48 millimetres high and has a volume of just 0.036 cubic millimetres, about a fifth of a typical grain of sand. The snail probably doesn’t live in caves though – the researchers who’ve described it think it is likely to live in limestone crevices or on plant roots.

 

Archive deep dive

American biologist E.O. Wilson

E.O. Wilson

GRETCHEN ERTL/REUTERS/Alamy

The remarkable naturalist E. O. Wilson died on 26 December and it’s well worth exploring his incredible lifetime’s work. As well as being the pre-eminent expert on ants, Wilson demonstrated the evolutionary basis of social societies, explaining altruism and arguing the controversial position that selection can act on groups, not just individuals or their genes. He was an outstanding advocate for conservation and preserving our planet’s biodiversity too. When I met him back in 2015 , I asked him if, after all he had achieved, there was anything else he would liked to have done. His answer wasn’t anything trivial: he would have loved to have discovered the structure of DNA.

 

Other wildlife news

  • The kunga may have been the first hybrid animal bred by humans.

Your long read this month is this intriguing feature by my colleague Chelsea Whyte about the mysterious cat-like animals that lived in North America 23 million years ago and then vanished. I have also been dipping into a new guide to the wildlife of Japan . It explores not just the animals of the country’s islands, but also the regions and the best seasons to see them – perfect for armchair travelling. I have, of course, been watching new BBC documentary series The Green Planet, and I’ve also enjoyed hearing about how Masanobu Fukuoka pioneered the idea of “do nothing” farming in mid-century Japan on the podcast Outside/In.

Do let me know how animals and plants have been helping you get through this start to the new year at wildwildlife@newscientist.com or tweet me your pictures @PennySarchet. I’ll be back next month.

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