{"id":28268,"date":"2023-06-01T15:29:22","date_gmt":"2023-06-01T13:29:22","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcwildlife\/?post_type=purple_issue&p=28268"},"modified":"2023-06-01T18:28:36","modified_gmt":"2023-06-01T16:28:36","slug":"love-is-in-the-air-2","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/2023\/06\/01\/love-is-in-the-air-2\/","title":{"rendered":"Love is in the air"},"content":{"rendered":"\n

Love is in the air<\/h2>\n\n

POLLINATION <\/strong><\/h5>\n\n

The natural world as we know it wouldn\u2019t exist without pollination. We delve into the cool science of plant sex.<\/span> <\/span><\/strong><\/p>\n\n

By <\/em>LEIF BERSWEDEN <\/strong><\/p>\n\n

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Hazel catkins broadcast pollen on the wind, with no need for pollinating insects <\/figcaption><\/figure>\n\n

PLANTS, IN ALL their charismatic forms, are most famous \u2013 and most celebrated \u2013 for their flowers. Eight in ten species have them, and they come in all shapes and sizes. Cowslips and honeysuckles are equipped with trumpet-like, tubular flowers, while thistles have punky, purple flowerheads made up of lots of tiny blooms. There are miniature, corn-on-the-cob eelgrass flowers, water-lily flowers the size of your fist, and orchid flowers that mimic insects. <\/p>\n\n

Why all this diversity? Well, you see, a plant has needs. <\/p>\n\n

When mating season comes around, flowering plants engage in all the same behaviours as we do. They spruce themselves up, paying attention to how they look, how they smell and how they dress. And then, when they\u2019re ready, they flirt. To walk through a hay meadow in June is to witness plants unashamedly getting their groove on. Just like in a nightclub, the air is full of perfume and there\u2019s eyeing-up-and-down occurring everywhere you look. <\/p>\n\n

But here\u2019s where things are slightly different. Flowering plants aren\u2019t trying to seduce each other. Not directly, at least. For millions of years, conifer-like, seed-producing plants used airborne pollen (generated by the male parts) to fertilise each other, but female reproductive surfaces are small, and a lot of it went to waste. Plants needed a more targeted courier service for collecting and delivering pollen, something more precise and economical than random gusts of wind. So they evolved flowers to attract insects (and later, other animals, such as birds and bats). Today, flowers are used by 80 per cent of plants to reproduce.<\/span><\/p>\n\n

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A mining bee drops pollen <\/figcaption><\/figure><\/div>\n\n

The process by which that happens \u2013 pollination \u2013 is quite literally plant sex. The premise is simple. A typical flower has two sets of reproductive parts: a female stigma and multiple male stamens. Pollen is transferred from the stamens of one plant to the stigma of another, fertilising the flower and initiating seed production (see diagram <\/em>on <\/em>the <\/em>opposite <\/em>page). <\/em>It\u2019s an elegant system that has been one of life\u2019s greatest success stories. But how that pollen is transferred \u2013 well \u2013 that\u2019s where it gets really interesting. <\/p>\n\n

ANIMAL POLLINATION is a dance; a complex conversation between plant and pollinator. Plants and insects have evolved side by side for millions of years. Most plants offer insects a reward \u2013 usually in the form of sugary nectar to slurp \u2013 in exchange for visiting their flowers. But insects are spoilt for choice. On any given day, there can be thousands of flowering plants clamouring for their attention. Plants need to entice them; to persuade them into drinking their nectar. This is where the flirting comes in. <\/p>\n\n

About 80 per cent of Britain\u2019s flowering plants are pollinated by insects. They include at least 1,500 species of butterfly, moth, bee, fly, wasp, and beetle \u2013 remarkably, about 1,000 species of UK beetles are pollinators. The flowering plants have opted for many different strategies to attract suitors. Some developed shine and gloss, others a palette of bright colours, and some just became smelly. Life for an insect-pollinated plant is all about curating their package and fine-tuning the details, either to attract specific pollinator species or to stand out from the crowd. <\/p>\n\n

Scent is one of the most important means plants have of communicating with insects as it\u2019s often the first point of contact between plant and pollinator. Just like the perfumes for sale in a department store, floral scent is a cocktail of chemical compounds that evaporate and move through the air, leaving a trail of invisible breadcrumbs leading back to the flower. Plants have spent millennia experimenting with species-specific blends and mixtures of scent compounds. Through trial and error they have refined their scent so that it\u2019s unique to their species. <\/p>\n\n

What a flower smells like depends entirely on what it\u2019s trying to attract. Sweetsmelling flowers might be enticing bees, for example, while musky blooms are more attractive to beetles. One of my favourites is a common woodland plant called lords-andladies (as featured in this year\u2019s BBC series, <\/span>Wild <\/em>Isles), <\/em>which attracts little flies by marketing itself as warm, rotting meat (see <\/span>box <\/em>above).<\/em><\/p>\n\n

So, smelling nice \u2013 or not so nice \u2013 is one way to get some \u2018alone time\u2019 with your pollinator. Looking sexy is another. Most flowering plants use visual cues to attract visitors and this involves making their flowers as eye-catching as possible. But while we can all fawn over the beauty of a flower or marvel at its shapes and colours, these attributes are \u2013 quite literally \u2013 not meant for our eyes. This is very clear in nocturnal species such as night-flowering catchfly (Silene <\/em><\/span>noctiflora). <\/em>Built to attract night-flying moths, it only blooms in the dark.<\/span><\/p>\n\n

\u201cMany flowers are decorated with hidden patterns written in botanical invisible ink\u201d <\/strong><\/p><\/blockquote>\n\n

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Cheats of the plant world, early spiderorchids mimic female bees to attract males <\/figcaption><\/figure><\/div>\n\n

ANOTHER GOOD EXAMPLE IS plants\u2019 use of ultraviolet pigment. Many flowers are decorated with hidden patterns written in botanical invisible ink. A buttercup, for example, might just look bright yellow to you and me, but to a bee \u2013 which can observe the ultraviolet spectrum \u2013 it has a large black splodge in the centre. Plants use these hidden patterns to direct visiting insects to the nectar \u2013 and in doing so make sure they come into contact with their all-important reproductive parts. <\/p>\n\n

Some species have taken this one step further, too, changing colour to communicate with their pollinators. Forget-me-nots \u2013 those dainty flowers with five sky-blue petals surrounding a yellow ring \u2013 colour-code their blooms. Once a flower has been pollinated, the yellow ring at its centre (which to an insect appears black) fades to white, signalling to visitors that there\u2019s no more nectar and directing them towards as-yet unpollinated blooms.<\/span><\/p>\n\n

\"\"<\/figure><\/div>\n\n
\"\"
Marine eelgrasses release pollen grains into the water <\/figcaption><\/figure><\/div>\n\n
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Night-flowering catchfly blooms only in the dark <\/figcaption><\/figure><\/div>\n\n
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Male holly grows separately from female holly <\/figcaption><\/figure><\/div>\n\n
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Buttercups have a black splodge \u2013 if you have bee vision <\/figcaption><\/figure><\/div>\n\n

But as in any system that involves cooperation between individuals, it\u2019s only a matter of time before the cheats arrive. In the world of pollination, none are more spectacular than the insect-mimicking orchids. The flowers of the early spiderorchid are uncannily insect-like. While most plants entice pollinators by offering nectar, these orchids lure them in with the promise of bee sex. The early spider-orchid has finetuned itself over evolutionary time to mimic the appearance, scent and even the furriness of the female buffish mining bee. In other words, to the male, the flower looks, smells and feels like a female bee. In attempting to mate with the flower, the male bee unwittingly picks up two tiny, sticky pollen sacs that he then transports to the next orchid. It\u2019s an extraordinary fraud, entirely masterminded by a plant. <\/p>\n\n

INSECT POLLINATORS MAY OFFER THEIR clients a direct courier service, but there are many groups of flowering plants that do things differently. Marine eelgrasses release thousands of tiny pollen grains into the water column in the hope that some will find a female flower. Other species \u2013 among them a buttercup called lesser spearwort \u2013 have developed ways to use rain to pollinate their flowers when wet weather means visits from insects are sparse.<\/span><\/p>\n\n

It would also be remiss to write about pollination without revisiting that age-old go-between from times gone by: wind. Flowering plants have reverted to wind pollination on numerous occasions, much to the annoyance of those who suffer from hay fever. Wind, after all, is considerably more reliable in the long term than vulnerable animal populations. And the savings are immense: with it being no longer necessary to attract insects, there\u2019s no need to produce energy-rich nectar, scent compounds, coloured pigments or high-protein pollen. <\/p>\n\n

<\/div>
\n

Flower in focus: Foxglove <\/strong><\/h4>\n\n\n\n
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Pollinated stigmas with younger male flowers above <\/figcaption><\/figure>\n\n\n\n

Foxgloves have a clever way of avoiding self-pollination and ensuring cross-pollination between different plants. They flower in sequence from bottom to top, with visiting bees working their way up. As they\u2019re pollinated, foxglove flowers change sex from male (with pollen-bearing stamens) to female (with pollen-receiving stigmas). When a bee first flies to the older female flowers at the base of the stem, it will deposit pollen from another plant, gradually working its way up until it reaches the younger male flowers. Here, it will pick up fresh pollen to take to a new plant, repeating the process all over again. <\/p>\n<\/div><\/section>\n\n

Today, about 10 per cent of flowering plant species are pollinated by the wind. <\/p>\n\n

Hazel is one such example. As January rolls into February, a wood-wide network of tiny, anemone-like female flowers is set up to catch wind-blown pollen. Hazel\u2019s male flowers are packed into catkins that dangle like lambs\u2019 tails, shivering at the slightest draught and releasing pollen into the air, which is carried on the breeze to the stigmas of the female flowers, ideally on a hazel some distance away. With no need for insects, they bloom early in the year when woodland foliage is at its thinnest and the wind is free to move through the trees relatively unhindered. <\/p>\n\n

If you\u2019re a flowering plant, ensuring your pollen \u2013 and the genetic material it contains \u2013 is transferred to a different plant is very important to guarantee healthy offspring. Pollinating yourself accidentally is best avoided, so most plants have made efforts to ensure this doesn\u2019t happen. Some species, like holly, go to extreme lengths, separating male and female flowers onto different plants entirely. If you have a holly in the garden that never produces berries, it\u2019s because it\u2019s a male tree. Other plants, such as foxgloves, sync themselves beautifully with the methodical foraging behaviour of bumblebees (see <\/span>box <\/em>above).<\/em><\/p>\n\n

\"\"
The green-flowered helleborine is self-pollinating <\/figcaption><\/figure><\/div>\n\n

\u201cPollinating another individual isn\u2019t always possible and, for some species, just isn\u2019t their cup of tea\u201d <\/p><\/blockquote>\n\n

But pollinating another individual isn\u2019t always possible and, for some species, just isn\u2019t their cup of tea. There are numerous species that forego wind, water and animal pollination altogether, and just get on with the job themselves. The green-flowered helleborine is one of these, often pollinating itself before the flower buds have even opened. <\/p>\n\n

It\u2019s amazing what plants can do and what they get up to. Pollination involves so much more than we might ever have imagined. It\u2019s so exciting to share our home with plants that have gone to such interesting and extraordinary lengths to get some action. They generate heat, hide patterns in invisible ink, communicate with colour changes, and even risk genetic health, all in the name of moving pollen from stamen to stigma. <\/p>\n\n

TO HUMANS, JUST AS IT IS TO plants, pollination is everything. In Britain, one third of our food crops are pollinated by insects. Honeybees account for between 5-15 per cent of them, while the other 85-95 per cent are made up of wild insects such as solitary mining and mason bees, wasps and flies. <\/p>\n\n

Our flying insects are in deep trouble, though. As many as 60 per cent of them have disappeared in the past 20 years. <\/p>\n\n

And our plants? Well, pollination is even more important to them than it is to us. For most of the 80 per cent that produce flowers, it\u2019s their entire future. And given their position at the heart of the food web, it\u2019s very much in our interest to prioritise them. Pollination is a process we take for granted. It goes on all around us, often largely or entirely unseen. And it\u2019s one we must protect with everything we have. <\/p>\n\n

<\/div>
\n

Flower in focus: Lords-and-ladies <\/strong><\/strong><\/h4>\n\n\n\n

What goes on inside the lords-and-ladies plant is quite unexpected. These plants have got pollination down to a T. <\/p>\n\n\n\n

Rising from a green, leafy cocoon is a chocolate-brown, phallic organ known as a spadix that \u2013 like a mammal \u2013 is capable of generating heat. Thermalimaging studies have shown that, on the first day of flowering, the temperature of the spadix can climb above 30\u00b0C. Why they do this is not known for certain, but the most likely explanation is to evaporate smelly scent compounds to attract flies. <\/p>\n\n\n\n

These flies crawl into a chamber below the spadix, immediately passing through a mesh of downward pointing hairs that prevent them from leaving. Any pollen that the flies have previously collected gets deposited on the yellow female flowers at the bottom of the chamber. <\/p>\n\n\n\n

Once these have been fertilised, the red male flowers above shed their pollen onto the insects. The hairs at the entrance to the chamber then wither, allowing the freshly coated insects to escape and pollinate another plant. <\/p>\n\n\n\n

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The pollination process hidden inside this woodland plant <\/figcaption><\/figure><\/div>\n<\/div><\/section>\n\n
ABOUT THE AUTHOR<\/span> <\/strong><\/h5>\n\n
\"\"<\/figure><\/div>\n\n

<\/p>\n\n

Leif Bersweden is a botanist and author and runs plant ID courses. His latest book is Where the Wildflowers Grow <\/em>(Hodder & Stoughton, \u00a310.99). Visit leifbersweden.com<\/a>.

<\/p>\n\n

ARTERRA\/GETTY; SOLITARY MINING BEE: PHIL SAVOIE\/NATUREPL.COM; ARUM: RICHARD GRIFFIN\/ALAMY; ORCHID: ROSS HODDINOTT\/NATUREPL.COM; DIAGRAM: ALI DAMOUH\/SCIENCE PHOTO LIBRARY\/GETTY; CATCHFLY: ADRIAN DAVIES\/ALAMY; EELGRASS: SHANE GROSS\/NATUREPL.COM; HOLLY: N NEHRING\/GETTY; BUTTERCUPS: OZGUR KEREM BULUR\/SCIENCE PHOTO LIBRARY\/GETTY; HELLEBORINE: PAUL R. STERRY\/NATURE PHOTOGRAPHERS LTD\/ALAMY; FOXGLOVE: PHIL SAVOIE\/NATUREPL.COM<\/p>\n","protected":false},"excerpt":{"rendered":"

PLANTS, IN ALL their charismatic forms, are most famous \u2013 and most celebrated \u2013 for their flowers. Eight in ten species have them, and they come in all shapes and sizes. Cowslips and honeysuckles are equipped with trumpet-like, tubular flowers, while thistles have punky, purple flowerheads made up of lots of tiny blooms. There are miniature, corn-on-the-cob eelgrass flowers, water-lily flowers the size of your fist, and orchid flowers that mimic insects. <\/p>\n","protected":false},"author":24,"featured_media":28891,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ub_ctt_via":"","purple_page_number":"72","purple_custom_meta_purple_page_number":"72","purple_seq_number":"1","purple_custom_meta_purple_seq_number":"1","purple_source_article":"article_72-1.xml","purple_custom_meta_purple_source_article":"article_72-1.xml","purple_source_issue":"June-2023","purple_custom_meta_purple_source_issue":"June-2023","purple_external_id":"June-2023-72-1","purple_custom_meta_purple_external_id":"June-2023-72-1","purple_issue_code":"|0000087245||","purple_custom_meta_purple_issue_code":"|0000087245||","purple_android_product":"com.im.wildlife.505","purple_custom_meta_purple_android_product":"com.im.wildlife.505","purple_ios_product":"com.im.wildlife.505","purple_custom_meta_purple_ios_product":"com.im.wildlife.505","purple_web_product":"","purple_custom_meta_purple_web_product":"","purple_publication_id":"58d61955-0ac4-406c-83f1-ab6f21d86b70","purple_migrated":"","kt_blocks_editor_width":"","apple_news_api_created_at":"2023-05-30T10:23:47Z","apple_news_article-theme":"","apple_news_api_id":"1549d30e-ebd0-4a30-a7bc-49350bc972b2","apple_news_api_modified_at":"2023-06-01T13:54:43Z","apple_news_api_revision":"AAAAAAAAAAAAAAAAAAAAEw==","apple_news_api_share_url":"https:\/\/apple.news\/AFUnTDuvQSjCnvEk1C8lysg","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":true,"apple_news_is_preview":true,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_article_theme":"","apple_news_sections":"[]"},"categories":[27],"tags":[14],"apple_news_notices":[],"featured_image_src":"https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-scaled.jpg","author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/author\/importmanagerhubsprylab-com\/"},"acf":{"readingTimeMinutes":"11","apple_news_title":""},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-scaled.jpg",2560,1709,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-300x200.jpg",300,200,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-768x513.jpg",768,513,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-1024x684.jpg",800,534,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-1536x1025.jpg",1536,1025,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/44\/2023\/05\/GettyImages-971552290_cmyk._preview-2048x1367.jpg",2048,1367,true]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcwildlife\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"PLANTS, IN ALL their charismatic forms, are most famous \u2013 and most celebrated \u2013 for their flowers. Eight in ten species have them, and they come in all shapes and sizes. Cowslips and honeysuckles are equipped with trumpet-like, tubular flowers, while thistles have punky, purple flowerheads made up of lots of tiny blooms. There are…","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/posts\/28268"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/comments?post=28268"}],"version-history":[{"count":12,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/posts\/28268\/revisions"}],"predecessor-version":[{"id":29087,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/posts\/28268\/revisions\/29087"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/media\/28891"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/media?parent=28268"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/categories?post=28268"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcwildlife\/wp-json\/wp\/v2\/tags?post=28268"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}