What is it with flowers? Why are they are red or blue or yellow or pink or a combination thereof? Some smell like honey or fruit salad while others stink bad enough to make you wretch – what’s all that about? And why are some flowers sticky, or hidden away from sight or boldly lined like an airport’s runway? Enough questions! Let The Fynbos Guy open up their secrets.
A flower has one purpose: to allow the plant to reproduce. It’s plant sex, basically. Pollen is transferred from the male part of a flower (stamen) to the female part (ovule) whereupon a fruit develops containing seeds ready for dispersal. Some plants have both male and female parts on the same flower; others separate into male and female plants.
So far so good but now for the tricky part: transferring the pollen. Plants, you may have noticed, don’t move around much from where they are growing. Meeting new plants is a problem for them. Thus they rely on various agents to do the dirty work for them – the pollinators.
Getting it for Free – the Wind
If you are after the cheapest pollinator, you can’t beat the wind – especially here in Cape Town where one day in five during summer is gale-force. Wind is free so wind-pollinated plants generally have small, densely packed flowers without colour or smell as there’s no need to attract anything. But wind pollination is inaccurate and messy so these plants stay close together – the thick stands of Cape reeds (restios) are a good example – and explode with clouds of pollen when disturbed, a crude ‘throw it all at them’ strategy.
Buzz & Hum – the Insects
Everyone knows the role of bees and butterflies as pollinators but fynbos plants are also attended to by long-tongued flies, monkey beetles and earwigs.
Generally speaking, insects don’t do colour very much (bright red appears dark grey to a honeybee) but they are attracted instead to tone: the lighter the better, and often helpfully marked with bold lines to show the way. And since most insects love a smell, the flowers that attract them are not only usually light in colour (white, pink, yellow, pale blue) but also have some kind of scent. Honey for honeybees, rotting meat for carrion flies – plants aren’t too concerned about our own ideas about what a flower should smell like.
At times, the flower-insect relationship is a strange one. The Red Disa, perhaps the most famous of fynbos flowers after the King Protea, is only pollinated by the Table Mountain Beauty butterfly, an insect unusually attracted to the colour red. Some members of the Gentian family are ‘buzz-pollinated’ – the protruding anthers are bundled up and embraced by a carpenter bee which then vibrates its wings for a few seconds to effect pollination.
Cheep Workers – the Birds
Birds are rather like us in that they have a poorly developed sense of smell but are somewhat obsessed by the colour red. Put your nose up against a dazzling scarlet iris or lava-coloured pincushion protea on Table Mountain and you won’t smell a thing but chances are you’ll have disturbed a sunbird or sugarbird. And such flowers reward their feathered pollinators not just with deep reservoirs of nectar but also the countless insects and spiders that are also attracted to the feast.
Sometimes it’s easy to see which bird the plant is aiming at. The long, tubular flowers of many heather (Erica) species are tailor-made for the curved beak of a sunbird – Africa’s equivalent of the humming bird. You’ll also find that many such bird-pollinated flowers are sticky to the touch. This is the floral equivalent of burglar bars – keeping unwanted insects out of the flower or preventing them from biting through the base of the flower to raid the nectar reserves.
Pollinating birds are also the reason we have such extravagant displays of flowers in winter. Many of the Cape’s fynbos-based birds breed in the mild and wet winter months to avoid nesting in the summer fire season. Plants – especially proteas and aloes – respond by flowering at this time, even though there may be snow in the mountains.
Hot-Blooded – the Mammals
If you look closely at your feet when hiking Table Mountain or Lion’s Head, you occasionally spot odd-looking protea flowers hiding low on the ground and under their leaves – in Afrikaans their name translates as ‘shy flowers’. Brown, non-descript and often held face down, it does seem counter-intuitive: why hide from your pollinators? Sniff one of the flowers and you’ll find out why: the pleasantly sweet and yeasty odour is irresistible to rodents.
Mammal pollination of flowers (excluding bats) is extremely rare and it has only been in the last 30 years that scientists have begun to work out what was going on in the fynbos. Some twenty types of ground-hugging proteas and several orchids have their pollen transferred between flowers on the end of a pointy, twitchy nose, courtesy of a striped mouse or rock shrew. There’s no need for the flowers to be colourful as the pollinators are nocturnal but they do need to have an attractive and powerful smell so they can be located in the dark.
Empty Promises – the Victims
Nature is not always so accommodating. Some pollinators are taken for a ride.
There are many flowers in fynbos that rely on trickery, fooling their pollinators into doing the job but granting no nectar reward. The easiest way is to look like a plant that does have nectar: the Cluster Disa (an orchid) is especially good at this and even changes its appearance to resemble different plants in different areas – an Iris on Table Mountain but a red-hot poker (Aloe) in the Langeberg mountains some several hundred kilometres away.
Other orchids have flowers that look like mushrooms, attracting fungus gnats (I’m not making this up) while yet others release a pheromone that tells a certain male wasp or bee that the flower is in fact a female wasp or bee and ready for mating. It’s crude but it works.
Mimicry is a high risk strategy: there’s no need to produce nectar but you have to be good at impersonations or the pollinators won’t be fooled. However, with around a third of the Cape mountain orchids relying on mimicry for pollination, it’s safe to say that they have got it under control.