by Piter Kehoma Boll
Everybody likes flowers, right? They are so colorful and beautiful and usually have a wonderful scent. People love to have them in their gardens and women love to receive a nice flower bouquet from their boyfriends.
Some flowering plants, from left to right: Rosa ‘Hybrid Tea’, Pachystachys lutea and Zinnia elegans. All photos by Piter K. Boll (i.e. myself!)*
But why are flowers so beautiful? Of course the flowers seen above are derived from varieties artificially selected by humans to increase their beauty, but flowers in nature are wonderful too!
Naturally occuring flowers. From left to right: Oxalis sp., Ipomoea fimbriosepala and Zephyranthes robusta. All photos again by myself (Piter K. Boll)*
Surely that beauty is not intended to please people or whatever. That’s totally nonsense and just some religious people could have such a wrong idea. If plants have nice flowers, it must give them some advantage.
As everybody knows (at least I hope so), plants usually cannot move like animals, so they are condemned to stay still on their spot. That can mean a lot of trouble when you are looking for resources like water, light or basic elements like nitrogen. So evolution leads to the rising of amazing structures to make plants survive, like getting a hard stem to become taller or developing smaller or larger leaves, thorns, tendrils or even becoming carnivorous. But plants also need to reproduce and for that they need a mate, but since they are attached to the substrate, they have to find alternative ways to join their gametes.
Most primitive plants manage to do that through water or wind, just letting their reproductive structures go and hoping that they will reach their destination. As you can see, this method is not the best one, since fertilization occurs totally by chance. Besides that, these ways are limited regarding to the places where they are successful. A plant fertilized through water needs to be inside water or live close to the ground on places where it eventually get submersed; the same way, a plant which relies on the winds needs, of course, to be where the wind blows.
Moss (left) relies on water to reproduce, while conifers (right) need wind. Once more, photos by Piter K. Boll. *
Those methods, though limited, worked well enough for millions of years until sometime in the Cretaceous period, when a group of animals started to diverse astonishingly: the insects.
Insects are small and prolific. They have a hard outer skeleton of chitin, which prevents dehydration and injuries, and many of them learned to fly, so being able to cross large distances and colonize new habitats.
Insects existed, of course, at least since the Carboniferous. The most famous of them is the giant dragonfly Meganeura. But during the Cretaceous those groups that today are the most diverse started to appear in fossils: ants, bees, termites, butterflies, moths, aphids and grasshoppers. Beetles, the most diverse group of insects today (containing more species than all other arthropods together) are found in fossils since the Carboniferous, but almost went extinct during the Permian-Triassic boundary that marks the most terrible mass extinction on Earth. After this tragic event, they stayed more discrete until a boom in diversification in Cretaceous together with the already mentioned insects.
Well, all those insects needed to eat like anything else and started to feed on plants, including their pollen. That could have been a serious trouble, but plants managed to deal with it by modifying themselves in a way that the insects now became something useful to them. If insects were attracted to their pollen, why couldn’t they carry it to other plants, so assuring a more secure fertilization?
That’s exactly what plants made, but in order to attract insects even more to their reproductive organs, those started to increase in size and get nice colors. It all happened through natural selection of random mutations, of course. No one is assuming that plants or insects actually chose to change, that’s nonsense. What I’m trying to say (through a simpler way) is that those plants that were able to attach some of their pollen grains to insects, so that it reached other plants that the insect visited, were more successful to reproduce. The same way, those plants with more beautiful flowers attracted more insects and were also more successful to reproduce.
Anyway, that’s why we should thank insects for existing, since without them we wouldn’t have so nice flowers to decorate our lives. And if you like flowers but hate insects, well, you are being extremely unfair to nature.
I know that some may say “but I like butterflies. They are beautiful and cool and cute and they pollinate everything, so I just need to like these insects and not all those disgusting things.”
Oh, really? So you like butterflies? I’m sure you like this one:
Caterpillar of Agraulis vanillae. Photo by Bill Frank extracted from jaxshells.org
Most people like butterflies and hate caterpillars, but they are exactly the same thing. And actually these insects spend most of their life as a larva. Now just to satiate your curiosity, this is what that caterpillar looks like as an adult:
An adult of Agraulis vanillae on a head of Zinnia elegans. Photo by Piter K. Boll.*
But butterflies are not the only pollinators and not even the most common ones. Bees, as you know, are also very important and the main pollinators of many economically important plants, especially fructiferous ones. Wasps, flies, mosquitos, scorpionflies and moths are also important, but we cannot forget beetles.
Most basal and primitive angiosperms are pollinated by beetles, so that its more likely that these were the guys behind the appearance and diversification of flowering plants. There are many evidences for that, like an increasing diversity of angiosperms in fossil records being contemporaneous to an increase of beetle species.
Recently, some fossil flowers from the Turonian age (about 90 million years old) were found in Sayreville, New Jersey. Those were called Microvictoria svitkoana due to their astonishing similarity to the giant Amazon water lily, Victoria amazonica, even though much smaller in size.
Flower of Victoria amazonica, one of the most primitive angiosperms. It’s easy to notice that it still resembles somewhat a conifer cone. Photo by Frank Wouters, extracted from commons.wikimedia.org.
Despite primitive, it’s certainly a very beautiful flower, and it can only exist thanks to beetles of the genus Cyclocephala, like this one.
Cyclocephala hardyi, a beetle that pollinates Victoria amazonica. Photo extracted from ssaft.com/Blog/dotclear/
What do you think about it? It’s actually a cool pal, isn’t it? If you look closer, you may see that every insect is amazing in it own way, even cockroaches!
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Béthoux, O. 2009. The Earliest Beetle Identified. Journal of Paleontology, 83 (6), 931-937 DOI: 10.1666/08-158.1
Crepet, W. L. 1996. Timing in the evolution of derived floral characters: Upper Cretaceous (Turonian) taxa with tricolpate and tricolpate-derived pollen. Review of Palaeobotany and Palynology, 90, 339-359 DOI: 10.1016/0034-6667(95)00091-7
Gandolfo, M. A., Nixon, K. C. and Crepet, W. L. 2004. Cretaceous flowers of Nymphaeaceae and implications for complex insect entrapment pollination mechanisms in early Angiosperms. PNAS, 101 (21), 8056-8060 DOI: 10.1073/pnas.0402473101
Seymour, R. S. and Matthews, P. G. D. 2006. The Role of Thermogenesis in the Pollination Biology of the Amazon Waterlily Victoria amazonica. Annals of Botany, 98 (6), 1129-1135 DOI: 10.1093/aob/mcl201
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