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Ferns
True or False. The forests that fed and shaded the dinosaurs consisted mainly of plants bearing nuts, seeds, fruits and flowers, and just a few ferns.
Mmm... Seamus? Yes... Michael? Well, um, yes...
I need a bouquet for... someone. And! It has to be really impressive, cool, amaaaazing, like. Like?
Like these? What! But those are just ferns! I want a bunch of something to... um...
impress and amaaaaze... this person. Ferns are amazing, in fact. But they don't even have flowers. Exactly!
They can do everything a flowering plant can do... without flowers! And they've been doing it for much, longer! Amaaaazing! Pteridophytes, commonly known as ferns, are some of the very oldest kinds of plant.
Their early ancestors left fossils dating from the Devonian Period, 360 million years ago! In fact the forests that fed and shaded the dinosaurs were made of ferns. There were no nuts, seeds, fruits, nor flowering plants. Then there were about nine times as many kinds of fern, compared to today. And today, there are still about 12 thousand varieties, - mostly in tropical regions - for example the Tree Fern, which can reach over 20 metres Most modern ferns haven't changed much since they first appeared: 145 million years ago, in the Cretaceous Period.
Okay, dinosaurs were fans of ferns... but... ... There are even more amaaazing things about them! Ferns are vascular plants, which means they have vessels. Like many other kinds of vascular plants, the ferns' roots are covered with - or even penetrated by - specialised kinds of fungus.
The fungi and the roots of the fern grow together. Isn't fungus like, MOULD? Fungus grows on dead things, right? Does the fungus eat the ferns? Or do the ferns eat the fungus?
Nooo. They cooperate! They live in symbiosis. Symbi-what? Symbiotic organisms live together in some way.
In some cases, it is not possible for one to live without the other! Both the fungus and the fern benefit from their cooperation. The fungi and the ferns exchange nutrients from the soil and from sunlight. Both of them benefit. This form of symbiosis is called a mycorrhiza.
In fact, mycorrhizal fungi are very important for healthy plants, soil, and agriculture. More than 90 percent of vascular plants rely on their symbiosis with mycorrhizal fungi. OK... but if ferns don't have flowers... how do they spread? - It's not like dinosaurs pollinate them, right? - NO - some ferns can reproduce by shooting new leaves from the rhizome, or by touching the ends of their leaves to the ground, and sprouting new shoots.
This gives an exact copy, a clone, of the same plant. This is called vegetative reproduction. Ferns are also capable of sexual reproduction. When the genetic information from plants gets shuffled together, it becomes different in the new generation of ferns. Instead of seeds, ferns spread tiny cells like dust in the wind: called spores.
The brown, fuzzy areas on the underside of the leaves are the sori: the fern's spore factories. If a spore lands in a good spot, it'll grow into the next stage in the ferns' lifecycle -- a tiny little leaf, usually less than ten millimeters across. This is called a gametophyte. A gametophyte makes gametes. Some gametes can move - they're the sperm cells.
And some gametes stay still -- they're the egg cells. When a sperm cell makes it to an egg cell, fertilization occurs. Now the part of the fern that we recognise starts to show -- the sporophyte. And the sporophyte makes new spores. And so the cycle continues...
There are many steps in the fern life-cycle compared to flowering, seeding plants -- which have combined the stages of spore, gametophyte, and gamete into the flower. The seed is a fertilized egg ready to grow into a new plant. But, does that mean, like, that the seed plants are more high tech? Are they better? No, they are both here, right?
And if you want a "battle of the plants": think about how much longer the ferns have been around. So, no flowers then... Just these little brown patches ... and those tiny leaves... Symbiosis, mycorrhizal fungi, clones, sori, gametophytes, sporophytes,... ...
Lina will be very impressed and amaaaazed - that you know all about those! - No, she, but... I... I never said they were for Lina!!