Orchids and myco-symbionts

I was fortunate enough to visit Kew Orchid Festival at the weekend.  So many beautiful colours on display.  But the thing that fascinates me most about orchids is their aerial roots.

Aerial roots are typical of epiphytes; plants that don't grow in soil but grow on the branches of trees high above the ground.  Aerial roots are primarily for absorbing water vapour from the air.

However some years ago, the scientists at Kew found something interesting. Try as they might, they couldn't get orchids to grow.  Until they discovered the symbiotic relationship Orchids have with fungi.  Fungi are heterotrophic (breakdown organic molecules) and they provide orchids with essential nutrients.  So now the key to orchid growing success has been solved; just add fungus!

Fern fronds

Fabulous Ferns are next in my series on succession.  They are shown here establishing themselves on moss, which you'll remember outcompeted lichen, the initial colonisers of bare rock. Ferns are a step up from moss, in that they are vascularised plants, ie have vessels for water, and therefore require a slightly thicker soil in which to establish their roots.  The moss traps dust and decaying matter to provide a suitable soil.  Ferns may be a step up from moss but they are still pretty ancient species, as given away by their reproductive lifecycle in which they produce fertile spores on their leaves. No flowering and seed formation for them.  But fabulous fronds that uncurl like a party kazoo more than make up for it.

Marsupial lions?!

Australia's marsupial lions 'dropped from trees' to attack prey, study finds http://gu.com/p/4gndf?CMP=Share_AndroidApp_Blogger

Miraculous moss

Moss is clever stuff.  It doesn't have proper roots and can anchor itself in a very thin soil.  Therefore, it is an early coloniser of bare rock, when just an accumulation of dust as caught here by some twigs provides a sufficient purchase.  Moss itself grows several cm high ( depending on species) and most significantly, traps water and decaying matter. This changes the microclimate, making it less harsh and more suitable for the succession of other species.  Moss is eventually outcompeted.
Interestingly, it is not a flowering plant producing seeds, but reproduces by spore formation.

Early Spring Flowers - indicators of Ancient Woodland

The Hellebores are out in the garden.  Always a welcome sight, growing strongly with large green palmate leaves and beautiful hanging flowers like paper lanterns in pink and white.  I even have some unusual green flowered ones.
These plants have their origins as woodland species.  They come up early, before the leaves on the trees above emerge, blocking out the light. They are adapted to growing in low light levels, in relatively nutrient poor soils, but with the microclimate stability of temperature and humidity provided by the trees themselves.
And they contrast beautifully with their soul mates, the Snowdrops.

Salmon Gill Dissection

Huge salmon heads reveal the gill filaments very nicely.  With their lamellae,  lots of surface area for diffusion of gases.

Note the rakers on the gill arch to prevent food passing over the gills.

Coots continued

Close-up of the flaps on the coot's feet