Wednesday, 30 December 2009

Plants in the Mist


You learn a lot about a plant when you grow it in your garden. You can read all you like in books and on the internet but only when you watch it day by day do you get to really know the plant.

I’ve just discovered the flowers of a coffee bush all open within the same day or two. On Boxing Day (see previous blog) I excitedly photographed the first flower, the next day there were are all open, up and down every stem.

There is at least a second flush on the way (in bud) but the plant seems to like mass flowering. The flowers were also very short lived, opening for only 24-48 hours, with the female receptive stalk (the style) remaining after the petals and the male bits were all brown and shrivelled.

I’m sure I could find that out somewhere in the botanical literature, but I wouldn’t have thought to look. It’s a bit like trying to piece together how gorillas live without someone like Dian Fossey living amongst them for a while. You need to wake up each morning and see what they are up to – gorilla or plant.

You hear plant scientists, botanists, saying all the time they need to study plants in the field or grow them in a glasshouse. Although collections of dried plants (herbaria) are essential for studying the variation over time and space – you just can’t go out and observe enough different plants in different places – seeing the plant grow makes all the difference.

Most of my botanical research has been on algae rather than flowering plants, but the same thing applies. During my PhD I would collect my algal subjects (in this case a thread-like alga called Vaucheria that formed green, felty mats on soil, in streams or in saltmarshes and muddy tidal areas).

I would pick out a few threads and grow them on a jelly-like substance (agar – an algal product incidently) in the laboratory and watch them grow and reproduce. That way I understood subtleties in their biology and could investigate whether individuals that looked different were perhaps just responding to different environmental conditions.

Anyway, it gave me great insights into Vaucheria and helped me identify and classify them. I haven't cultured many of the algae I've studied since and I'm sure I misinterpret features and differences because of this.

So now that I have a coffee bush in flower I can watch the flowers turn into fruits and probably find out a lot more about my favourite food plant (I elevate coffee to the level of an essential food).

Also flowering for the first time in my garden this year is that well known and beautiful Sydney garden plant, the frangipani (Plumeria). We planted two of them three years ago – about the same time as the coffee bush – and they are two are doing their thing over Christmas. In this case it’s a bunch of deep pink and white flowers, opening one or a couple at a time. Each flower also hangs around for a week at least.

So the frangipani has a quite different strategy to the coffee bush which goes for broke and exposes its flowers to willing pollinators all in one hit and quickly. Presumably the big showy franipani is easy to spot by a passing pollinator while the coffee bush needs a mass flowering to attract its pollinators. That said, the frangipani usually has lots of flowers open and visible on a larger plant. Maybe the coffee bush is syncronised with some kind of peak in insect numbers. Maybe...

I'm a mere amateur at this garden observing though. I recently skimmed through a book called 'Seed to Seed: the Secret Life of Plants', published in 2006 by biologist (although the author isn’t entirely satisfied with that term) Nicholas Harberd. It's all about a year in the life of a plant, in this case Arabidopsis thaliana, or Thale Cress, the botanist’s answer to the fruit-fly (I've written two blogs on examples of this role).

In fact the book is more than that – it is much about the DNA, hormones and life history of plants as it is about a tough year for a poor little rabbit-munched Thale Cress. I was looking for evidence of seasonal changes, and support or otherwise for my seasonal classification. Let me just say that it confirmed my suspicion that things are different in Australia.

I haven't come close to observing a plant for as long as Nicholas Harberd but already I'm learning things. I had already noticed of course that frangipanis opened sequentially but I hadn’t thought much of it. The coffee bush is new to me.

There is so much fascinating biology and evolution behind the simple difference between these two plants in flower in my garden. I can’t wait to see what happens next.

Images: the top image is the frangipani in my garden and the middle image the coffee bush flowers now all open together.

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