Sunday, 31 August 2014

Parts of a simple flower

The photograph below shows the flower of a Japanese anemone. 



The next photo shows a close-up of the reproductive parts of the same flower. 



The Japanese anemone makes simple flowers (as opposed to composite flowers, which we'll think about another time).

A simple flower has sexual organs in the middle of the flower, and petals or bracts round the outside edge. The female organs are in the centre and the male organs are in a ring around the female organs. When it's time for pollination to happen, pollen from the male organs is taken by insects, the wind, or other vectors, and lands on the female organs of the same or a different flower.


Glyphosate



Glyphosate is a chemical that we hear a lot about these days, but what does it actually do to plants? 

The bramble leaf below has been treated with glyphosate and shows the usual pattern of loss of chlorophyll from the leaf, with only the leaf veins retaining the chlorophyll. 




For comparison, the leaf below was left untreated and the chlorophyll levels are uniform across the whole leaf. 



Why does glyphosate produce this pattern of pigment loss?


According to the Wikipedia, "Glyphosate's mode of action is to inhibit an enzyme involved in the synthesis of the aromatic amino acids tyrosinetryptophan and phenylalanine.". 


I've been trying to figure out why the loss of these amino acids specifically leads to the loss of chlorophyll but the information is not leaping out at me. Possibly it just stops the plant from being able to make most compounds. As chlorophyll needs frequent repair and replacement, and because it's absence is very obvious, the loss of chlorophyll may just be the thing that we see first. I haven't been able to find confirmation of this online. Mysterious! I will keep looking. 



Saturday, 30 August 2014

Guess what it's going to be!



One of the most satisfying activities in botany is looking at a plant in bud and imagining when the bud will burst, how fast the growth will occur, and what the final structure will look like. It's like opening a parcel at Christmas - the anticipation just as good as the end result. 

The photo below shows a developing flower of Scabiousa 'Butterfly Blue'. The flower head currently seems to be a flat plate covered in tiny balls of green dough. Just by looking at these tiny structures there is no way to know what they would grow into. In a garden environment, no one really knows when the growth will happen, as it is entirely dependent on temperature. Plants grow much faster at 22 degrees Celcius than at 15 degrees, and so it's really all down to the weather. 



If you would like to see the final form of the flower enjoy a little google image search on "Scabious 'butterfly blue'" or have a look at the photo on the Missouri Botanical Garden website. There are some truly stunning close-ups out there and the vibrant blue is quite surprising when we know that those petals were just little green balls of dough a few days earlier. 

Next time you are out walking, have a look at some of the buds that you see in your neighbourhood and try to guess what they will become. Watch for the seasons changing, and the warm temperature that brings about their transformation. Plant grow quickly, but not so quickly that you cannot see their growth unfold over the course of a few days. See if you can catch them at it!







Thursday, 28 August 2014

Spontaneous Verbena bonariensis mutation



Earlier this year I grew some Verbena bonariensis plants from a free packet of seed that dropped out of a magazine. The seed grew very well but the plants have turned out to be an interesting mutated form of the more usual herbaceous border favourite.

To see the usual form of the plant have a look at the Wikipedia photo. As you can see the stems produce a large flat head with many many tiny pink flowers. The two photos below show one of these flat heads from the side and the top. 


Verbena bonariensis - the herbaceous border favourite.
The reproductive structures seen from the side. 

Verbena bonariensis - the herbaceous border favourite.
Reproductive structure seen from above. 

So much for the normal form. Now to this interesting mutant form. There are a couple of photo below showing the reproductive structures from the side.

Verbena bonariensis; un-named mutant form. Reproductive structure seen the from the side. 

Verbena bonariensis; un-named mutant form. Reproductive structure seen the from the side. 

So what's going on with these mutant plants? It seems to me that usual form of the plant produces a large flowering shoot, with a cluster of many short inflorescences at the top. Each inflorescence terminates in a large number of small flowers. (I'm tempted to give an analogy for the newcomer here, but fear that I would be toasted for over-simplifying the subject into nonsense.)

The mutant form, by contrast, has a flowering shoot that carries a smaller number of long inflorescences. Each inflorescence terminates in a smaller number of rather small flowers. 

This mutation seems to correspond, to some extent, with the floricaula mutant of Antirrhinum majus, which produces many inflorescences, but never makes the transition to producing actual flowers.

The floricaula mutant of Antirrhinum majus


This image shows the floricaula mutant and wild type forms of Antirrhinum majus

This image comes from the work of Enrico Coen and Rosemary Carpenter
at the John Innes Centre in Norwich.
 It shows the floricaula and wild type forms of Antirrhinum majus.
(The image comes from http://rico-coen.jic.ac.uk/index.php/File:Flo2s400.jpg)

The floricaula mutant plants are very conspicuously different from wild type when viewed from the side. The wild type plants produce large showy flowers, but in the place of these flowers the floricaula mutants produce only green inflorescences, with no flowers at all. 


Back to Verbena...


So does the Verbena bonariensis show a floricaula-type mutation? Well I don't know, and neither will anyone else, because no one funds this kind of research. Isn't it fun to wonder about it though? 

Keep wondering, all you itinerant botanists!