Sunday, 18 November 2012

Leaf Collection

There are a lot of leaves in our house. There are a lot of leaves in our car. There are a lot of leaves in Beans' and Bunny's backpacks, because that's what the mesh pockets on the side are apparently for - leaves. A few leaves have even been through the washing machine, which I suppose is better than the rocks and dandelions that went through it all summer.

A little Beans with a lovely oak leaf

We're lucky to live somewhere with a beautiful autumn. People travel from around the world to see fall in central Ontario. Reds, golds, oranges, yellows (yes, it's different than gold) and browns and the hilly landscape gives spectacular views. This fascination with colourful leaves starts early and often manifests itself through obsessive leaf collection. Because you never know when you might see another red leaf quite as pretty as that last one. And of course you then need to glue it to something.

A little Bunny with a lovely oak leaf

You can see the question coming can't you.

Why do the leaves change colour and why are they all different colours?

So leaves start out green because of the chlorophyll, which is what plants use for photosynthesis to make up their food stores. Basically it helps them turn sunlight into sugar. I wish I could turn sunlight into sugar. No, wait, I wish I could turn sunlight into dark chocolate (which I suppose cocoa trees actually do already). There's usually so much chlorophyll you don't see anything else. Leaves also have other pigmented things in them - carotenoids (yellow/orange), tannins (a waste product - brown) and anthocyanins (produced later in the season - red/purple) but there is usually so much chlorophyll that these other colours don't show up. As the days get shorter the plants slow down their food production and the chlorophyll breaks down allowing the other pigments to show through.

Cool fact: A banana turing from green to yellow is the same process - losing chlorophyll to reveal the yellow colour!

The change is triggered primarily by the shortening days. The longer nights mean less sunlight to produce the sugars and slows the chlorphyll production. Leaves are pretty delicate - they wouldn't survive the winter here which is why at these lattitudes they go through the whole process of shutting down and losing their leaves only to grow them again in the spring. A good example of this is if you have your fridge up too high and the lettuce freezes - pretty useless wilty stuff. It's not all for naught though - the leaves decompose providing nutrients into the soil. Nature is pretty good at not wasting. There is some speculation that the anthocyanins in the soil from decomposing leaves will supress plant growth in those areas leading to less competition for the tree the next year. Not bad, nature, not bad at all. And on top of all that the leaves can provide some good habitat too.

The actual colours themselves depend on what and how much of the pigments are in the leaves. The anthocyanins are not produced throughout the year though and are only present in some species and at different levels - which is why they don't all go red and we get the great variation. Yellows and oranges are already present and revealed as chlorophyll lessens. The type of summer and fall weather can have an effect on the production of these pigments as well, which is why some falls have more vibrant colours than others. A dry, sunny fall with temperatures that stay above freezing at night produce brighter colours. Species wise - oaks vary from reds to browns, aspen, poplar and birch go yellow; dogwood goes red. Maples vary - red maple not surprisingly goes bright red and sugar maple a more orangey-red. Sumac goes a lovely fiery red, which is why I plan to plant some next year.

I'm a bit late on this one as the colours have already pretty much finished here for the year, but if you happen to be around here Ontario Parks tracks leaf colour and timing in their parks - Fall Colour Report

So while we do have an abundance of crunchy leaves in the car, it doesn't lessen my love for the fall colours. I've been known to glue a few leaves to stuff myself.


Sunday, 4 November 2012

Fantastic Fall Fruit!

Bunny is a pumpkin fanatic – pie, ice cream, muffins, roasted seeds, jack-o-lanterns...even she’s impressed with their versatility. Beans is currently obsessed with apples, but don’t mess with them – just whole please. This sparked a debate on what was fruit versus vegetable and the realization that what things actually are is not what we call them.

In the botany world pumpkins and apples are both fruits, even though in culinary terms pumpkins and their squashy relatives get called vegetables. This happens a lot – there’s quite a disconnect between what we call things in food related terms versus their actual botanical classification. In the plant world not all fruits are edible, but I would assume that chefs don’t bother classifying inedible things. For example dandelion fluff and maple keys are both fruits.

Fruits, in plant science terms, are the parts of the plant that are formed from the actual flowers and ovaries. Once the flowers are done and pollinated they magically (ok not really, science only seems like magic sometimes) turn into fruits.


Fruits serve a specific purpose – spreading seeds around. That can happen by a variety of methods - floating around (milkweed), sticking to your socks and travelling (burs) or being eaten and carried by various animals and being dropped (or pooped!) elsewhere (apples!). Because of these relationships fruit and animals are dependent on each other – this is a symbiotic relationship (any relationship where we get pie is good in my books).

Beans being symbiotic with an apple

Apples are in the family Rosacae and are a fleshy, simple fruit called a pome. The core is actually the important part to the plant formed from the ovary, the delicious part we eat is just extra tissue from the flower petals and sepals that fuse with the ovary wall that evolved to make us want to eat and disperse.

The ovary forms three parts – the endocarp surrounds the seeds and is hard, the mesocarp is next and is fleshier, the exocarp (not pointed out in these pictures but you can see the line) surrounds that and together they form the core. We eat the hypanthium that surrounds the whole deal, and sometimes accidentally we eat parts of the hard endocarp and spit them out dramatically (at least Beans does).  

Pumpkins are the fruit of Cucurbitaceae plants. The fruit is actually a modified berry called a pepo that has a thick outer rind. Berries are simple fruits where the seed and flesh is formed from a single ovary. Other common berries? Avocado, watermelon, blueberry, cranberry and tomato. What’s not a berry? Strawberry (accessory fruit), cherry (drupe) and raspberry (aggregate fruit). So once again what we call things in real life versus what they are botanically makes no sense.

Bunny’s very first no help at all carved Halloween berry

I can’t find a decent picture of the parts of a pumpkin so here’s a watermelon, just to prove it’s a berry, because I got a seriously unbelieving face from Bunny. She was quite willing to accept that pumpkins were a berry but watermelon was a little out there for her. Same deal though – the ovary forms three parts but in this case there is no surrounding tissue that forms the edible part (why it’s a berry and not a pome). The part we eat here is the mesocarp and the exocarp is the hard rind that makes an excellent jack-o-lantern. The endocarp isn’t shown in this one but it’s there surrounding the seeds.

We all agree though, no matter what you call them – they are still delicious. So whether cooked or raw, pie or plain – we will continue eating lots of fantastic fall fruit (I just wanted to do the alliteration again).