This illustrates, essentially, how water moves through a tree – the water evaporates from the leaf (in our experiment, that’s analogized by the cotton ball), which pulls it through the xylem (the straw, in our table top set up), which in turn pulls the water out of the soil (which is represented by the glass that holds the tinted water). Either way, after a while, you’ll see the dyed water migrating up through the straw, ultimately dying the cotton ball whatever color you have chosen from your pack of food dye, that you used to stain the water in which the straw is sitting. Then, place it, cottonball end up, into a glass with more water in it, but this time with water that has a little bit of food coloring in it. In fact, you can see how this works by taking a drinking straw and putting it entirely underwater so it fills with water, then taking a piece of a cotton ball and jamming it tightly into one end of the straw and then taking the entire contraption up and out into the air. The way that water moves up a tree is, basically, that the water evaporates from the leaves through little holes, called stomata this evaporation draws the water up through tiny pipes, called, collectively, xylem, in a somewhat similar way to how water goes up through a straw when you draw on it as it sits in your waterglass. And so those little tufts of leaves at the bases of the inflorescences are quite likely feeding their neighboring buds and blooms.Īnd also, those leaves could be beneficial to the tree by drawing up water, pulling it towards the flowers, who need to drink, too. And by having those leaves right there in the bud, good timing is assured – no need to wait for the leaves farther away to open up (which they will later) when you have your own right there in the package with you. By having the leaves right next to the flowers, the source right next to the sink, this would save precious time and energy, always a valuable set of resources, but resources even more valuable in the spring, just after the trees have woken up and are drawing down their stored energy supplies, supplies that they packed away last year and have only in limited amounts. It’s expensive to ship sugar around a tree, as it takes energy to move things, and so doing it locally, right next to the inflorescence, instead of having the leaves come up some distance away and transporting the food that some distance, it would just simply be more efficient to do it closeby. Why are those leaves there and what are they doing? It could be that they provide a local food source for those flowers, early on in their development – those photosynthesizing leaves harvesting energy from the sun and gathering carbon dioxide from the atmosphere, twisting the two into sugar, and shipping that sugar right to the nearby flowers, flowers that need energy to grow and to breed, these leaves open up when the flowers do, since they are in there in the bud with them, and they pop out along with the flowers, and would provide sugars just a short distance away, and at the right time.

At the lowermost position on the inflorescence, the one closest to main part of the tree, there is almost always a set of a leaves, a little tuft of green, instead of a flower. Each one of those flowers is accompanied by a little tiny leaf, or a leaf scar to show where a leaf once was – each one repeats the other, in modular form, winding around the stem, up and down the line. Look closely, and poke around in the inflorescence (a cluster of flowers, that is) and you’ll see that each individual flower is connected to a little stem, in a somewhat spiral arrangement, winding down the axis, or winding up it, depending on which direction you go. If you look closely at them, one thing that you’ll notice is that nearly every set of flowers is accompanied by its own set of leaves. Some are cherries, and there are others, too, but most of the ones that you’ll see at around this time are the blooms of the Callery pear ( Pyrus calleryana), with their copious flush of white and their peculiar acrid smell.

Some of those white flowers are magnolias. Some of them belong to the Amelanchier, also called shadbush, or serviceberry. There are white flowers blooming all over Philadelphia now.

Bacterial blight of callery pear