Thursday, March 23, 2017

Redbud Spring at Eastfield College

As a Texas boy I am no fan of cold, or even cool weather; I like it hot so I am always delighted when spring finally arrives and I can spend my weekends in shorts and flip flops.  One of my favorite signs of spring is the blooming of the redbud trees, Cercis canadensis, and this year I was delighted to see that our outstanding, Eastfield College grounds crew had planted two new redbud trees flanking one of the entrances to my building. 

This first group of images were made with my trusty Nikon Coolpix P520.

My current, favorite redbud trees.

Makes you want to sit for a while.  See - Texas isn't all burning desert - at least not right now.

What makes the redbud so beautiful are the large clusters of flowers and their amazing colors.

These redbud flowers are fully open.  You can see the tips of the stamen and pistil peaking out.

Of course, the purpose of flowers in not to impress humans, but to attract pollinators.  I got very luck to get this shot of a bee happily harvesting pollen and nectar.  You can see pollen baskest on its hind legs.  The flowers at the top of the image are pollinated and have begun to drop their petals.

A small, hairstreak butterfly attempting to sip nectar.  If you look closely, you can see that its tongue is touching the outside of the flower.

The picture isn't sideways, the butterfly is.

Petals gone, these pollinated flowers are producing seed pods.

I took some samples back to the lab for a closer look with a dissecting microscope.

The tip of a branch through which new leaves have emerged.  Note the scale - 5mm is about 1/4th of an inch.

The newly emerging leaves also contain some red pigment.  The hairs on the underside of the leaf are called trichomes.

This image shows a bud that has lots of flowers.  The color of the sepals is more vivid than the petals themselves. As shown in the next image, this gives the flowers a two-tone effect.

A single redbud flower.  Let's disassemble it and see what is inside.  (Typical biologist - find something pretty and tear it apart to see what is inside and how it works.)

Removing some of the petals reveals the stamens and pistil.

The reddish anthers open to reveal yellow pollen.  The female stigma and style is just visible behind the stamens.  It is the thicker structure.

A close up of the filament and anther.  You can see the individual, pigmented cells of the filaments that hold up the anthers so pollinators are sure to get coated in pollen when they visit the flower.

The stamen in front have been removed to reveal the style and stigma.  The stigma is covered in yellow pollen.

With all of the petals removed you can see the base of the stamen and pistil. Talk about gorgeous colors!  

In this image you can see the individual cells containing pigment.

This is an older flower that has been pollinated and the ovary is beginning to develop into a seed pod.  The thickened orange area is where the seeds are developing.

These are flowers with more developed seed pods.  Note the same colors on the pods as in the previous picture.

I have removed the remaining petals so you can see the seed pods.  This type of fruit - a pod that opens along the seams on two sides - means redbuds are legumes, right there along with peas, lentils, bluebonnets, beans, and mesquite trees.

One of the seed pods is sliced open to show the developing seeds.

Developing seeds.  Once fully developed, the seed pod will dry out and form the dry, brown pods you find on these trees.

The following images were made with the scanning electron microscope.

At 31x magnification, you can see the reproductive structures of the redbud in detail.  (Warning: Botany Ahead!) The style connects the stigma to the ovary containing the eggs. The stigma contains sugars that allow pollen grains to stick and germinate forming the pollen tubes and two sperm each; one to fertilize the egg to form the embryonic plant and the other to merge with the two polar nuclei to form the triploid endosperm.  The endosperm is a starchy substance that feeds the developing embyo until it can grow some leaves to begin photosynthesizing. This starchy goodness is also why we eat seeds - try not to think about eating all those little embryos.

Pollen grains from the redbud flower magnified 1,600 times.

We live busy lives, and hundreds of people walk right by these two redbud trees everyday - often staring at a cell phone or looking straight ahead on the way to and from the parking lot.  There is a lot of beauty to be found in the natural world - even if you don't have microscopes.  Slow down and take to time to actually see what is around you.  It can be amazingly beautiful and is always interesting.

And thanks for letting me talk a little botany to you - it wasn't that painful now, was it?  :-)

Murry Gans
Eastfield College Microscopy Lab
Mesquite, TX

Friday, June 3, 2016

Roses - More Beautiful Up Close

The landscaping here at Eastfield College is well maintained and can be unexpectedly beautiful.  I was involved in a student/faculty mixer recently and set up a dissecting microscope with a large screen display for students to use.  At the last minute I dashed outside to see what extra samples I could find and brought back in some roses.  In the process of pulling the roses apart and putting them on the microscope I began to see some really beautiful structures.

These are" knock-out roses" which do well in our hot summer climate, bloom continuously, and are very disease resistant.

[Let me say up front that I am a bit color and color name challenged, so my descriptions below may not exactly agree well with what you see.  When I say red it could actually be pinky-red or dark pink, or . . . well, you get the picture.  I refer to the colors to give landmarks for naming structures.  It should be close enough for you to see what I mean.]

OK.  Big Deal.  Red roses and green leaves. Not so fast.  I took some flower buds and open flowers back to the lab to image.  What I found might surprise you.

The images below were made with a dissecting microscope with a digital camera.

The image above shows a longitudinal section of an unopened rose bud.  Flowers are actually modified leaves.  The parts of a flower grow in circular whorls.  The outer most layer are the sepals, which surround and protect the developing flower; then the petals, for attracting pollinators; the stamen, or male parts of the flower that product the pollen; and in the middle the carpel, or female part which contains the eggs.  The swollen part of the stem below the flower parts is the ovary.  You can see several ovules in the ovary, each of which contains a single egg that could become a seed.
This is a close up of the ovary.  The seed-like structures are ovules which hold the eggs.  You can see the filamentous styles leading from them to into the flower.
Here is a close up of the unopened flower bud.  Just inside the reddish petals are the developing stamen and in the center are the carpels with a blush of red on them.
This image shows the stamen of a newly opened flower bud.  The anthers have not yet split open to begin releasing pollen.  The colors really surprised me.
This image is a closer look at the maturing anthers. I really love the colors in this image, no matter what their names might be.

This is a fully opened and mature rose flower.  The green carpels that protected the unopened bud are seen below the petals.  Above the petals are the pollen-producing stamen and in the center the red structures with the yellow tips are the stigma and style - two of the female parts of the flower.

On the right side of this image you can see the pink filaments that support the anthers.  The anthers produce the pollen.  A close look at the top right will show some anthers that have broken open to show yellow pollen.  The left side of the image is the top of the female part of the flower.  At the bottom is the ovary (not shown).  The pink/red filaments are the styles - they connect the yellow tips to the ovaries.  The yellow tips are stigmas.  When pollen grains land on the stigma they germinate and grow a tube all the way down to the egg in the ovule.  The two sperm cells formed in the pollen grain will make their way down the tube to the ovule where one of them will fertilize the egg.  Plant sex turns out to be very weird.  Look up "double fertilization in angiosperms" on Google.
Yellow stigmas on top of styles.  Some of the yellow spots are pollen grains.

Here are mature anthers at the ends of their filaments. You can see the yellow pollen grains emerging from the edges of the anthers.

This is the edge of the unopened flower bud.  Male anthers on the left, then the stacked petals, then the surrounding sepals.  Being a rose, there are thorns. The small thorns on the outside of the sepals have secreted some reddish liquid.
More thorns secreting reddish liquid.  The base of the ovary is at the top of the image.  Note the red blush on the thorns.
Here is a fully developed thorn from farther down the stem.  The drop of liquid is gone, but the red blush is still there.
This is the underside of a rose leaf.  Most obvious is the serrated margin of the leaf.  You can also see the veins of xylem and phloem that carry water and sugars.  Again, there is red blush everywhere.

This image is a close up look at a vein on the underside of the rose leaf.  I have illuminated the leaf from the bottom.  The outer layer of cells on the vein are pigmented.

The images below were made with a scanning electron microscope.  Unfortunately, these images are in black and white, but the structures are still interesting.

A rose petal feel like velvet when you touch it.  In the image above you can see why.  The petal is made up of thousands of raised cells.  Magnification = 131 x.

Here is a closer look at the cells that make up the rose petal. Magnification = 1,110 x.

When roses carry out photosynthesis, they take in carbon dioxide and use it to produce sugars.  A by-product of carbon dioxide is oxygen (thank goodness).  The image above is of the underside of a rose leaf.  It shows the mouth-like stomata that allow gases to move into and out of the leaf.  Magnification = 650 x.
I wanted to see what the pollen of the rose looked like.  Here is a view of an anther (left) with the pollen grains spilling out (right).  Magnification = 450 x.

Much to my surprise, the cells that make up the anther are highly folded.  Their structure is pretty amazing.  Magnification = 950 x.

Using microscopes to see the small beauty of roses reminds me of a one of my favorite quotes from Henri Poincare, a French mathematician from the late 1800s.

"The scientist does not study nature because it is useful to do so. He studies it because he takes pleasure in it; and he takes pleasure in it because it is beautiful."

Best wishes from the Eastfield College Microscopy Lab.

Murry Gans

Please feel free to use images from the lab for non-commercial purposes and please give credit to the Eastfield College Microscopy Lab, Mesquite, TX.