Cyperus retrorsus - The Cylindric Sedge

 

Trinity River Audubon Center - July 26, 2013

When I first saw this plant at TRAC what caught my eye were the burr-like structures.  Taking a closer look revealed something unexpected - a triangular shaped stem - an identifying charactersitic of sedges.  As I was told by Ron Beecham, a professor of Biology here at the college, "Sedges have edges."

Here is a detailed look at the Cylindric Sedge (Cyperus retrorsus)



A photo from the field.  I have memories of running barefoot as a young boy and stepping on rather large cockleburs.  When I took a closer look what I found was not the stickery fruit of the cocklebur, but the typical, incomplete flower of a grass.

A photo from the field showing the flowers of the sedge.

I took a specimen back to the lab for more photos and for examination under the dissecting scope and the scanning electron microscope.

This photo shows the flowers of the sedge.  (Anyone familiar with the 3rd floor of the C Building at Eastfield College will probably recognize the patio where I took this photo.)  Also notice the three-part symmetry, typical of monocots.

In this photo you can see the multi-part flowers and even some of the anthers hanging out of the flowers. 

If you haven't studied botany, or have forgotten what you knew when you took it, it may seem a little confusing for me to use the term flower.  Where are the petals?  Lots of plants produce flowers without petals.  This includes most trees, grasses, and, in this case, sedges. 

 

Complete flowers contain all four of the major floral parts: sepals, petals, stamen -the male parts that produce the pollen, and the pistils or carples which contain the eggs.  We are most familiar with complete flowers and love their colorful, showy petals.  But there are also incomplete flowers which are missing one or more of the floral parts.  Grasses and trees often don't have petals, but they still reproduce sexually, just like those roses you may have given or received on special occasions.

 

A flower is the reproductive structure of a plant.  Some flowers contain both male and female reproductive structures on the same plant and are called monoecious (Greek for "one house").  Other flowers contain male or female structures on different plants are are said to be dioecious ("two houses").

This sedge has monecious, incomplete flowers.

Here is a closer look using the dissecting scope in the lab.

I brought the sedge back to the lab, put the stem in water and left it in the window over the weekend.  This little bug didn't seem to mind at all that the sedge was no longer outside.  It was happily crawling around and munching pollen.

Here you can get a sense of the structure of these flowers.  They are made up of overlapping segments with anthers and stigmas sticking out.  The white arrows in this picture indicate anthers.

 


Here is one section showing the structure. Each segment is a flower  and

has an anther and stigma and will produce a single seed.

The  next images were made with the scanning electron microscope. 

 

This structure is pretty small, only about 5 mm or about 1/4 inch long.  Each overlapping segment is a separate flower.

[40x]

 

At 200x you can see lots of details.  The anther has split open and spilled out its pollen and you can see the stigma.  (Unfortunately, the electron microscope dries out structures very quickly, so the pollen grains and cells of the stigma are collapsed.)  Even though these are the reproductive structures of the plant, they are still green and photosynthetic so they need to take in carbon dioxide and and release oxygen.  That is why you see stomata here. 

 

For this image I have turned the structure on its edge to show an anther hanging off.  These are actually visible with the naked eye and you can find them on the St. Augustine and Bermuda grass in your yard. [56x]

Same anther at 150x.  Here you can see it is split open and has pollen spilling out.

Several anthers at 190x.  Turns out it is very easy to cause these to fall off of the plant.  I shook the plant over my mounting stub to collect pollen and also found these. 

Anther with pollen at 300x.



Pollen grains at 1,700 x magnification.

The software on the scanning electron microscope allows me to make very precise measurements.  As shown in the image at 1,700x the pollen grain is only 22.61 microns x 29.90 microns.



I have to admit that I am very pleased with this image.  It shows the detail on a pollen grain at 5,000x magnification. 

Of course, the purpose of all of this structure is to make seeds.  Once the pollen falls on the stigma of the flower and fertilization occurs the seed will develop.

This image from the dissecting scope shows a couple developed seeds. Notice that the flowers are larger on the bottom of the structure because they develop first and are older.

I have pulled back the covering to show the seed underneath.  You can see the stigma still attached to the top of the seed.



The seeds on under the dissecting scope.  These are very small.  Notice the scale bar showing 500 microns or 1/2 mm.

65x magnification on the scanning electron microscope.  The total length of this seed is less than a millimeter.

Another seed for comparison. 

A close up of the attachment of the stigma to the seed.  350x

What about those triangular stems?  Here they are.

This is a cross section of the triangular stem.  Notice that the green, photosynthetic cells penetrate deeply into the stem.



Same view as above on the scanning electron microscope.  14x

Dissecting scope view of edge of stem.

Electron microscope view of stem edge. 230x

Electron microscope view of stem edge. 936x

 

More than 40 years ago my biology teacher at Borger High School, Mrs. Eve Wyles, taught me that you can always tell the cross-section of a monocot plant because the bundles of vascular tissue resemble monkey faces.  "Monocots have monkey faces."

 

This sedge is definitely a monocot.

 

Bundles of xylem and phloem,  monkey faces, indicated with arrows.  70x

More monkey faces.  130x

This one is for you, Mrs. Wyles.  450x

I really love going into the field each week and never know what will grab my interest.  I seem to learn something new every time.  Sedges?  Why not.

Please do not hesitate to contact me if you have comments or questions about this posting.  All images may be used, downloaded, or modified as long as you give credit to Eastfield College, Mesquite, TX. 

Murry Gans

Can you help me identify this wildflower?

I came across a wildflower at the Trinity River Audubon Center that I cannot identify.  I thought I would draw on the collective expertise of the folks who read this blog.  If you have any idea what this plant is, please let me know in the comment section.  Many thanks in advance.

Trinity River Audubon Center, 6500 Great Trinity Forest Boulevard, Dallas, TX 75217, USA
street address:	6500 Great Trinity Forest Boulevard
ZIP/postal code:	75217
neighborhood:	Trinity River Audubon Center
city:	Dallas
state/province:	TX
country:	USA
latitude, longitude:	32.7124233, -96.7088488 32.7124233 -96.7088488 N32° 42.7454', W096° 42.5309' (precision: feature/building)

http://www.gpsvisualizer.com/geocode


It is obviously a composite flower with a raised disk.





 

This is a very large image of the entire plant showing the stems and leaves.  Notice the keels on the stems.  The plant stands about a meter high.
 

Let me know what you think and many thanks in advance.


M. Gans
Eastfield College
Mesquite, TX

 

Trinity River Audubon Center - June 28, 2013

It was supposed to be 104 today so I got out early, arriving at Trinity River Audubon Center at 7:30.  Luckily, it was a cloudy morning and by the time I left at 11:00 am it was only 89 degrees.  It was plenty hot, but the clouds saved me.

While clouds are good for staying cool, they are not so good for my point and shoot camera, but I still got so decent images of lots of flowers and insects.

First, lets take a look at some plants.

This is a plant that I saw everywhere this spring - Queen Anne's Lace (Daucus carota).  This is a very prominent roadside wildflower in North Texas and it is not uncommon to see entire fields of Queen Anne's Lace.  It is an alien species to our area. (1)

Next is the Partridge Pea (Cassia fasciculata).  According to Southwest and Texas Wildflowers, this should be in bloom from June through October. (1)

The image above shows the pea pods and red center of the flowers that help to identify it.  The leaves are supposed to be sensitive and fold up when touched, but I didn't test this (or at least notice it) in the field.

 

 Large stands of partridge peas at TRAC.

 This image shows some unopened buds as well as some drops of water resulting from a process called guttation - the forcing of water out of the plant due to root pressure.  This usually occurs early in the morning when the soil is damp.

In this image you can see the leaves of the partridge pea.  They are pinnately compound.

 



 Here is our old friend Coreopsis tinctora. 

 A close up of Coreopsis with a dried seed pod.

Today Coreopsis has a little surprise for me - a red and black beetle munching away on pollen and nicely camouflaged on the center of the flower. 

This where I wish the sun had been out.  My little point and shoot camera took a very slow exposure making the beetle a little out of focus.  Dang!

 

 Here is another look at a wildflower we have seen here before, Firewheel (Gaillardia pulchella) (1)

The pom-poms are flowers that have been pollinated are are setting seed.

 

 Helianthus annuus - The Kansas Sunflower. 

Woolly Hibiscus (Hibiscus lasiocarpos)  Absolutely beautiful.  I had to thrash my way through lots of brush to get to this plant. 

 



Here you can see the deep red in the throat of the flower and several unopened flower buds.


 A small jumping spider on one of the Hibiscus flower buds.



I believe this to be an Ivyleaf Morning Glory (Ipomoea hederacea) due to the variable leaves - some heart-shaped and others trilobed on the same vine.  (1)

 Here you can see the two different types of leaves. 

 

This is Oenothera speciosa, also known as Pink Lady.  These really enjoyed the unusually wet spring that we had this year and are at the end of their season. (1)

 

 

Next is a plant that I see everywhere at TRAC.  The insects love it and I have been watching it grow, waiting for it to bloom.  I am pretty sure that it is ragweed so I probably shouldn't be so excited for it to bloom.  I noticed that the snout beetles I had found before are all over this plant and copulating like crazy, sometimes 3 or more piled on top of each other.  (In my field notebook the notation reads, "SEX, SEX, SEX!")

 

I also noticed some interesting damage on the stems of the plants and was wondering if these snout beetles were burrowing into the stems and laying eggs. 

 

 

I decided to take some of the damaged stems back to the lab and made another interesting observation. 

 

These plants produce a dark red pigment when cut.

 



And you get to see my pocket knife.  The red on my finger is plant pigment, not blood.

 



 

One last plant is the Texas Thistle (Cirsium undulatum).  Notice the shiny flowerhead bracts that are long and narrow.

 Here you can see a leaf-footed bug on a Texas Thistle that has gone to seed.

Here is another hemipteran that decided to land on me instead of a plant. I guess he wanted his picture taken.

I I I II a
Ia Ialso found this very pretty hemipteran nymph nicely camouflaged on a leaf.  Notice it doesn't yet have wings.

This little guy is Graphocephala coccinea. (2) I remember this bug from when I was a youngster.  When I found one I couldn't believe the colors.

I I_also ran into a turtle taking advantage of the trails at TRAC. 

Because of the weather forecast of excessive heat I had considered skipping this trip to TRAC but am delighted that I didn't because it turned out to be a great day.

 

References:

 

(1) Niehaus, Theodore F. A Field Guide to Southwestern and Texas Wildflowers. Illus. Charles L. Ripper and Virginia Savage. Boston: Houghton, 1984. Print.

(2) Borror, Donald J., and Richard E. White. A Field Guide to Insects: America north of Mexico. Boston: Houghton, 1970. Print.

If you have any questions or comments about this blog please do not hesitate to contact me at Eastfield College in Mesquite, TX.

All images are under a  Creative Commons License and you are free to use them anyway you like with attribution to Eastfield College.  They may not be sold.