Submitted by Cameron Ross
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Last Tuesday on February 14th we went to the Library into a room on the 5th floor called the Bernard room. Here, we got into pairs to use one of the many computers in there that had a program called AISO. AISO is a program that's used to annotate images (like cross-sections of leafs) using ontology terms from the website Planteome.org. We used this time to annotate the pictures we had taken for our individual Natural History Projects, and if you ask me, there's no more romantic way to spend Valentine's Day than annotating pictures from our plants. Unfortunately for us, AISO is a fairly old program and has many bugs that makes it hard and frustrating to use. I wasn't able to annotate my pictures properly because of this, but luckily, I think it worked out. As you can see, I wasn't able to get AISO to properly annotate my image. The trichome came out relatively good, but the vascular bundle wasn't highlighted, although it was annotated. It's a good thing that it's easy to see as it's simply the big, dark spot in the middle. It was also hard to annotate the mesophyll but they're the white spots all throughout. I think a structure I should've annotated (but I didn't realize it was there due to time-constraint) was the palisade parenchyma cells on the top right. These elongated cells contain many chloroplasts and is the layer most responsible for photosynthesis. I showed the diagram of a dicot leaf for reference of what we're seeing in my images. It's good to note my image is slightly out of focus because my slice wasn't cut straight. Overall, this was a great experience and I wish a newer and updated version that fixed most of the bugs for AISO was released. It was a very fun lab nonetheless.
-Adalberto Marquez Submitted by Tyler Yates In lab we examined various roots from two different dicot plant specimens. Pisum Sitivum (pea), and Vicia faba(bean). Cross sections were prepared and examined under a compound microscope. The picture below on the right is a cross section of Pisum Sativum and an annotated image to the left identifies the structural internal components. Notice the external root hairs stained dark blue surrounding the epidermis. internal to the epidermis is the cortex made up of the larger clear parenchyma cells of the ground tissue. The group of cells in the middle is the stele, or procambium. The procambium includes the vascular tissues as well as the pericycle; surrounded by the endodermis. The pericycle, in dicot roots, gives rise to lateral roots, cork cambium, and portions of vascular cambium. Notice that the pith is absent in dicot roots . In lab on Thursday February 16th we explored root structures of monocot and dicot roots. Our class examined a Corn plant to identify parts of the root. Monocot roots have adventitious roots where lateral roots give rise to fibrous roots. These type of roots do not have a primary root, but instead have many that branch out from the stem. Although the structure of the monocot and dicots are different, they still encompass the same internal anatomy. The image below on the left shows a picture of a Corn plant root through a microscope. The cross-section was stained with TBO and the microscope magnification is at 40x. The image on the right is a drawing of a monocot root with its labeled parts. The third image is another example of a monocot root structure. The epidermis layer of cells is found the outermost edge of the root and is the same for both monocot and dicot roots. In from the epidermis is the exodermis layer of cells (not labeled in on the image). Next is the cortex, which is made up of all the cells between the exodermis and the endodermis. The endodermis is the first, outermost layer of dark cells. The next layer of dark cells in known as the pericycle. The the larger bubble looking circles are the xylem cells. Surrounding the xylem cells are the phloem cells. The pith is the innermost cells from the xylem cells. Lastly, the stele is the area inside the endodermis cells.
By Keira Mitchell By: Chelsea Maddox Just this last week in lab on Thursday, February 16th we took a look at structure of roots and their external features. From what we have learned so far about roots is that they have many functions. One: they anchor the plant to a substrate. Two: absorb water and minerals. Three: they conduct water, mineral, and carbohydrates. Four: roots store the carbohydrates while playing an additional role in asexual reproduction. The external features and structure of roots is very important because they are associated with how they carry out the above functions. Plants have two types of branched root systems. One being a fibrous root system and another being taproot system. Angiosperms have been classified into two major groups known as monocots and dicots. The monocots is associated with a fibrous root system because they are commonly short-lived so they are composed of adventitious, branched roots. So you've probably guessed by now, dicots are associated with the taproot system because the plants strive to live longer. The taproot system has a primary root that develops as a taproot which then gives rise to secondary, adventitious, branched roots. The images I am going to show below are of corn (Zea mays), a monocot with a fibrous, adventitious root system.
Unlike corn (Zea mays), a broad bean plant (Vicia faba) is a dicot with a taproot root system. Even though the root system isn't fibrous, it is still considered to have adventitious, branched roots. Below are some images I took in lab on Thursday, February 16th of the mature broad bean plant. Unfortunately, I am unable to label the close up view of the dicot broad bean with the taproot system because it just looked like mess because the picture I have of the root are bunched together too tight. However, to the left, I have uploaded an image of the broad bean root system labeled for a better understanding of the difference between monocot and dicot root. Numbers 4 and 5 I feel do a great job pointing out which part is what in these figures. One thing I found interesting in class and I was highly encouraged to present within this blog is the unique nitrogen-fixing organs that result from a symbiotic interaction between the plant and nitrogen fixating bacteria known as root nodules. Most legumes result in infection by bacteria of the host-plant root. More information of how the process of infection begins you can gather from recommended reading (Ch. 29, pgs. 693-700 in Raven's Biology of Plants). Assuming the recommended reading was done before lecture on February 9th, you may remember reading about the two different types of root nodules. They can be distinguished by either indeterminate or determinate. Indeterminate root nodules are elongated and cylindrical due to the presence of the meristem. However, the determinate root nodule is presented in spherical form due to the lack of the persistent meristem. The image I will be showing you below is of indeterminate root nodules on the roots of a mature broad bean plant. These nodules on the mature broad bean are common of the legume (Fabaceae) family. "Legumes secrete compounds called flavonoids from their roots, which in turn trigger the secretion of nod factors in the rhizobia. Coming full circle, the nod factors spark a reaction in the legumes, causing the roots to swell and form the nodules you see here. It is within these nodules that rhizobia live in harmony with their host plant."
Read more at http://www.gardenbetty.com/2012/11/a-look-at-legumes-rhizobia-and-root-nodules/#ZV650Ij8EhVTtrGs.99 The coolest part about lab on Thursday was getting to cut open the root nodule on the broad bean plants while examining it under the dissecting microscope. When cut open, the nodule represented a pinkish/red color (pictured below). The nodule having the color inside represents the presence of leghaemoglobin which means the nodule is active and is fixing a lot of nitrogen for the plant. FUN FACT: the redder the nodule, the more ACTIVE it is! Blog by Max McDonald Week 5 already in the books!! Wow the term really does fly by when your having so much fun learning about plant structure and botany with Dr. LP! Any way get ready to learn about some leaves and grass for your cat. First things first, whats up with these leaves? Just bud + leaf? simple right? Wrong! In the above image we see an example of a compound leaf. Compound leaves form from the same place as simple leaves, axillary buds. Compound leaves are made up of a petiole, that stems from the shoot, and multiple leaflets growing directly from the petiole. It is easy to mistake leaflets for leaves, but don't be deceived by their similar form and function! Leaflets come in clusters, on petioles, while leaves come directly from the shoot, one petiole to one leaf. I took the above image in class last Thursday. You can clearly see all of the the features that make up a compound leaf. A petiole stemming from an axillary bud, 5 leaflets stemming from the petiole, the bud sitting above the petiole, and even some axillary prickles! ouch! I could talk about compound leaves all day! so cool ! but, there are more pressing leaves at hand now that you are informed about the complex ones. Buckle up. I bet your wondering about the arrangement of leaves on a stem or axis. me too. If only there was a word for that...Well, I hope you buckled up, because guess what? There is. Phyllotaxy comes in many different forms, but in the interest of brevity, i'll only enlighten you with two. Firstly there is opposite phyllotaxy. In opposite phyllotaxy the axillary buds stem from opposite sides of the stem, just like in the below picture. Secondly there is alternate phyllotaxy. Unlike opposite phyllotaxy the axillary buds in alternate phyllotaxy's alternate down the stem. This leaves open space directly across from and bud on the shoot. The image below is an example of some alternate phyllotaxy on a piece of english ivy from lab. When is this guy going to get to the catgrass?! Don't worry, right MEOW! Below is an example of a cross section of the aforementioned grass for your cat, more commonly known as wheat grass, a C3 grass. You can see the upper epidermis, which uses translucent cells to focus light into the mesophyll cells. Also visible in the middle of the cross section is a vascular bundle. At the very bottom of the cross-section is a stoma. The stoma is a pore in the grass that allows for greater absorption of CO2. The stomatal pore is opened and closed by guard cells on each side. The CO2 enters the stomatal pore and absorbed by the water that surround the mesophyll cells. Check out the stoma and guard cells visible is this epidermal peel below! interesting and beautiful!
Submitted by Emily Burkhart I'd like to start off by saying ♥Happy Valentines day♥ to everyone! In this blog post we'll explore dicot, pine and simple leafs. All the information below has been gathered from lab on Tuesday and Thursday of week 5. Dicot leafBroad Bean Vicia Faba plant was used in class for a look at the cross section for a dicot leaf. There are two groups that all flowering plants or angiosperms were formerly divided into. How they were decided which group they belonged in depended on their characteristics. These two groups are monocots and dicots. The images below are images of the plant and the cross section of the plant broad bean. When looking at the difference between monocots and dicots there are 6 characteristics to look at; seedpod, flower, stem & roots, leaves, germination, and seeds. Here is a link to a really good website that gives more information at distinguishing these differences : http://theseedsite.co.uk/monocots2.html The above slide was taken in class at the magnification of 100x. It is the cross section of a broad bean leaf Simple leafTo the left are 16 examples of what some simple leaves can look like, but what does it mean to be a simple leaf? A simple leaf: An undivided leaf; as opposed to a compound leaf. The blades are not divided into distinct parts, although they may be deeply lobed. Below are some examples of common simple leafs. The two images were from: http://biology.tutorvista.com/plant-kingdom/leaf.html This is also a really good website for a quick summary and run down on comparing leaves FUTURE LOOK > Later in the blog, compounds leaves will be discussed and looked at when comparing simple and compound leaves, but below is a really good video for when identifying the differences and what to look for! Pine leafThis is my favorite kind of pine, Knobcone pine, Pinus attenuata. Knobcone pines is a tree that grows in mild climates on poor soils. It ranges from the mountains of southern Oregon to Baja Califonia with the greatest concentration in northern California and the Oregon-California border. ________________________________________________ FUN FACT: It's actually incorrect to call them pine cones because cones can come from fir trees as well. So they are actually just known as cones and depending on the tree it comes from depends on if it is a pine-cone or a fir-cone. There are around 100 pines, all of which are characterized by an arrangement of leaves that is unique among living conifers. After a year to two years is when the pine will produce needle leaves in a bundles, or fascicles which contains a certain amount of leaves depending on the species. These fascicles are wrapped at the base in small scalelike leaves, and are actually short shoots in which the activity of the apical meristem is restricted so the fascicle of needles in a pine morphologically is determinate. Fascicle: A bundle of pine leaves or other needlelike leaves of gymnosperms; an obsolete term for a vascular bundle. The two cross sections above of the pine leaf were taken at the magnification of 100x. Both images were taken during lab.
Last Tuesday in lab we studied about exploring the stomatal complexes of monocot leaf vs dicot leaf. We also learned about the internal structures of different leaves as well as their primary functions such as photosynthesis and transpiration. Stomatal Complexes of Monocot vs. Dicot Wheat cat grass is known Tritium vulgare, is monocot plant. Stomata of the wheat "cat-grass" (Tritium vulgare) consist of four cells, two guard cells and two subsidiary cells. The guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that form a stomatal pore. Broad bean is known Vicia faba, which is the dicot plant. Stomata plays a vital role in openings in the epidermal layer that allow for the exchange of gases. They allow for a plant to balance water inside and outside the cells. Guard cells allow for the opening or closing of the stomata with the internal hormone stimuli as well as external environmental factors. Pavement cells are simple cells with no real functions other than protecting the cells below them. Moreover, they help decrease water loss, and maintain an internal temperature. The most significant difference between the stomata of the monocots and the dicots is the shape of the guard cells. The monocot leaf has the narrow, dumbbell-shaped guard cells; whereas the dicot leaf has the pair-of-sausage shaped guard cells. Moreover, the monocot has the guard cells arranged in regular arrays, but the dicot has different paving. The monocot has stomata on both the upper and lower surface of the leaf. However, the dicot has stomata on the lower surface. Cross-Section of Corn Leaf (Zea mays) Corn leaf (Zea mays) is monocot, has parallel veins. Moreover, spongy mesophyll is composed of parenchyma cells that contain chloroplast for photosynthesis. It also has air spaces for gas exchange and produces carbohydrates by photosynthesis. The upper and lower epidermis protect the leaf from water, sealing water inside and preventing parasite's attack. Xylem transports water into the leaf while phloem begins the sugar transport down to the roots. Veins is consisted of xylem and phloem, and a surrounding bundle sheath. The internal structures of the monocot plants compared to the dicot plants made me surprised because I've always thought that their insides looks the same. However, there is a big difference. Guard cells of the monocot are narrow, dumbbell-shaped; but they are crazy-paving arrangement in the dicot. Stomata are located on both the upper and lower surface of the monocot leaf; whereas they are located only on the lower surface of the dicot leaf. During the lab, I felt difficulties in doing the cross-section of corn leaf because it needs a good skill technique to cut the cross-section. Finally, TA help me to finish the slide; the one I got that make me happy.
Submitted by Quyen Ta This week we looked at a few leaves belonging to plants that have adapted to survive the niche in which they found themselves. Waterlilies have adapted to survive floating atop bodies of water, the rubber plant has adapted to survive tropical and equatorial climates, and the oleander has developed advantages for surviving in very dry climates. The Nymphaea (waterlily) leaf has stomata on top of their leaves instead of below to allow for increased air exchange and nutrient exchange; they do not have a defense against transpiration as other plants do in the form of guard cells. The loss due to transpiration is not a primary issue for the waterlily since it has extremely good access to water. The sclereid labeled above is meant as a support for the leaf; it helps tent up the leaf which allows for greater air exchange in the leaf air space and provides flotation for the pad. The cuticle of the leaf is quite thin and helps repel water from the stomata. -Chris Barrett The sunken stomata of the Ficus plant helps the plant retain water. By not being flush with the rest of the epidermis, the stomata allow water vapor to be released yet not be immediately blown away by wind, therefore retaining an amount of water for reabsorption. The hypodermis is quite thick on top of the palisade mesophyll cells, perhaps for protection from intense UV radiation. The sub-stomatal regions are quite large, allowing for greater gas exchange in the mesophyll cells. There are not any trichomes visible on this leaf section. This large open areas in the spongy mesophyll, the sunken stomata, and the thickened hypodermis point to this plant being able to survive very hot, and very sunny climates, perhaps in the equatorial region of the world. -Chris Barrett The adaptations of the Nerium oleander plant have allowed it to survive in very dry climates. These are evident through the presence of stomatal crypts, which contain multiple stoma positioned far away from outer line of the lower epidermis. There are also trichomes present near the openings of the stomatal crypts. Both the presence of the stomatal crypts and the trichomes located inside of them point to adaptations for survival in very dry climates. The increased presence of plant fibers in the leaves allows the leaf to maintain its shape even when its other cells are plasmolyzed in dry spouts. Its multiple epidermis and thick cuticle allows the plant to handle high ultra violet radiation.
Regardless of the fact that every part of the plant is toxic to humans and other animals, it is one of the most widely grown plants in the world due to its drought-resistance with uses including ornamental, medicine, and wind-blocking. The oleander plant is also the official flower of the city of Hiroshima as it was the first plant to flower there after the destruction of the city by nuclear blast. -Chris Barrett Submitted by Tyler Hardy In this week’s lab, we took a close look at the characters of woody twigs of vascular plants. It may not seem like it initially, but there is a lot going on with these complex pieces of anatomy! These multi-faceted structures play an important role in several different plant functions, including water and nutrient transport, gas exchange, structural integrity, and new growth. Each twig has a variety of different organs present to be able to perform these duties; check it out! First, lets take a glance at a few twigs from different species, then we can break down what we are looking at. At the very tip of a twig, you can find the terminal or apical bud, enclosed within bud scales for protection. This is where the newest growth of this branch or twig happens. You may find similar, smaller structures to the sides of this and along the stem in areas known as axils. These are the axillary buds; from these buds, a plant may develop smaller vegetative or reproductive shoots. Just below each axillary bud, there is the leaf scar (or a leaf, depending on the plant and time of year), on the node where the leaf once was attached to the branch. The spaces between each node are called internodes. Within each leaf scar, notice the very small pores. These are the vascular bundle scars, the remnant of the vascular structures which once ran to and from the leaf. Following a twig lengthwise, you may notice how it maybe segmented by annular rings. These rings are the bud scale scars, what’s left from last year’s apical bud, and the space between each represents one year’s growth. All along the twig, look for small pores called lenticels. These help to provide gas exchange through the thick, protective bark that covers the woody parts of plants. And that’s just on the surface! Inside each twig are layers of protective tissues, photosynthetic tissues, structural tissues, and vascular tissues, all highly organized and intricately connected for maximum efficiency. So, next time you are picking up sticks in your yard, playing fetch with your dog, or just snapping twigs while you idle, try to remember what complex pieces of biological machinery it is that you are handling! |
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