Posted by Amber Eaton.
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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 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 |
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