Information

What's up with this leaf?


This cool design was "tattooed" on this leaf.

I found it on the windshield of my car.

What's up with it?


That is the work of a leaf miner. A leaf miner is the larval stage of an insect that feeds on the inside layer of leaves. Notice how the galleries (tunnels) start small and then get larger as the larva matures? Most leaf miners are moth larvae (Lepidoptera) https://en.wikipedia.org/wiki/Leaf_miner


This leafminer is a moth in the genus Phyllocnistis (Gracillariidae). If you knew what plant the leaf came from, the moth could probably be identified to species. The marginal leaf fold at lower right is where the mature larva has spun its cocoon.

Incidentally, I'm just finishing a complete guide to the known leafminers of North America. There are many species left to be discovered though!


What's up with this leaf? - Biology

Photosynthesis is the process by which plants and other organisms (i.e. cyanobacteria and algae) convert light energy from the sun into chemical energy. In the process of photosynthesis, carbon dioxide (CO 2 ) and water (H 2 O) undergo a series of chemical reactions initiated by light energy to produce glucose (C 6 H 12 O 6 ) and oxygen gas (O 2 ).

As sunlight shines down on plants, water is absorbed by the root system of the plant. W ater is carried up by an internal plumbing system, known as the vascular tissue , up to the photosynthetic tissue (i.e. the leaves).

In the leaves, water brought up from the vascular tissue absorbs into the photosynthetic leaf cells via simple or facilitated diffusion. Carbon dioxide (a gas) diffuses into the leaf directly through specialized mouth-shaped cells, known as guard cells. The holes made by guard cells are called stomata. Carbon dioxide and water go through a series of chemical reactions in the chloroplasts of plants to produce glucose with oxygen as a byproduct.

In the leaf of the plant, there are several different tissues. The upper and lower most tissues are composed of small, boxed-shaped cells known as the epidermis . These cells excrete a waxy substance on the outside of the epidermis, known as a cuticle. The cuticle’s function is to prevent water loss in plants. Cuticles are so effective at preventing water loss, plants had to develop a mechanism for getting carbon dioxide gas into the leaf. Guard cells are able to open and close and are responsible for regulating the plant’s CO 2 and H 2 O levels.

Cross Section of a Leaf.

Inside the leaf are two other photosynthetic tissues. Just below the upper epidermis is a layer of tightly packed photosynthetic cells that undergo the majority of photosynthesis in plants, the palisade mesophyll. Directly below this layer are photosynthetic cells that are much more spread out, known as the spongy mesophyll. When the guard cells close to conserve water, this layer serves as a CO 2 reservoir, which allows photosynthesis to continue even in a closed system. That is, until all of the CO 2 is fixed.

Water is absorbed by the roots of the plant and travels up the vascular system by the tissue known as xylem. Water enters the leaf and absorbs into the photosynthetic cells by osmosis, combining with CO 2 to produce glucose and oxygen. Inside the cell, water can be stored in the vacuole .Excess oxygen not used during cellular respiration diffuses to the outside environment via diffusion. Glucose is either utilized by the cell directly, or is shuttled to the vascular tissue that transports glucose to other cells incapable of photosynthesis (i.e. roots) in a vascular tissue known as phloem.


Learn about Leaves

A leaf is a flat, thin plant organ that uses the sun to make its own food. In general leaves are green and use the chemical called chlorophyll to trap energy from the sun. This process is known as Photosynthesis. The energy is used to combine water from the soil and carbon dioxide gas from the air to make sugar. Oxygen is released during this process a process called Respiration. The leaf acts almost like a solar panel for attracting energy from the sun. Leaves are prominent in the human diet as leaf vegetables like lettuce.You may not realize it but we eat some form of leaf almost every day…well I know I do!

What are the types of leaves?

Most leaves are flat to increase absorption from the sun although this is not always the case. The main flat area is called the blade or lamina. Not all leaves are flat but most are. A simple leaf has an undivided blade. A compound leaf has a fully subdivided blade with is separated by a main or secondary vein.

What is a plant?

A living thing that usually can produce its own food, reproduces, and rarely is able to move by itself. Many (although not all) plants are green and are part of our ecosystem. A plant is what the leave is attached to.

What are the parts of a plant?

The plant is made up of three parts:

The Leaves – are basically a food making machine.

The Stems – The stems are the plant’s support system. Stems hold up leaves to the light and keep fruits and flowers attached. They grow straight up, trail along the ground, climb fences and trees or stay underground.

The Roots – the roots are the plants anchor and hold the plant firmly in the ground. Roots are also absorbers of water and minerals from the soil. They also store minerals.

What are the parts of a leaf?

There is awesome variety in leaf structure and some may have all or few of the following parts. The main flat area is called the blade or lamina. Small processes located to either side of the base of the petiole are called the stipule. In some leaves there is no stipule for example. Nearly every leaf has a leaf stalk. The leaf stalk is called the petiole. The petiole attaches to the stem at a point called the leaf axil. Leaves can store food, water and minerals and these are transported through the veins and stem.

What are the layers of a leave?

A leaf is made up of three layers:

Epidermis – This is the outer layer of cells covering the leaf. It is usually transparent and is waxy to prevent water loss.

Mesophyll – This is the interior of the leaf between upper and lower epidermis. This is where most of the photosynthesis occurs. The Mesophyll is divided into two layers a) The upper palisade layer which is tightly packed. Beneath the palisade layer is the b) spongy layer which is, you’ve guessed it…spongy!

Veins – The blackish lines in the leaf blade are called veins. The largest black line is the leaf’s single “midvein,” running from the petiole to the leaf tip, the smaller blackish lines branching off the midvein are “secondary veins”.Veins lend support to the leaf tissue, helping it keep its shape, just like the ribs in an umbrella. Veins also move substances within the leaf, rather like the veins in our own bodies move blood.

Why do leaves change color?

Chlorophyll is the chemical in leaves that make them green in color. In spring and summer, when there is lots of sunlight, this chemical absorbs energy from the sun and turns it into carbon dioxide and water into sugar and starch.

However, during the fall and winter when there isn’t much sunlight the leaves stop making food and the chlorophyll breaks down making the green color disappear. The other color of the leaves begin to show such as red, orange, yellow and gold. As the leaf is changing colors, the stem is also changing.

Where it is attached at the tree (leaf axil) the cells supporting the leaf are cut. When the wind blows or if the stem is dry, the leaf falls to the ground. That’s why the trees become bare in autumn! Trees that lose there leaves after changing color are called deciduous trees for example oak, maple, birch and elm.


It’s time to leaf: comparing monocot and dicot leaves

The leaves of flowering plants have an upper and lower surface, with the upper surface generally facing away from the ground and the lower surface facing toward it.

Leaf dermal tissue

Both monocot and dicot leaves have an outer, waxy layer called the cuticle that covers the dermal tissue of the upper and lower epidermis. The cuticle protects the leaf and helps it retain water. The epidermis, which is located beneath the cuticle, also protects the leaf. It plays a key role in gas exchange as well, because it contains pores called stomata. Stomata are also present in the plant’s stem and flowers, to some extent, but they are primarily a feature of the leaves.

The stomata allow carbon dioxide to enter the leaf and provide an avenue for water vapor and oxygen to exit the leaf. Each stoma is bordered by two specialized parenchymal cells, called guard cells. These cells open and close the stoma. When the turgor pressure in the guard cells is high, they bend outward, causing the stomatal pore to open. When the turgor pressure in the guard cells is low, due to a loss of water, the stomatal pore is closed.

Leaf ground tissue

A type of ground tissue called mesophyll fills the area between the leaf’s upper and lower epidermis. The cells in the mesophyll contain numerous chloroplasts, organelles that carry out photosynthesis, converting light, water, and carbon dioxide into sugar the plant can break down to generate energy. Oxygen is the main byproduct of photosynthesis—which is great for organisms like humans who need oxygen to breathe!

Leaf vascular tissue

In monocot and dicot leaves, vascular bundles are surrounded by one or more layers of parenchyma cells known as bundle sheaths. They protect the “veins” of the leaf. In monocot leaves, the cells of the bundle sheath carry out photosynthesis, but this isn’t always the case in dicot leaves.

Both types of vascular tissue have an important role to play in leaves. The xylem brings water and dissolved minerals up from the roots, and the cells in the mesophyll use the water when carrying out photosynthesis. Excess water is expelled through transpiration, the release of water vapor through the stomata. The phloem takes the dissolved sugars created by photosynthesis to the plant’s stem and roots to be used or stored.


31 Best Biology Pick Up Lines - Spark amazing conversations.

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After all, what could be more romantic than biology? Seriously though, biology is a great subject, whether you&rsquore looking for that cool ice breaker or a few fun pick up lines that&rsquoll get your crush&rsquos attention.

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Show off your science knowledge and flirting skills at the same time, and your crush just won&rsquot be able to say no.

If you need a little help with your biology pick up lines, all you need to do is continue reading. You&rsquoll find no shortage of awesome, cute, and funny ideas that&rsquoll provide real results.


Biological Fluids

Crime scene investigators hunt for evidence of a crime by using a black light and sometimes an added sprayed-on chemical to locate dried and cleaned up blood stains. Beneath a black light, blood turns black, unless sprayed with luminol which gives it a blue-glow. Saliva, semen and urine also glow when hit with a black light. Most biological fluids contain fluorescent molecules to help them glow. When hunting down that spot where Fido urinated, use a black light in a dark room to find and clean it instead of your nose.


4. Make Your Biology Resume Education Section Shine

Who cares about your education? Well, actually a lot of people do and it could make or break your chances of making it into the lab.

Here&rsquos how to nail your education section:

  • If you have several years of job experience opt for only listing the following: college/university name and location, years you studied, degree, major and minors.
  • Have limited experience? Sprinkle your education resume section with achievements from your college days. Make sure to keep them relevant to the job description and list no more than 4-6 items.

If you&rsquore a graduate as new as spring grass, consider putting your work experience below your education section. It&rsquoll help you start off your biology resume with no experience with a bang.

Studied abroad? Check how to put it on your biology resume: Studying Abroad on a Resume


Why Are My Plant Leaves Turning Yellow?

1. Not Enough Water

One of the most common causes of yellowing leaves is moisture stress. If your plant is not getting enough water, its leaves will start to droop so the plant can prevent excess transpiration. This conserves water.

Right before the leaves fall off the plant, they will turn yellow. If your plant is dry – you can stick your finger into the soil to check it – try to get it on a regular watering schedule.

Other signs that your plant is not getting enough water are leaves that are curling inward, drooping down, or becoming “crunchy”-looking.

2. Too Much Water

On the flip side, a plant that is receiving too much water can also face the threat of yellowing leaves. When soil does not drain well, it becomes heavy and waterlogged. The roots will essentially drown as they are deprived of oxygen. The leaves of the plant will yellow as a result.

To tell if your plant is overwatered, check the soil at an inch below the surface. If it feels damp there, it’s probably too wet. Check the plant for signs of root rot, which is usually signaled by a mildew-like smell.

If you think your plant might be overwatered, you will want to adjust your watering schedule and consider transferring the plant to a container that has better drainage in the meantime.

3. Transplant Shock

In many cases, a plant has yellowing leaves just because it is still getting settled into its new home. If you’ve just transplanted a plant or even just bought a new house plant home, you might find that the leaves turn yellow and stay that way for a while.

While it’s a good idea to keep an eye on these leaves, don’t panic right away. Give the plant some time to get adjusted before you do anything else.

Another common issue related to yellowing is root-binding. If the roots of the plant don’t have room to grow, they might become overcrowded and the leaves of the plant will yellow as a result. A plant that needs to be transplanted outdoors should be moved out and fertilized as soon as possible. If it’s a houseplant, repot it into a bigger container.

4. Chemicals or Minerals in the Water

If you are watering your plant with tap water, you might want to check to see if your water is actually safe for your plants to drink.

Sometimes, plants will have a sensitivity to the minerals and chemicals found in tap water, such as chlorine and fluoride. There are also trace salts found in water that can harm sensitive plants.

If you think this might be causing your plant’s yellowing leaves, simply fill the watering can up the night before you intend to water. Let it sit out on the counter, which will give the minerals time to evaporate. You can also water with distilled water or even collected rainwater.

5. Too Much or Too Little Light

Light is another factor, like water, that is incredibly difficult to manage. Plants that don’t get enough light will turn yellow on their lower leaves.

Plants that are getting too much light will appear somewhat scorched. Make sure you look up the exact lighting requirements of your plants – you might be surprised to learn that not all plants love being placed in direct sunlight for the entire day.

If you want to know whether light is the issue at play here, just closely examine the leaves. If a plant is suffering from a lack of light, it will yellow on the side pointed away from the light source. This is usually because the leaves closest to the light are blocking it.

Move the plant to a sunnier location (if it’s being grown indoors and this is possible) and see how it responds. You can also try putting up an artificial light.

6. Nutrient Deficiency

Nutrient deficiencies are also common culprits when it comes to yellowing leaves. Usually, that nutrient is nitrogen. If this is the issue, you will likely notice the top leaves turning yellow first, you might notice that the leaves develop an odd pattern in addition to the yellowing – they might develop dark veins, for instance, or the tissue between them might turn yellow.

If the yellowing issue is occurring on old leaves on your plant, while the new leaves are still relatively green, it is likely a sign of nitrogen deficiency. You will want to supplement with a nitrogen-based fertilizer. If that’s not the case, you’ll want to figure out what nutrients your plant is deficient in.

Nutrient requirements in a plant vary widely depending on the species – some are more selective than others. You might want to test your soil to see what it is lacking or has in excess.

Other common nutrient deficiencies include calcium and boron, so make sure your fertilizer has both of these if you suspect that is the problem.

You don’t always have to turn to synthetic fertilizers, either. Adding something as simple as Epsom salts to the soil around your plant can boost its magnesium content, as a lack of magnesium can lead to yellowing leaves, too.

7. Leaf Spot Disease

Leaf spot diseases are caused by either bacteria or fungus, both of which feed voraciously on the leaves of your plant. This disease causes the plant to turn yellow, but it’s usually a telltale yellowing. You shouldn’t have any doubt in your mind that it’s leaf spot disease and not anything else.

When your plants have a leaf spot problem, they will have tiny brown spots trimmed in yellow instead of an overall yellowing or a fading of their colors. You should prune the leaves and isolate the plant from the other greenery you have growing nearby, if possible.

Then, add a tablespoon of baking soda and a teaspoon of mineral oil into a spray bottle of water. Mist the leaves that are infected with the spots, and it should get rid of the bacteria. You may have to do this a few times to see results.

8. Fungus Gnats

If you notice that the soil surrounding your plant is especially wet – or if the base of the plant stem has turned black – fungus gnats could be to blame. These usually are a good sign that your plant is overwatered. The lower leaves typically drop down first, but you might find that the whole plant is affected.

Ease up on the watering to get rid of the gnats. You can also re-pot the plant to help reduce its susceptibility (if it’s being grown indoors).

There are other pests that occasionally target plants, too, but fungus gnats are the most common. You can usually see other types of pests, like spider mites or mealybugs, and you’ll typically notice signs of infestation besides yellow leaves.

For example, small holes throughout the leaves indicate that something is eating them – usually, that’s a sign of spider mites. If you see a fluffy substance that looks a bit like white wax on the plants, you’re dealing with mealybugs.

You might need to prune the infested leaves and remove the bugs by hand from the plant. You can also use natural insecticidal sprays and neem oil to get rid of the pests, too.

9. Temperature Issues

If you’re growing plants indoors, a cool draft can be the kiss of death. It will often cause the leaves to yellow and drop. Outdoor-grown plants won’t react to cold temperatures in the same way, as they usually will experience outright browning on their foliage due to more intense cold.

Yellowing leaves are usually related to temperatures that are too cold, but occasionally, temperatures that are too hot can cause your plant to become dry and yellowed-looking, too. Keep an eye on the temperature, and if it seems like your plant is getting dried out, consider misting it to boost the humidity.

Remember that temperature and moisture are closely related. Often, growing a plant in a location that is too cool or drafty can cause it to become waterlogged, too, as the plant won’t uptake water as efficiently. Therefore, by solving one of these issues, you may be able to take care of both at the same time.

10. Yellowing Leaves in Aging Plants is Normal

As some plants age, their leaves will turn yellow and fall off. Unfortunately, this is just a natural part of their growth and there’s not much you can do.

Plants that are grown for their foliage, like Dracaena, are particularly prone to this ailment. In some cases, you may be able to just trim back the main stem, which will promote new growth, or trim off the dying yellow leaves to make room for fresh new growth.


We won’t know the sex ratio of our young frogs for at least a year.

Ideally, we want to ensure all of the founder frogs have bred and their genes are represented in the population. So, our current plan is to continue breeding this species.

Eventually, as we raise the tadpoles and froglets to maturity, we will hopefully send them to other zoos for breeding. We might even have an opportunity in the future to send frogs to the Panama Amphibian Rescue and Conservation Project in Panama, which would be fantastic!


Ancient History and Succession

Given Earth’s loooong geologic history, our boreal forests are relative newcomers to the world biome scene. This is not to say coniferous forests like this haven’t existed before. They have. Just not where you would expect them to be. This is because throughout Earth’s climatic history, temperatures have fluctuated regularly, and glaciers have expanded and retracted over enormous distances. Approximately 20,000 years ago, when ice sheets were at their last glacial maximum, tundra and permafrost covered much of what is now boreal forest, and coniferous forests grew where we now see temperate deciduous forests. As the glaciers retreated, they literally paved the way for modern boreal forests.

Glaciers, Lakes, and Bogs

As the glaciers retreated north, they scraped and gouged the Earth below them, leaving behind vast expanses of tundra and landscapes pockmarked with deep depressions. The tundra eventually gave way to coniferous forests when the temperatures were right, and the depressions filled with water, forming thousands and thousands of glacial lakes. In the northern latitudes, a unique moss called sphagnum moss helped to drastically change the landscape.



Sphagnum moss is crazy awesome, y’all. It is most often found along the edges of lakes and bogs, where it absorbs an unbelievable amount of water. (One ounce of dry sphagnum can hold almost a pound of water!) As more and more sphagnum builds up around the lake, some of it dies and begins to decompose. Remember that decomposition is a slow process in the Boreal forest, due to acidic and oxygen-poor conditions. When sphagnum decomposes under these conditions it turns into peat, a rich organic sediment, which accumulates around the lake’s edges and fills in from below. When enough sphagnum moss and peat have displaced the water in a lake, it can be called a bog. When the peat layers displace all of the water in the bog, trees are able to take root, and eventually, boreal forest takes the place of the bog. The eventual succession from bog to forest can take a very long time because the soil conditions in a bog are even more acidic and oxygen-starved than the boreal forest. Due to the extreme acidity and low oxygen conditions in a bog, they usually host a very unique set of plants which are adapted to the most extreme conditions. Cranberries, lingonberries, and dwarf blueberries are small, tart berries that do well in these conditions, and can be a sweet treat for a bog-traveler, if they don’t get pulled down by subterranean marsh kings first!

Actually, marsh kings don’t really exist (as far as we know), but bogs can be dangerous places to wander if you aren’t careful. The real reason is the peat layers at the bottom of a bog can be deceptively deep. If you stepped in an area where the peat was not fully compact, you could end up sinking up to your waist, or deeper, and be unable to climb out.

Common Disturbances

Boreal forests are not as long lived as many old-growth deciduous forests. While many stands of boreal forest can reach a mature age, frequent disturbances often keep the forest from reaching late successional stages. Insects are one of the most common disturbances that keep these forests from getting too old. In North America, for example, Spruce Bark Beetles are responsible for killing millions of mature Spruce trees every year. The beetles dig their way in between the bark and wood of the tree, eating away the cambium layer. Eventually, the tree is unable to transport its nutrients and it dies. While the beetle attacks both young and old trees, young trees are able to defend themselves more readily than mature trees, and are less affected by beetle infestations. While beetle infestations are a natural component of the boreal forest, global climate change has allowed them to speed up their life cycle, and damage from beetle attacks has escalated as a result.

Fire is another common disturbance in the dry areas of a boreal forest. In this case, mature trees normally survive the blaze, but young trees and ground cover burn quickly, recycling their nutrients back into the soil. Working in tandem, these disturbances keep the forest young and healthy.