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)
This is actually not a gall as other answers have suggested.
This is likely a fungus called Cedar-apple rust (Gymnosporangium juniperi-virginianae).
The fungus only thrives in the presence of both Juniperus virginiana (Eastern red cedar) and apple (Malus spp.) trees.
The leaf in the picture belongs to some species of the apple genus and the growths are ...
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 ...
Turns out this is harder than it seems from just the picture...
The three candidates I think one could most argue for are:
Quaking Aspen (Populus tremuloides)
Paper Birch (Betula papyrifera)
Grey Birch (Betula populifolia)
Here is a picture of Populus tremuloides from the USDA:
Notice the smoothness of the above Aspen bark (identical to that of the ...
This looks like Muntingia calabura, the Jamaica Cherry.
It is indigenous to tropical America and often planted in Asia.
It is edible and used in jam, cake and fruit drinks. The bark is sometimes used as rope. Source: "Tropische vruchten, Nowak&Schulz 1999"
It is protection against rapid warming of the cambium layer. A lot of far northern timber has light colored bark which reflects sunlight. The rapid heating from very cold after sunrise can actually damage or even split the bark of dark colored species. This is called sunscalding.
This is very likely some species of Viburnum.
Viburnum is a genus of about 150–175 species of shrubs in the Adoxaceae family that are primarilly native throughout the temperate Northern Hemisphere.
All species of viburnum (as far as I know) have opposite leaves, as does the specimen in the picture.
Many species of Viburnums bloom in white in the last ...
Plu Code 4413 is a bosc pear (a cultivar of Pyrus communis).
From the PLU search tool available via the International Federation for Produce Standards
FYI: take a close look at the pear you're holding in your picture:
Pera canela, meaning "cinnamon pear" in English, is in reference to its color. From Wikipedia:
Famous for its warm cinnamon color
Possibly an example of a "Witch's Broom."
Witch's Broom is a deformity in plants (typically woody species) which typically causes dense patches of stems/shoots to grow from a single point on the plant. The name comes from the broom-like appearance of the stems.1
Witch's broom may be caused by many different types of organisms, including fungi, ...
Pretty interesting question: The short answer to it is: Yes, the seasonal O2 levels vary with the season and this can be measured.
The paper in reference 1 says that this is connected to two phenomena: Production of O2 by photosynthesis and also the uptake and release of O2 in the oceans due to higher temperatures (warmer water dissolves less gases).
This is a Birch tree, Betula sp., probably B. pendula, a common species in Denmark that also has hanging branches. It can be identified by the white bark and the leaves, that are not as long as a willow.
This question is too broad. What type of temperate forest?
The European Environment Agency recognized dozens of temperate forest types:
Acidophilous oak and oak‑birch forest types
Mesophytic deciduous forest types
Beech forest types
Mountainous beech forest types
Broadleaved evergreen forest types
Floodplain forest types
Non‑riverine alder, birch or aspen ...
Your pictures are a bit vague, but I think recognize Euonymus europeus, the spindle tree. So I assume the picture comes from Europe? The fruits are encapsulated in pink capsule, the fruit itself is bright orange.
It looks like a Purging Buckthorn (Rhamnus cathartica) - Native to Europe and North Asia. It is the food-plant of the Brimstone butterfly.
See Woodland Trust
If it is isolated from others perhaps it is rarely pollinated and never produces berries.
It is unusual to see such a large ...
Mangrove swamp trees and shrubs immediately spring to mind. There are many species that fall into this category of trees that grow in intertidal and costal locations. They prefer locations where salt and freshwater mix, known as 'brackish water'.
All roots require oxygen and the species that fall into this category have developed roots that protrude above ...
This is a tulipwood tree, which belongs to the species Harpullia pendula. As an Australian native, they're commonly used as street trees along the east coast.
More information about this tree can be found here.
For most trees and plants, distribution is spatially highly variable. Thinking about the lifecycle of plants—their seeds are non-randomly dispersed, the seedlings and saplings grow in different biotic (neighboring trees, distance to herbivores) and abiotic (different soils, shading, etc.) environments, all the plants are at different life/size stages, and ...
It is difficult to say, but it is likely due to disease. Many plant diseases have the effect of convincing plant tissues that they are some other organ than what they actually are, which leads to deformations.
I was not able to find anything that looked as dramatic as the image that you show, but there are similar diseases in stone fruits that deform fruit:
Based on the location and assuming this isn't a domesticated hazelnut there are two likely hazelnut species. The lack of the distinctive "beak" seen on the Beaked hazelnut means this is most likely an American hazelnut (Corylus americana):
The hairs along the young branch are also consistent with this (see for example the Plant Guide from the USDA).
A good first step is to pay attention to common differences between tree structure:
1. Alternate vs. Opposite structure
MADHORSE = your common eastern US opposite-leaved trees are Maple, Ash, Dogwood, and Horsechestnut (AKA buckeye).
2. Simple vs. compound leaves
3. Toothed ("entire") vs. untoothed leaves
4. Lobed vs. unlobed leaves
5. Differences in ...
Forest Succession 101
Pines are actually fast-growing, shade-intolerant, early-successional species. When land is allowed to lay fallow after being cleared by fire, wind storms, human land use or other major disturbance, the successional sequence will begin.
At first only herbs and grasses grow, but eventually these are shaded out by shrubs and tree ...
I think this is a Canistel (Pouteria campechiana):
The fruit are yellow when when ripe, but the form and also the leaves look very similar. The fruit are edible raw, you can find some more information here.
This looks like dried cholla cactus, although it will be hard to determine the species. It is sold commonly for fishtanks, so might even be found in places where it does not grow naturally if someone cleaned out their fish tank.
EDIT by Ilan: on this image you can clearly see that the tree identified right:
This is very likely a London planetree (Platanus × acerifolia), a hybrid species of Platanus often planted in cities.
Source: Cuyamaca College
The tree is a hybrid between Platanus orientalis and Platanus occidentalis (the sycamore tree), and has characteristics intermediate between the two species.
Smaller (heights of only 20-30 m ...
I'm going to take a stab here. It looks a lot like Artocarpus altilis or breadfruit. However, the trunk is a bit gnarly for breadfruit, but maybe that is the result of being a street tree. Also, I can't find any reliable information about the variation in the leaves (heterophylly) for this species. However, other species in the genus have entire leaves, ...
Not all seeds need to be ingested in order to be spread from one place to the other, in fact some won't grow at all if eaten, some need the fruit to help them germinate and sprout after they hit the ground. Nuts simply will not grow at all if you crack them open.
Most plants rely on the wind to disperse their pollen and seed.
Dandelions are a prime ...
These are definitely some sort of aphid (small sap-sucking true bugs in the superfamily Aphidoidea).
Based on the coloration and shape of the pest and the host plant, my best guess is that you're looking at Hyalopterus pruni (or the Mealy Plum Aphid).
Note: the scientific name of this species has changed at least 21 times!
Photo by Jack Kelly Clark