Help Identifying Tree

Help Identifying Tree

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I live in the upper southeastern region of Arizona in U.S. There's a type of tree growing in my back yard that I can't seem to identify. Its growing in an arrangement very similar to an ocotillo plant. It has single spiny stems coming up out of the ground. They don't branch out but have large sharp spines with leafs growing out of them. It doesn't look anything at all like any of the native desert plants in the area. There's mesquite and sage and various types of cactus.

At the moment the stems are about five feet tall. I took clippings about two feet in length and photographed them. It seems I'm only able to post two links so I've chosen the clearest images that I have. I'm very curious as to what this is and any help would be greatly appreciated.

It looks like this could be Lotebush, Ziziphus obtusifolia. The thorny branchlets and blue-green color (at least, as it appears in the photos) suggest Ziziphus to me, although you could compare it with the photos or description here. If it is in the buckthorn family, it does seem to key out to Ziziphus using the Christie et al. key.

If you wanted to be sure, you could follow up with the ASU herbarium (see citation).

Christie, K., M. Currie, L.S. Davis, M.-E. Hill, S. Neal and T. Ayers (2006). Vascular Plants of Arizona: Rhamnaceae. Canotia 2(1): 23-46. Open access

Biology 171

By the end of this section, you will be able to do the following:

  • Compare homologous and analogous traits
  • Discuss the purpose of cladistics
  • Describe maximum parsimony

Scientists must collect accurate information that allows them to make evolutionary connections among organisms. Similar to detective work, scientists must use evidence to uncover the facts. In the case of phylogeny, evolutionary investigations focus on two types of evidence: morphologic (form and function) and genetic.

Two Options for Similarities

In general, organisms that share similar physical features and genomes are more closely related than those that do not. We refer to such features that overlap both morphologically (in form) and genetically as homologous structures. They stem from developmental similarities that are based on evolution. For example, the bones in bat and bird wings have homologous structures ((Figure)).

Notice it is not simply a single bone, but rather a grouping of several bones arranged in a similar way. The more complex the feature, the more likely any kind of overlap is due to a common evolutionary past. Imagine two people from different countries both inventing a car with all the same parts and in exactly the same arrangement without any previous or shared knowledge. That outcome would be highly improbable. However, if two people both invented a hammer, we can reasonably conclude that both could have the original idea without the help of the other. The same relationship between complexity and shared evolutionary history is true for homologous structures in organisms.

Misleading Appearances

Some organisms may be very closely related, even though a minor genetic change caused a major morphological difference to make them look quite different. Similarly, unrelated organisms may be distantly related, but appear very much alike. This usually happens because both organisms were in common adaptations that evolved within similar environmental conditions. When similar characteristics occur because of environmental constraints and not due to a close evolutionary relationship, it is an analogy or homoplasy. For example, insects use wings to fly like bats and birds, but the wing structure and embryonic origin is completely different. These are analogous structures ((Figure)).

Similar traits can be either homologous or analogous. Homologous structures share a similar embryonic origin. Analogous organs have a similar function. For example, the bones in a whale’s front flipper are homologous to the bones in the human arm. These structures are not analogous. A butterfly or bird’s wings are analogous but not homologous. Some structures are both analogous and homologous: bird and bat wings are both homologous and analogous. Scientists must determine which type of similarity a feature exhibits to decipher the organisms’ phylogeny.

This website has several examples to show how appearances can be misleading in understanding organisms’ phylogenetic relationships.

Molecular Comparisons

The advancement of DNA technology has given rise to molecular systematics , which is use of molecular data in taxonomy and biological geography (biogeography). New computer programs not only confirm many earlier classified organisms, but also uncover previously made errors. As with physical characteristics, even the DNA sequence can be tricky to read in some cases. For some situations, two very closely related organisms can appear unrelated if a mutation occurred that caused a shift in the genetic code. Inserting or deleting a mutation would move each nucleotide base over one place, causing two similar codes to appear unrelated.

Sometimes two segments of DNA code in distantly related organisms randomly share a high percentage of bases in the same locations, causing these organisms to appear closely related when they are not. For both of these situations, computer technologies help identify the actual relationships, and, ultimately, the coupled use of both morphologic and molecular information is more effective in determining phylogeny.

Why Does Phylogeny Matter? Evolutionary biologists could list many reasons why understanding phylogeny is important to everyday life in human society. For botanists, phylogeny acts as a guide to discovering new plants that can be used to benefit people. Think of all the ways humans use plants—food, medicine, and clothing are a few examples. If a plant contains a compound that is effective in treating cancer, scientists might want to examine all of the compounds for other useful drugs.

A research team in China identified a DNA segment that they thought to be common to some medicinal plants in the family Fabaceae (the legume family). They worked to identify which species had this segment ((Figure)). After testing plant species in this family, the team found a DNA marker (a known location on a chromosome that enabled them to identify the species) present. Then, using the DNA to uncover phylogenetic relationships, the team could identify whether a newly discovered plant was in this family and assess its potential medicinal properties.

Building Phylogenetic Trees

How do scientists construct phylogenetic trees? After they sort the homologous and analogous traits, scientists often organize the homologous traits using cladistics . This system sorts organisms into clades: groups of organisms that descended from a single ancestor. For example, in (Figure), all the organisms in the orange region evolved from a single ancestor that had amniotic eggs. Consequently, these organisms also have amniotic eggs and make a single clade, or a monophyletic group . Clades must include all descendants from a branch point.

Which animals in this figure belong to a clade that includes animals with hair? Which evolved first, hair or the amniotic egg?

Clades can vary in size depending on which branch point one references. The important factor is that all organisms in the clade or monophyletic group stem from a single point on the tree. You can remember this because monophyletic breaks down into “mono,” meaning one, and “phyletic,” meaning evolutionary relationship. (Figure) shows various clade examples. Notice how each clade comes from a single point whereas, the non-clade groups show branches that do not share a single point.

What is the largest clade in this diagram?

Shared Characteristics

Organisms evolve from common ancestors and then diversify. Scientists use the phrase “descent with modification” because even though related organisms have many of the same characteristics and genetic codes, changes occur. This pattern repeats as one goes through the phylogenetic tree of life:

  1. A change in an organism’s genetic makeup leads to a new trait which becomes prevalent in the group.
  2. Many organisms descend from this point and have this trait.
  3. New variations continue to arise: some are adaptive and persist, leading to new traits.
  4. With new traits, a new branch point is determined (go back to step 1 and repeat).

If a characteristic is found in the ancestor of a group, it is considered a shared ancestral character because all of the organisms in the taxon or clade have that trait. The vertebrate in (Figure) is a shared ancestral character. Now consider the amniotic egg characteristic in the same figure. Only some of the organisms in (Figure) have this trait, and to those that do, it is called a shared derived character because this trait derived at some point but does not include all of the ancestors in the tree.

The tricky aspect to shared ancestral and shared derived characters is that these terms are relative. We can consider the same trait one or the other depending on the particular diagram that we use. Returning to (Figure), note that the amniotic egg is a shared ancestral character for the Amniota clade, while having hair is a shared derived character for some organisms in this group. These terms help scientists distinguish between clades in building phylogenetic trees.

Choosing the Right Relationships

Imagine being the person responsible for organizing all department store items properly—an overwhelming task. Organizing the evolutionary relationships of all life on Earth proves much more difficult: scientists must span enormous blocks of time and work with information from long-extinct organisms. Trying to decipher the proper connections, especially given the presence of homologies and analogies, makes the task of building an accurate tree of life extraordinarily difficult. Add to that advancing DNA technology, which now provides large quantities of genetic sequences for researchers to use and analzye. Taxonomy is a subjective discipline: many organisms have more than one connection to each other, so each taxonomist will decide the order of connections.

To aid in the tremendous task of describing phylogenies accurately, scientists often use the concept of maximum parsimony , which means that events occurred in the simplest, most obvious way. For example, if a group of people entered a forest preserve to hike, based on the principle of maximum parsimony, one could predict that most would hike on established trails rather than forge new ones.

For scientists deciphering evolutionary pathways, the same idea is used: the pathway of evolution probably includes the fewest major events that coincide with the evidence at hand. Starting with all of the homologous traits in a group of organisms, scientists look for the most obvious and simple order of evolutionary events that led to the occurrence of those traits.

Head to this website to learn how researchers use maximum parsimony to create phylogenetic trees.

These tools and concepts are only a few strategies scientists use to tackle the task of revealing the evolutionary history of life on Earth. Recently, newer technologies have uncovered surprising discoveries with unexpected relationships, such as the fact that people seem to be more closely related to fungi than fungi are to plants. Sound unbelievable? As the information about DNA sequences grows, scientists will become closer to mapping the evolutionary history of all life on Earth.

Section Summary

To build phylogenetic trees, scientists must collect accurate information that allows them to make evolutionary connections between organisms. Using morphologic and molecular data, scientists work to identify homologous characteristics and genes. Similarities between organisms can stem either from shared evolutionary history (homologies) or from separate evolutionary paths (analogies). Scientists can use newer technologies to help distinguish homologies from analogies. After identifying homologous information, scientists use cladistics to organize these events as a means to determine an evolutionary timeline. They then apply the concept of maximum parsimony, which states that the order of events probably occurred in the most obvious and simple way with the least amount of steps. For evolutionary events, this would be the path with the least number of major divergences that correlate with the evidence.

Art Connections

(Figure) Which animals in this figure belong to a clade that includes animals with hair? Which evolved first, hair or the amniotic egg?

(Figure) Rabbits and humans belong in the clade that includes animals with hair. The amniotic egg evolved before hair because the Amniota clade is larger than the clade that encompasses animals with hair.

(Figure) What is the largest clade in this diagram?

(Figure) The largest clade encompasses the entire tree.

Free Response

Dolphins and fish have similar body shapes. Is this feature more likely a homologous or analogous trait?

Dolphins are mammals and fish are not, which means that their evolutionary paths (phylogenies) are quite separate. Dolphins probably adapted to have a similar body plan after returning to an aquatic lifestyle, and, therefore, this trait is probably analogous.

Why is it so important for scientists to distinguish between homologous and analogous characteristics before building phylogenetic trees?

Phylogenetic trees are based on evolutionary connections. If an analogous similarity were used on a tree, this would be erroneous and, furthermore, would cause the subsequent branches to be inaccurate.

Describe maximum parsimony.

Maximum parsimony hypothesizes that events occurred in the simplest, most obvious way, and the pathway of evolution probably includes the fewest major events that coincide with the evidence at hand.


Leafsnap: An Electronic Field Guide

Leafsnap is a series of electronic field guides being developed by researchers from Columbia University, the University of Maryland, and the Smithsonian Institution. The free mobile apps use visual recognition software to help identify tree species from photographs of their leaves. They contain beautiful high-resolution images of leaves, flowers, fruits, petioles, seeds and bark.

The original Leafsnap currently includes trees found in the Northeastern United States and Canada, and will soon grow to include the trees of the entire continental United States. The high-resolution images in the original app were created by the conservation organization. Finding Species.

This website shows the tree species included in Leafsnap, the collections of its users, and the team of research volunteers working to produce it.

The Leafsnap UK app includes trees from the United Kingdom with species information and imagery provided by the Natural History Museum in London. More information can be found on the Natural History Museum website.

The City College of New York developed and tested curricular materials that use the Leafsnap app to help middle school students notice, group, and contextualize street trees in the patterns of evolution. Curricular guide and other educational materials are available from here.


You have found an opposite arrangement.

The next step is to look more closely at a single leaf to determine if it is compound or simple. This has more to do with the structure of the leaf itself than with the position of the leaf on the stem. One of the defining characterstics of a leaf is that at the base of the leaf stem (petiole) there is a small bud called the axillary bud. Sometimes this bud is covered by the petiole so make sure you look carefully.

If there is no axillary bud at the base of the petiole, then the structure is not a leaf but rather a leaflet and the leaf, as a whole, is compound.

Introduction to Phylogeny:What is a Sister Taxon?

In this example, note that terminal nodes snake and lizard are sister taxa. The branches leading to them meet at node 1 (red arrow) to form clade a (red bracket). Likewise, bird and crocodile are sister taxa. They are members of clade b who share a common ancestor, node 2, that lived more recently than their last common ancestor shared with clade a, which is at node 3. According to this cladogram, a bird or crocodile are equally closely related to a lizard (or a snake), because they are related by way of the common ancestor at node 3. Note also that clade a and clade b are sister taxa. One way to think about this is to consider the snip rule for dividing clade c into the daughter lineages derived from the common ancestor at node 3. Imagine traveling up each branch from node 3 only a short distance before snipping. What falls off are the sister taxa: clade a and clade b.

For practice, can you answer the following questions? What is the sister taxon of the turtle? (*). Which node is the last shared common ancestor of mammal and lizard? (*) *You should have answered clade c and node 5, respectively. Go Back

Simple ID key

Want to know what that plant is? With our Simple Key, you can identify over 1,200 common native and naturalized New England plants! Observe closely, collect a sample or take a photo, answer some questions, and narrow down to the correct identification.


Connect with other plant fans

Join our online community of plant enthusiasts. Find friends, share your plant sightings, get help with plant identification, collaborate on field surveys, and develop checklists of plants for particular sites you are exploring.

Advanced ID tools

For experienced botanists

Identify over 3,000 New England plants by using either our multiple-access Full Key or our Dichotomous Key to families, genera, and species. Also learn about subspecies and varieties native to our region.

Teaching tools

Useful teaching resources

Go Botany encourages informal, self-directed education in botany for science students, and beginning and amateur botanists. Professors, teachers, and environmental educators can share curricula and teaching ideas.

Plant of the day: Euphrasia stricta strict eyebright

Strict eyebright is an introduced European annual that is widely used for its medicinal properties. It is hemiparasitic (partially parasitic, stealing nutrients from the roots of another plant but also using photosynthesis to make its own). Its host plant, yellow bedstraw ( .

Please contribute to our mission to conserve and promote the region’s plants by donating to Native Plant Trust. Donate

All images and text © 2021 Native Plant Trust or respective copyright holders. All rights reserved.

Native Plant Trust
180 Hemenway Road
Framingham , Massachusetts 01701 USA

The Go Botany project is supported in part by the National Science Foundation.



Phylogenetic trees have become a standard tool in the study of adaptation, and such uses are often referred to as the “comparative method.” First, it is necessary to establish that a particular “adaptation” is distributed as an apomorphy within the group in question and then, if there are multiple origins, to determine if these origins are correlated with other characters and/or environmental variables. While numerous statistical approaches have been suggested for such studies, they all assume that multiple independent origins of characters correlated with environmental or historical factors are evidence of adaptation. Indeed, some workers maintain that it is only possible to discuss adaptation in a historical context, i.e., based on explicit phylogenetic trees. Undoubtedly continued work in these areas will result in improved statistical tests for adaptation based on character distributions on phylogenetic trees.

What Can Trees Tell Us About Climate Change?

But to understand what the trees tell us, we first have to understand the difference between weather and climate.

Weather is a specific event—like a rain storm or hot day—that happens over a short period of time. Weather can be tracked within hours or days. Climate is the average weather conditions in a place over a long period of time (30 years or more).

Scientists at the National Weather Service have been keeping track of weather in the United States since 1891. But trees can keep a much longer record of Earth’s climate. In fact, trees can live for hundreds—and sometimes even thousands—of years!

One way that scientists use trees to learn about past climate is by studying a tree’s rings. If you’ve ever seen a tree stump, you probably noticed that the top of the stump had a series of rings. It looks a bit like a bullseye.

The light and dark rings of a tree. Image credit: Flickr Creative Commons user Amanda Tromley

These rings can tell us how old the tree is, and what the weather was like during each year of the tree’s life. The light-colored rings represent wood that grew in the spring and early summer, while the dark rings represent wood that grew in the late summer and fall. One light ring plus one dark ring equals one year of the tree’s life.

The color and width of tree rings can provide snapshots of past climate conditions.

Because trees are sensitive to local climate conditions, such as rain and temperature, they give scientists some information about that area’s local climate in the past. For example, tree rings usually grow wider in warm, wet years and they are thinner in years when it is cold and dry. If the tree has experienced stressful conditions, such as a drought, the tree might hardly grow at all in those years.

Scientists can compare modern trees with local measurements of temperature and precipitation from the nearest weather station. However, very old trees can offer clues about what the climate was like long before measurements were recorded.

This is said to be the Methuselah Tree, one of the oldest living trees in the world. Methuselah, a bristlecone pine tree in White Mountain, California is thought to be almost 5,000 years old. Image credit: Oke/Wikimedia Commons

In most places, daily weather records have only been kept for the past 100 to 150 years. So, to learn about the climate hundreds to thousands of years ago, scientists need to use other sources, such as trees, corals, and ice cores (layers of ice drilled out of a glacier).

Do you have to cut down a tree to see the rings?

No way! You can count the rings of a tree by collecting a sample with an instrument called an increment borer. The borer extracts a thin strip of wood that goes all the way to the center of the tree. When you pull the strip out, you can count the rings on the strip of wood and the tree is still as healthy as can be!

A student learns how to take a tree core sample with an increment borer in the Manti-LaSal National Forest in Utah. Image credit: USDA

Biology Lesson Plans

Coffee: How does a Coffee Bean Become a Cup of Java?

Bird Songs: What Is a Bird Saying When It Sings

High Jump: How Do High Jumpers Set New Records?

Reflexes: Why Does a Doctor Check My Reflexes When I Have a Check-Up?

Taste and Smell: Why Does Food Seem Tasteless When You Have a Cold?

Bone Marrow: What Is a Bone Marrow Transplant and How Does It Work?

Bones: How Do Bones Get So Strong?

DNA Fingerprinting: Can Blood Found at a Crime Scene Really Identify a Criminal?

Fingerprints: A Lesson in Classification

Hearing: Can I Damage My Hearing by Listening to Loud Music?

High Jump: How Do High Jumpers Set New Records?

Hip Replacement: How Do Artificial Implants Work in the Body?

Jungle Survival: How Do People Survive in the Jungle without Food or Water?

Malaria Tracking: How Can You Locate Disease-Carrying Mosquitoes?

Murder Mystery: How Do Forensic Scientists Help Solve Murders?

Nicotine: Why Is It So Hard to Quit Smoking?

Olympic Training Center: How Can Biomechanics Help an Athlete?

AIDS: What Is Acquired Immune Deficiency Syndrome?

Balloon Safari: How Does the Mara Ecosystem in Africa Work?

Bird Songs: What Is a Bird Saying When it Sings?

Blood Typing: What Makes Different Blood Types Different?

Bone Marrow: What Is a Bone Marrow Transplant and How Does it Work?

Bones: How Do Bones Get So Strong?

Coffee: How Does a Coffee Bean Become a Cup of Java?

DNA Fingerprinting: Can Blood Found at a Crime Scene Really Identify a Criminal?

Fingerprints: A Lesson in Classification

Hearing: Can I Damage My Hearing by Listening to Loud Music?

High Jump: How Do High Jumpers Set New Records?

Hip Replacement: How Do Artificial Implants Work in the Body?

In-Vitro Fertilization: What are "Test-Tube Babies" and How are They Made?

Jungle Survival: How Do People Survive in the Jungle without Food or Water?

What to Do for a Sick Tree

If your tree has you asking “What does a dying tree look like?”, and “Is my tree dying?”, the best thing you can do is call an arborist or a tree doctor. These are people who specialize in diagnosing tree diseases and can help a sick tree get better.

A tree doctor will be able to tell you if what you are seeing on a tree is signs that a tree is dying. If the problem is treatable, they will also be able to help your dying tree get well again. It may cost a little money, but considering how long it can take to replace a mature tree, this is only a small price to pay.

Watch the video: αγοράζεται και φυτεύεται στο σπίτι, το δέντρο συμβολίζει την αγνότητα και την - ВЛАДИМИР КАЗАКОВ (June 2022).


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