Trees

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My Review of Decurrent Trees

Just because it’s winter doesn’t mean there aren’t plenty of plants to look at. Deciduous trees and shrubs become particularly interesting during the winter months with their exposed branches and their growth habits made more obvious. The beauty of a tree’s “skeletal” structure is revealed when it’s stripped of its leaves and set against a winter sky. Winter is also a great time to prune certain trees and shrubs (when appropriate), partly because their branches are so easily viewed and “problem” areas readily reveal themselves. Whether you’re observing a tree’s branching structure simply for enjoyment-sake or because you plan to prune, you may find yourself noticing distinct differences in the growth habits of trees. Distinct growth habits can help you identify trees. They can also tell you something about a tree’s environment or growing conditions.

In the book, The Tree, Colin Tudge defines a tree as “a big plant with a stick up the middle.” Sometimes this “stick” runs straight up from the ground to the top of the tree without interruption and is the tallest portion of the plant. Other times, the “stick” reaches a certain height and branches out into multiple “sticks,” each one reaching out in a different direction – some heading more outward, while others continue to reach for the sky. This is the difference between excurrent and decurrent growth.

excurrent growth habit: dawn redwood (Taxodium distichum)

A tree with an excurrent growth habit has one central leader – or single trunk – that reaches all the way to the top of the tree. Side branches occur along the length of the trunk and generally get shorter as they move up the tree, producing a pyramidal or conical shape. Think of a typical Christmas tree. Many conifers exhibit excurrent growth, as do several deciduous trees such as sweetgum and pin oak, as well as aspens and other poplars. When a tree divides part way up the trunk, splitting into several large branches – none of which could be considered the dominant branch – it is exhibiting a decurrent growth habit. Trees that generally fall into this category include elms, maples, oaks, and ashes. The growth habit of a tree is largely a result of its genetics, but plants are known for their plasticity, taking on a wide variety of forms depending on their parentage and their circumstances. Trying to identify a tree based only its growth habit, isn’t likely to yield great results.

decurrent growth habit: oak (Quercus sp.)

The environment that a plant is growing in can have noticeable effects on the form the plant takes. A tree growing up in a forest thick with other trees will typically grow straight up in search of sunlight and will branch out very little until it can get up high enough to do so. That same species of tree growing in an open field might instead branch out extensively at a much lower height, taking advantage of the generous amount of space to stretch its branches out wide. As Tudge puts it in The Tree, “one form for the forest, another for the open ground.” Additionally, things can happen in a tree’s life that will drastically alter its form. If, for example, a storm comes through and breaks off a tree’s central leader, several side branches might grow out and upward to take its place, giving an otherwise excurrent tree a decurrent form. The pruning that humans often do (sometimes unwisely) to trees and shrubs, particularly in urban settings, can also alter a plant’s natural growth habit considerably. These are important considerations to make when assessing the forms of trees.

decurrent growth habit: golden rain tree (Koelreuteria paniculata)

I give decurrent growth habits five stars. No shade on excurrent trees. They’re also beautiful. But while trees with excurrent growth habits have otherwise predictable forms, decurrent trees are full of surprises. Their broad and rounded forms provided by their deliquescent branching structures are endlessly interesting, and their capacious canopies ensure that no two trees are alike.

decurrent growth habit: Malus sp. (I presume)

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Tea Time: Kentucky Coffeetree

Learning to identify Kentucky coffeetree in the winter brings you one step closer to making a coffee-like (albeit caffeine-free) beverage from its seeds. Humans have a long history of occasionally using the “beans” of Gymnocladus dioicus to make this tisane, which explains common names like coffeetree, American coffee berry, and coffeenut. The process is a bit time consuming, and the end result is mixed, but foraging adventures like this are all about the experience. This drink is not likely to replace whatever you are currently drinking in the morning, but it does offer an interesting diversion.

fruit of Kentucky coffeetree (Gymnocladus dioicus)

Winter is the best time to collect the pods, which are flat, leathery, brown to black in color, and about 2 inches wide and 6 inches long. The stocky fruits are often found hanging from the tips of the tree’s bare branches. Many also fall to the ground over the course of the season, making them easier to collect. If you split the pods open early in the season, you’ll find the seeds embedded in a sticky, neon green goo that will stick to your hands and clothes. As the year progresses, the glue-like substance dries out and is easier to deal with. The seeds are dark, extremely hard, rounded and flattened, and about the size of a penny or nickel. The funiculus, which is a short stalk that connects the ovule/seed to the ovary, tends to be fairly prominent and something you don’t often get to see on seeds.

inside the fruit of a Kentucky coffeetree

Once you’ve collected several pods and removed the seeds from the gooey innards, soak the seeds for an hour or two and then rinse them, making sure to remove dried up goo and any remaining funiculi. Pat the seeds dry and place them in a baking dish with a lid for roasting. The roasting process is said to eliminate the toxicity of the seeds. The lid is important because several of the seeds will pop open during roasting and will fly around in your oven if they aren’t contained.

The fruits of Kentucky coffeetree contain a toxic compound called cytisine, an alkaloid that is similar in action to nicotine. The Handbook of Poisonous and Injurious Plants by Nelson, et al. states that “the cytisine content of the seeds is quite low; and chewing one or two would not be expected to produce toxic effects.” Actually, the bigger risk of chewing one of these rock hard seeds is breaking your teeth. Cytisine poisoning includes typical symptoms like diarrhea and vomiting; in extreme cases it can lead to coma and death. If the seeds are properly roasted, you won’t have to worry about any of this, but as with anything you are trying for the first time, start with small amounts.

seeds of Kentucky coffeetree

Times and temperatures for roasting vary depending on who you’re getting your information from. I went with 300° F for 3 hours (which ended up being 3 and a half hours because I forgot to take them out in time). One source suggested roasting the seeds for only 2 hours for better flavor, but I decided to err on the side of caution and roast them for longer. Many of the seeds will have popped open during the roasting process. For those that haven’t you will need to use a nutcracker or some other comparable tool to crack the seed coat and remove the insides. Dispose of the seed coats and grind the remaining bits into a fine powder using either a coffee grinder or mortar and pestle. You’ll end up with a fine, chocolate-colored powder which you will use to make your “coffee.”

You can prepare this beverage in the same way you would typically choose to make coffee, but keep in mind that upon adding water, the fine grounds quickly turn to a mud-like substance and will block up the filter you are using. For this reason, I recommend small batches. I found Kentucky coffeetree “coffee” to be very earthy and rich and somewhat similar to strong black coffee. Sierra tried it and immediately exclaimed, “That’s nice!” and then proceeded to give it two thumbs up. Some people like black coffee. I added cream to it and found it much more pleasant to drink. Other people don’t think this beverage tastes like coffee at all and instead call it tea-like, chocolaty, fruity, or “akin to mud,” among other more negative reviews. I think it’s a drink that could grow on me, but considering the effort it takes to make one cup, I don’t see that happening any time soon.

Kentucky coffeetree “coffee grounds”

Have you tried making “coffee” from the seeds of Kentucky coffeetree? Let us know what you think about it in the comment section below.

More Tea Time Posts on Awkward Botany:

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Winter Trees and Shrubs: Kentucky Coffeetree

A few years ago, I was on the hunt for a Kentucky coffeetree. I was aware that a few could be found in some of the parks around Boise, but not being familiar with them, I wasn’t sure where exactly to find one or what I was even looking for. One winter while riding my bike to work, I noticed a tree at the edge of a golf course. No doubt I had passed this tree hundreds (if not thousands) of times. What caught my eye were thick, bean-like pods hanging from the ends of branches. They were unlike any other tree fruits I was familiar with. I stopped and, with a little effort, knocked one of the pods free from the tree. When I split it open, I found three or four large, smooth, black seeds inside. Later, I confirmed that the tree was indeed Kentucky coffeetree. Passing by it during any other time of year, it may have never caught my eye – just another deciduous tree with green leaves that, from a distance at least, looks like so many other deciduous trees. But in winter, with several chunky pods hanging from the tips of its stout branches, it really stood out. This is the joy of looking at trees and shrubs in the winter, where features that may otherwise be obscured, become glaringly obvious against the plainness of a winter backdrop.

fruits of Kentucky coffeetree (Gymnocladus dioicus)

Kentucky coffeetree (Gymnocladus dioicus) is in the bean family (Fabaceae). It occurs in forests across the eastern and central United States and north into southern Ontario, Canada. It is also planted in urban areas both within and outside of its native range. It is a medium to large tree, averaging 60-70 feet (18-21 meters) high and 40-50 feet (12-15 meters) wide. It generally branches out at around 10-15 feet high and forms a narrow, rounded to pyramidal crown. It is a fairly sparsely branched tree compared to other trees its size, which is much easier to observe in the winter after all of its leaves have dropped.

winter twigs of Kentucky coffeetree

The winter twigs of Kentucky coffeetree are thick and stubby with few hairs and can be greenish, orange, brown, or deep wine-red in color. They have small, scattered lenticels that are either white, orange, or orange-brown. Their leaf scars are alternately arranged and are heart- or sheild-shaped and very large with 3 to 5 distinct bundle traces. It’s pretty obvious from the leaf scars that Kentucky coffeetree bears a sizeable leaf. These massive, bipinnately compound leaves are demonstrated in this Plant Sleuth YouTube video. Leaf buds are tiny and found directly above the leaf scar. There are usually two of them, one of which is sterile and can be difficult to see. They are round, hairy, olive-colored, and sunken like fuzzy, little craters, although you’ll need a hand lens to really see the hairs (which I highly recommend). The twigs lack a terminal leaf bud. Their pith is rounded, thick, and either orange, brown, or salmon colored. The young bark of Kentucky coffeetree is pale gray and fairly smooth. As the tree ages, it breaks into shallow ridges that run the length of the tree. At maturity, the bark is shades of grey and scaly with long, defined, narrow ridges.

pith of Kentucky coffeetree twigs

Kentucky coffeetree is dioecious, meaning that there are “male” trees and “female” trees. The tree that I found on the golf course was a “female” tree because it was bearing fruit, which the “males” and certain cultivars won’t have. If there are no seed pods present, you will have to rely on other features to identify the tree; however, when the pods are present, the tree is unmistakable. Its fruits are thick-walled, flat, oval-shaped, smooth, leathery, and orange-brown to black in color. They measure around 5 to 10 inches long and up to 4 inches wide. They are indehiscent and can persist on the tree for more than a year, and even those that fall to the ground can take months or years to break down enough to release the seeds, which have a hard, dark seed coat. Inside the pod, the seeds are embedded in a thick, gooey, yellow-green pulp, which some descriptions call sweet. However, it doesn’t look appetizing enough to try, and considering that the seeds are toxic, I’d be hesitant to consume any part of the fruit without first verifying its safety with a reputable source. That being said, the seeds can be roasted and used to make a coffee substitute and, as long as it’s done correctly, is safe to drink.

mature bark of Kentucky coffeetree

Kentucky coffeetree is one of the last trees to leaf out in the spring and one of the first to drop its leaves in the fall. Flowers appear in mid to late spring. The leaves have a pink to bronze color as they first emerge, and in the fall they turn bright yellow before they drop.

fall foliage of Kentucky coffeetree

More Winter Trees and Shrubs:

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Winter Trees and Shrubs: Tulip Tree

At first glance, a tulip and a tulip tree couldn’t be more different. One is a bulb that puts out fleshy, green leaves in the spring, topped with colorful, cup-shaped flowers, barely reaching a foot or so tall. The other is a massive, deciduous tree with a broad, straight trunk that can grow to nearly 200 feet tall. But if you can get a look at the flowers, seed heads, and even the leaves of this enormous tree, you might see a resemblance – at least in the shape of these features – to one of our most popular spring flowering geophytes.

Tulip tree (Liriodendron tulipifera) is distributed across the eastern United States and has been planted widely outside of its native range. Also commonly known as tulip poplar, yellow poplar, and whitewood, it is a member of the magnolia family and is one of two species in its genus (the other being Liriodendron chinense – a tree found mainly in China). Many (if not most) deciduous trees of North America have small, inconspicuous flowers, but tulip trees – like its close relatives, the magnolias – have relatively large, showy flowers. The trouble is actually getting to see them since, at least on mature trees, they are borne in a canopy that is considerably taller than the average human.

Tulip tree flowers are cup-shaped, yellow-green and orange, with a series of prominent stamens surrounding the carpels which are attached to a long, slender receptacle giving it a cone-shaped appearance. As the flower matures into fruits, the tulip shape of the inflorescence is maintained as the seeds with their wing-like appendages form a tight, cone-like cluster that opens as the seeds reach maturity. The wings aid in dispersal as the seeds fall from the “cone” throughout the winter.

seed head of tulip tree (Liriodendron tulipifera)

The four-lobed leaves of tulip trees also form a vague tulip shape. They are alternately arranged, bright green, and up to five or six inches long and wide, turning yellow in the fall. Two prominent, oval-shaped stipules surround the stem at the base of the petiole of each leaf. These stipules come into play when identifying the leafless twigs of tulip trees during the winter months.

leaf of tulip tree (Liriodendron tulipifera) in late summer

The winter twigs of tulip trees are easily recognizable thanks to their duck bill shaped buds which are made up of two wine-red, violet, or greenish bud scales. The terminal buds are considerably larger and longer than the lateral buds, some of which are on little stalks. The twigs are smooth, olive-brown or red-brown, with just a few, scattered, white lenticels. Leaf scars are rounded with a dozen or so bundle scars that are either scattered or form an irregular ellipse. Pronounced stipule scars encircle the twig at the location of each leaf scar. Twigs can be cut lengthwise to reveal pale white pith that is separated by a series of diaphragms.

winter twig of tulip tree (Liriodendron tulipifera)
top right: the chambered pith of black walnut (Juglans nigra); bottom left: diaphragmed pith of tulip tree (Liriodendron tulipifera)

The bark of tulip trees can be easily confused with that of ash trees. Young bark is smooth and ash-gray to grayish green with pale, vertical cracks. As the tree matures, the cracks develop into furrows with flat-topped ridges. The ridges grow taller and more peaked, and the furrows grow deeper as the tree reaches maturity. In the book Winter Botany, William Trelease compares the mature bark of tulip trees to a series of parallel mountain ranges with deep gullies on either side.

maturing bark of tulip tree (Liriodendron tulipifera)

Perhaps even as tulips are blooming, the buds of tulip trees break to reveal their tulip-shaped, stipule bearing leaves. This makes for an interesting show. In The Book of Forest and Thicket, John Eastman describes it this way: “from terminal buds shaped like duck bills, successions of bills within bills uncurl and unfold, revealing a marvel of leaf packaging.”

More Winter Trees and Shrubs:

The photos of tulip tree were taken at Idaho Botanical Garden in Boise, Idaho.

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All the Plant Shows, part three

In part one and part two of this series, I introduced you to at least 23 plant-themed and plant-related podcasts. But wait, there’s more. As podcasts continue to be such a popular medium for entertainment and education, plant podcasts proliferate. You won’t see me complaining. I’m always happy to check out more botanical content. What follows are mini-reviews of a few more of the plant shows I’ve been listening to lately.

Plants Grow Here – Based in Australia, this is a horticulture and gardening podcast hosted by Daniel Fuller (and the occasional guest host). What separates it from other horticulture-related podcasts is the heavy focus on ecology and conservation. As Daniel says in the introductory episode, “there’s no point in talking about plants at any length without acknowledging that they exist within a wider web.” Daniel interviews plant experts, professionals, and enthusiasts from various parts of the globe, and while much of the focus is on horticulture topics, specifically related to gardening in Australia, there are several episodes that focus solely on the plants themselves and their place in the natural world.

Completely Arbortrary – Relatively new to the scene but an instant classic. Completely Arbortrary is hosted by Casey Clapp, a tree expert, and Alex Crowson, a tree agnostic. In each episode, Casey introduces Alex to a new tree species. After learning all about the tree, they each give it a rating (from zero to ten Golden Cones of Honor!). Sometimes the ratings will surprise you (Alex gave Bradford pear 9.1 Golden Cones of Honor). As the show has gone on, additional segments have been introduced, like Trick or Tree and listener questions. This is easily one of the best plant podcasts around, not just because you’ll learn something about trees (and who doesn’t love trees?), but because you will have a delightful time doing so with a couple of the friendliest and goofiest podcast hosts around.

Naturistic – In the same vein as Completely Arbortrary, Naturistic features host, Nash Turley, telling his co-host friend, Hamilton Boyce, about a natural history topic. At the time of this posting, there are only a handful of episodes available, and not all are plant-focused (most are about animals), but I assume more plant ones are in the works. Either way, each episode is well worth a listen. The topics are well-researched and presented in an amiable and approachable manner. There are also some nicely done videos that accompany some of the episodes.

Flora and Friends – A plant podcast based in Sweden and hosted by Judith, who is also a member of The Plant Book Club. Generally, Judith spends a few episodes with several guests diving deep into a single plant, group of plants, or plant-related topic. So far, there are series of episodes about nasturtiums, Pelargonium, Fritillaria, and forests. Sometimes the episodes are in Swedish, and when that’s the case, Judith refers listeners to a summary in English on the podcast’s website. Each episode is a casual and pleasant chat – or in other words a “botanical tea break” – about the topic at hand, which explains why Judith refers to the podcast as “your botanical cup of tea.”

Field, Lab, Earth – “A podcast all about past and present advances in the fields of agronomy, crop, soil, and environmental sciences.” Produced by a group of three professional societies – American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America – and hosted by Abby Morrison. In each episode, Abby talks with a guest or guests about a research topic, often having to do with agriculture, but sometimes having to do with other aspects of plant and soil science. Listeners get behind the scenes information about how the research was conducted, as well as in depth discussions on the findings. You don’t necessarily need a background in plant and soil science to listen, as many of the basic concepts are well-explained along the way. Also, if you’re a Certified Crop Adviser or Certified Professional Soil Scientist, you can earn Continuing Education Credits by listening to each episode and taking a quiz. Major Bonus!

Backyard Ecology – An urban ecology podcast hosted by Shannon Trimboli. Nature isn’t just some far off place, it’s right outside our doors as well. With a little effort, we can make our yards and other urban spaces more biodiverse and create quality habitat for all sorts of wildlife. Plants are the foundation of our urban habitats, as is the case practically anywhere else, so even when episodes of this podcast are focused on animals, you can be sure that plants are at the heart of the conversation. Join Shannon as she, through conversations with other experts and nature enthusiasts, “ignites our curiosity and natural wonder, explores our yards and communities, and improves our local pollinator and wildlife habitat”

Talking Biotech – This is a long-running podcast hosted by Dr. Kevin Folta that aims to help people better understand the science behind genetic engineering. Folta’s university research supports plant breeding efforts, and many of the episodes of his podcast focus on plant breeding using both traditional methods and genetic engineering. A variety of other aspects and uses of biotechnology are also explored on the podcast. Folta has a passion for science communication and is adamant about debunking misinformation and sharing with the world the promise that new technologies offer us in our efforts to feed the world, improve human health, and address environmental threats. Even if you’re not generally interested in plant breeding, the discussions about the plants and the research is always very interesting and thought-provoking.

War Against Weeds – There is so much more to plants than meets the eye, and what group of plants demonstrates this better than weeds? They are our constant companions, and they are continually outwitting us. Their “craftiness” is one of the reasons I find them so intriguing. Controlling weeds is a constant battle, and few know that battle better than those who work in agriculture. After all, their livelihoods depend on it. War Against Weeds is hosted by three weed scientists whose job it is to help farmers successfully manage weeds. Each episode is a peek into what it takes to do the job. The war may never be won, and the strategies must be diverse – hence the podcast’s tagline, “silver bullets are for werewolves” – and so the conversation will continue. Luckily, we get to listen in.

Arthro-Pod – Just as the name implies, this is an entomology podcast. Insects and plants share an intimate relationship, so I consider this enough of a plant-related podcast to be included here. Plus I really like it. It came to me highly recommended by Idaho Plant Doctor, who is also really into plants and bugs. Hosted by three professional entomologists that all work in extension, Arthro-Pod is a bit like War Against Weeds, but is geared more towards the layperson than the professional. The hosts are humorous and clearly love what they do, which is why, apart from the fascinating discussions about insects, this is such a delight to listen to.

Chances are there will be a part four to this series. If you’re aware of a plant podcast that I haven’t covered yet, please let me know in the comment section below or by sending me a message via the Contact page.

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Winter Trees and Shrubs: Northern Catalpa

The names of plants often contain clues that can either help with identification or that tell something about the plant’s history or use. The name, catalpa, is said to be derived from the Muscogee word, katałpa, meaning “winged head,” presumably referring to the tree’s winged seeds. Or maybe, as one writer speculates, it refers to the large, heart-shaped, floppy leaves that can make it look like the tree is “ready to take flight.” Or perhaps it’s a reference to the fluted, fused petals of the tree’s large, tubular flowers. I suppose it could mean any number of things, but I’m sticking with its seeds, which are packed by the dozens in the tree’s long, slender, bean-like fruits. The seeds are flat, pale brown, and equipped with paper thin, fringed appendages on either side that assist in wind dispersal – wings, in other words.

winged seeds of northern catalpa (Catalpa speciosa)

Catalpa speciosa, or northern catalpa, is a relatively fast growing, short-lived tree native to the Midwest and one of only two species in the genus Catalpa found in the United States. Its distribution prior to the arrival of Europeans appears to have been restricted to a portion of the central Mississippi River valley, extending west into Arkansas, east into Tennessee, and north into Illinois and Indiana. It has since been widely planted outside of its native range, naturalizing in areas across the Midwest and eastern US. Early colonizers planted northern catalpa for use as fence posts, railroad ties, and firewood. Its popularity as an ornamental tree is not what it once was a century ago, but it is still occasionally planted in urban areas as a shade tree. Its messiness – littering the ground below with large leaves, flowers, and seed capsules – and its tendency to spread outside of cultivation into natural areas are reasons why it has fallen out of favor with some people.

The oval to heart-shaped, 8 to 12 inch long leaves with long petioles rotting on the ground below the tree are one sure sign that you’ve encountered a catalpa in the winter time. The leaves are some of the first to fall at the end of the growing season, briefly turning an unmemorable yellow before dropping.

leaf of northern catalpa (Catalpa speciosa) in the winter with soft hairs on the underside still visible

The leaf arrangement on northern catalpa is whorled and sometimes opposite. The twigs are easy to identify due to several unique features. They are stout, round, and grayish brown with prominent lenticels. The leaf scars are large, rounded, and raised up on the twig, looking a bit like little suction cups. They are arranged in whorls of three, with one scar considerably smaller than the other two. A series of bundle traces inside the scar form an ellipse. The leaf buds are tiny compared to the scar and are protected by loose, pointed, brown bud scales. Northern catalpa twigs lack a terminal bud. In the winter, seed capsules or the stalk of an old inflorescence often remain attached to the terminal end of the twig. The pith inside of the twig is thick, white, and solid.

twig of northern catalpa (Catalpa speciosa)

pith inside twig of northern catalpa (Catalpa speciosa)

Another common name for Catalpa speciosa is cigar tree, a name that comes from its up to 18 inch long, cigar-like seed capsules that hang from the otherwise naked tree throughout the winter. The sturdy, cylindrical pod starts out green in the summer and turns dark brown by late fall. Seed pods that haven’t fallen or already split open will dehisce in the spring time, releasing their papery seeds to the wind.

fruits of northern catalpa (Catalpa speciosa) hanging from the tree in the winter

The young bark of northern catalpa is thin and easily damaged. As it matures, it becomes furrowed with either scaly ridges or blocky plates. Mature trees are generally twisted at the base but otherwise grow straight, reaching 30 to 60 feet tall (sometimes taller) with an open-rounded to narrow-oval crown.

maturing bark of northern catalpa (Catalpa speciosa)

Northern catalpa is one of the last trees to leaf out in the spring. In late spring or early summer, 10 inch long clusters of white, tubular flowers are produced at the tips of stems. Before the flowers open, they look a bit like popped popcorn, reminding me of a song from my childhood (which I will reluctantly leave right here). The margins of its trumpet-shaped petals are ruffled and there is yellow, orange, and/or purple spotting or streaking on the inside of the tubes.

flower of northern catalpa (Catalpa speciosa) just before it opens

More Winter Trees and Shrubs on Awkward Botany:

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Winter Trees and Shrubs: Netleaf Hackberry

Boise, Idaho is frequently referred to as the City of Trees despite being located in a semiarid region of the Intermountain West known as the sagebrush steppe where few trees naturally grow. It earns this moniker partly because the name Boise is derived from the river that runs through it (the Boise River), which was named La Rivere Boisse, or The Wooded River, by early French trappers. Although it flows through a largely treeless landscape, The Wooded River was an apt name on account of the wide expanse of cottonwoods and willows that grew along its banks. The fervent efforts of early colonizers to plant trees in large numbers across their new city also helped Boise earn the title, City of Trees. Today, residents continue the legacy of planting trees, ensuring that the city will remain wooded for decades to come.

As is likely the case for most urban areas, the majority of trees being planted in Boise are not native to the region. After all, very few tree species are. However, apart from the trees that flank the Boise River, there is one tree in particular that naturally occurs in the area. Celtis reticulata, commonly known as netleaf hackberry, can be found scattered across the Boise Foothills amongst shrubs, bunchgrasses, and wildflowers, taking advantage of deep pockets of moisture found in rocky outcrops and draws.

The western edge of netleaf hackberry’s range extends to the northwest of Boise into Washington, west into Oregon, and down into California. The majority of its range is found south of Idaho, across the Southwest and into northern Mexico, then east into the prairie regions of Kansas and Oklahoma. Previously placed in the elm family, it is now considered a member of the family Cannabaceae (along with hemp and hops). It’s a relatively small, broad tree (sometimes a shrub) with a semi-rounded crown. It grows slowly, is long-lived, and generally has a gnarled, hardened, twisted look to it. It’s a tough tree that has clearly been through a lot.

The leaves of Celtis reticulata are rough, leathery, and oval to lance shaped with serrate or entire leaf margins. Their undersides have a distinct net-like pattern that gives the tree its common name. A very small insect called a hackberry psyllid lays its eggs inside the leaf buds of netleaf hackberries in the spring. Its larvae develop inside the leaf, feeding on the sugars produced during photosynthesis, and causing nipple galls to form in the leaves. It’s not uncommon to see a netleaf hackberry with warty-looking galls on just about every leaf. Luckily, the tree doesn’t seem to be bothered by this.

fallen leaves of netleaf hackberry (Celtis reticulata) with nipple galls

The fruit of netleaf hackberry is a pea-sized drupe that hangs at the end of a pedicel that is 1/4 to 1/2 inch long. Its skin is red-orange to purple-brown, and its flesh is thin with a large seed in the center. The fruits, along with a few random leaves, persist on the tree throughout the winter and provide food for dozens of species of birds and a variety of mammals.

persistent fruit of netleaf hackberry (Celtis reticulata)

Celtis reticulata is alternately branched. Its twigs are slender, zig-zagging, and often curved back towards the trunk. They are reddish-brown with several pale lenticels and have sparse, fine, short hairs that are hard to see without a hand lens. The leaf scars are small, half-round, and raised up from the twig. They have three bundle scars that form a triangle. The buds are triangle-shaped with fuzzy bud scales that are slightly lighter in color than the twig. The twigs are topped with a subterminal bud, and the pith (the inner portion of the twig) is either chambered or diaphragmed and difficult to see clearly without a hand lens. 

twigs of netleaf hackberry (Celtis reticulata)

The young bark of netleaf hackberry is generally smooth and grey, developing shallow, orange-tinged furrows as it gets older. Mature bark is warty like its cousin, Celtis occidentals, and develops thick, grey, corky ridges. Due to its slow growth, the bark can be retained long enough that it becomes habitat for extensive lichen colonies.

bark of young netleaf hackberry (Celtis reticulata)

bark of mature netleaf hackberry (Celtis reticulata)

Netleaf hackberry is one of the last trees to leaf out in the spring, presumably preserving as much moisture as possible as it prepares to enter another scorching hot, bone-dry summer typical of the western states. Its flowers open around the same time and are miniscule and without petals. Their oversized mustache-shaped, fuzzy, white stigmas provide some entertainment for those of us who take the time to lean in for a closer look.

spring flowers of netleaf hackberry (Celtis reticulata)

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Photos of netleaf hackberry taken at Idaho Botanical Garden in Boise, Idaho.

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Winter Trees and Shrubs: Eastern Redbud

Botanizing doesn’t have to end when the leaves fall off the trees and the ground goes frozen. Plants may stop actively growing during this time, but they are still there. Some die back to the soil level and spend the entire winter underground, leaving behind brown, brittle shells of their former selves. Others, particularly those with woody stems, maintain their form (although many of them leafless) as they bide their time while daylength dips and rises again, bringing with it the promise of warmer weather. Plants that leave us with something to look at during the winter can still be identified. Without foliage or flowers to offer us clues, we rely instead on branches, bark, and buds to identify woody species. In some cases, such features may even be more helpful in determining a certain species than their flowers and foliage ever were. Either way, it’s a fun challenge and one worth accepting if you’re willing to brave the cold, hand lens and field guides in tow.

In this series of posts I’ll be looking closely at woody plants in winter, examining the twigs, buds, bark, and any other features I come across that can help us identify them. Species by species, I will learn the ropes of winter plant identification and then pass my findings along to you. We’ll begin with Cercis canadensis, an understory tree commonly known as eastern redbud.

Eastern redbud is distributed across central and eastern North America, south of southern Michigan and into central Mexico. It is also commonly grown as an ornamental tree outside of its native range, and a number of cultivars have been developed for this purpose. Mature trees reach up to 30 feet and have short trunks with wide, rounded crowns. Its leaves are entire, round or heart-shaped, and turn golden-yellow in the fall. Gathered below the tree in winter, the leaves maintain their shape and are a light orange-brown color.

fallen leaf of eastern redbud (Cercis canadensis)

Eastern redbud is alternately branched with slender, zig-zagging twigs that are dark reddish-brown scattered with several tiny, light-colored lenticels. Older sections of branches are more grey in color. Leaf scars (the marks left on twigs after leaves fall) are a rounded triangle shape and slightly raised with thin ridges along each side. The top edge of the leaf scar is fringed, which I found impossible to see without magnification. Leaf buds are egg-shaped and 2-3 mm in length with wine-red bud scales that are glabrous (smooth) with slightly white, ciliate margins. Descriptions say there are actually two buds – one stalked and one sessile. If the second bud is there, it’s miniscule and obscured by the leaf scar. I haven’t actually been able to see one. Twigs lack a terminal bud or have a tiny subterminal bud that points off to one side. The pith of the twigs is rounded and pale pink. Use sharp pruners or a razor blade to cut the twig in half lengthwise to see it.

twig and buds of eastern redbud (Cercis canadensis)

Bark is helpful in identifying woody plants any time of year, but is especially worth looking at during the winter when branches have gone bare. The bark of young eastern redbud is grey with orange, furrowed streaks running lengthwise along the trunk. In mature trees, the bark is gray, scaly, and peels to reveal reddish-brown below.

bark of young eastern redbud (Cercis canadensis)

bark of mature eastern redbud (Cercis canadensis)

Eastern redbud is in the bean family (Fabaceae) and its flowers and fruits are characteristic of plants in this family. Fruits can persist on the tree throughout the winter and are another way to identify the tree during the off-season. Seed pods are flat, dark red- or orange-brown, and up to 2.5 inches long with four to ten seeds inside. The seeds are flat, round, about 5 millimeters long, and ranging in color from orange-brown to black.

persistent fruits of eastern redbud (Cercis canadensis)

seeds of eastern redbud (Cercis canadensis)

Eastern redbud flowers in early spring before it has leafed out. Clusters of bright pink flowers form on old branches rather than new stems and twigs. Sometimes flowers even burst right out of the main trunk. This unique trait is called cauliflory.

cauliflory on eastern redbud (Cercis canadensis)

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Photos of eastern redbud taken at Idaho Botanical Garden in Boise, Idaho.

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A Few More Snags Near Ketchum

Nearly a year has passed since Sierra and I took a trip to Ketchum, Idaho and I reported on some of the snags we encountered there. After months without a break, we finally had the chance to get away for a few days, and since we were desperate for some time off and a change of scenery, we couldn’t turn it down. Plus, we were heading back to Ketchum, so I knew I’d get to check out a few more snags. I was stoked.

I’m obsessed with trees, and my preference is for live ones (generally speaking), but dead trees are certainly gaining in popularity. After all, a dead tree isn’t truly dead. As its corpse slowly rots, it continues to harbor and support life inside and out in a substantial way. Forests need dead trees just as much as they need live trees. Plus, ecology aside, dead trees are no less photogenic than any other tree.

Death isn’t all bad. New life springs from decay. Given our current state of affairs, we need this reminder, and snags offer it in spades. As Sierra and I pulled up to the Apollo Creek trailhead, we looked out onto a section of forest that had clearly been ravaged by fire in the not too distant past. Acres of standing and fallen burned out trees bore witness to this fact. Yet among the dead, life flourished, as dozens of songbirds actively foraged on and around the charred trees. They were there for the insects that were feeding on the dead wood, fueling themselves for fall migration. In the spring, when the birds return, some of them may even nest in the cavities of the dead trees. They will feed again on the insects and raise up a new generation of songbirds that will do the same. In and among snags there are myriad examples just like this, showing us the countless ways in which death supports new life.

What follows is a small sampling of the snags we encountered this time around on our trip to Ketchum.

post-fire snag among many other snags

a series of cavities in a post-fire snag

snag surrounded by live trees

three new snags

fallen snag

broken snag

new tree emerging from a nurse stump

not a snag, but one of many lupines we saw flowering along Apollo Creek Trail

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Revisiting the Moon Tree

I first learned about Moon Trees in the fall of 2015. One of the trees – a loblolly pine – had been planted at an elementary school just down the street from where I was living at the time. It wasn’t a new thing – it was planted back in 1977, during the period when most other Moon Trees where being planted around the country and the world – but because it wasn’t doing too well, it was in the news. Members of the community, concerned about its long-term survival, were pitching in to help keep it alive. Once I was made aware of it, I also became concerned and decided to go check on it. I even wrote a post about it, which you can read here.

Now that nearly 5 years have passed, I figured I should go check on it again. I hadn’t heard any more news about it, so I assumed it was still hanging in there, but who knows? Maybe not. Since I was going to be on that side of town for Father’s Day, I made plans to stop by. My dad hadn’t seen the tree yet, so he decided to join me.

As we approached Lowell Elementary on our bikes, I was half-expecting the tree to be gone. It was in pretty sad shape when the community stepped in to help it. Braced for this possibility, I anxiously peered down the street as we biked closer. When the tree came into view, I felt relief and announced, “There it is!”

All this time later, it still looks a little rough. The majority of its bark remains largely obscured by crusty, dried up sap, and its canopy isn’t as full as it likely would be if it was a picture of health. But it’s alive and, surprisingly enough, still growing taller, reaching for the moon.

Any loblolly pine would feel out of place in Idaho – it’s a species whose distribution spans the southwest region of the United States, which is starkly different from the northwest – however, this individual in particular is an anomaly. The seed it sprouted from took a journey into space, circled the moon a number of times and then, as a sapling, was planted in Idaho (of all places). Now, over 40 years later, it stands as a symbol of resilience. Something we could all use right now, I’m sure.

This sign was installed shortly after my original Moon Tree post.

Boise, Idaho’s Moon Tree in June 2020

My dad by the Moon Tree in Boise, Idaho

Me by the Moon Tree in Boise, Idaho

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Was a Moon Tree planted near you? Is it still around? Tell us about it in the comment section below.