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:

2022: Year in Review

It’s time to look back on 2022. But before we do that, I have to acknowledge that January 2023 marks Awkward Botany’s 10 year anniversary. This time ten years ago, I was drafting the introductory post to this blog. Obviously, a lot has happened since then, yet it still seems like yesterday somehow. And while I may not be posting with the frequency that I once was, I’m still at it, and I don’t plan on stopping any time soon. There is so much we have yet to cover. I feel like we’ve barely scratched the surface of what the world of plants has to offer. If you’d like to look back on what I’ve written about over the years, these Year in Review posts are a good place to start, which I’ve been posting each year since Awkward Botany turned one. Looking forward, expect more of the same, which if you’re into plants as much as me, should be enough to keep your attention. If you’re not into plants, I’m not sure why you’re here, but since you are, I hope that what I share might change your mind. Either way, here’s to another 10 years!

Awkward Botany Turns 10!

Perhaps the most eventful thing that happened in 2022, as far as the blog goes, was my appearance on Outdoor Idaho where I got to sing the praises of weeds and the role they play as members of our wild flora. You can expect the weeds talk to continue, especially since Western Society of Weed Science’s Annual Meeting is coming to Boise later this winter. Perhaps I’ll see you there! Oh, and speaking of annual meetings, Botany is coming to Boise this summer, so please feel free to say hello if you’re coming to town.

As per usual, I have a head full of ideas and plans for the upcoming year, and I am hopeful that it will be one of the best yet. But I will spare you from having to trudge through that whirlwind, and instead I’ll just say thank you for being here. Thanks for your comments, shares, follows, and the other ways you show your support. If you’d like to continue doing so, by all means, please do. If you’re new here and you’d like to start, all relevant links are in the link tree below. Happy 2023 everyone!

Awkward Botany Linktree

And now…

A Selection of Posts from 2022

Winter Trees and Shrubs

Book Reviews

Weeds of Boise

Eating Weeds

Randomly Selected Botanical Terms

Guest Posts

Book Review: A Gardener’s Guide to Botany

Avid gardeners spend a lot of time getting up close and personal with their plants. Whether they have a background in botany or not, they are bound to notice things about plants that others won’t. Questions are sure to arise about what their plants are up to, how they manage to do the things they do, or what might be done to help make their lives better. In the age of information, answers can be found at the touch of a button and from a wide variety of sources, some more trustworthy than others. The latest resource for gardeners with a question is A Gardener’s Guide to Botany. Written by plant expert and seasoned science communicator, Scott Zona, this is a source of information that’s not only trusted and highly credible, but also approachable for readers at any level and an absolute joy to read.

A Gardener’s Guide to Botany by Scott Zona, Ph.D.

You may know Zona as the go-to guy when it comes to questions about palms or tropical plants, but his knowledge of the plant kingdom extends far beyond these diverse groups. Zona has spent the majority of his life studying plants in all their forms across a wide variety of landscapes and has been sharing his knowledge through various institutions and societies that he’s been a part of along the way. His book is like a summary or overview of all the things he’s learned throughout this journey. It’s also just the beginning, a jumping off point and invitation to learn even more about the endlessly fascinating world of botany.

In the first chapter, Zona helps us understand just what makes a plant a plant – what separates plants from all other walks of life, and what plants have in common with other living things. Plants were one of the first forms of life that came about in the early years of life on our planet. Their evolution helped set the stage for so many other lifeforms to come. Due to the fact that they are generally fixed to one spot for the duration of their lives, they have had to adapt to deal with a wide variety of threats and stressors without the benefit of being able to run away or head for higher ground. As climates around them have changed and landscapes have shifted, so have they. All the while, plants have continued to be primary producers and ecosystem engineers, benefiting the lives of so many other living things, including humans, right up until this very day. Their existence is critical to the continuation of life on earth. Many of the ways that plants have been able to be so successful for so many millions of years are described in Zona’s book.

The second chapter of A Gardener’s Guide to Botany is a lesson in plant anatomy. Zona provides an overview of the inner and outer workings of roots, shoots, leaves, flowers, and fruits. Understanding basic plant anatomy can be important for maintaining a successful garden; it’s also just incredibly interesting in its own right. Plants are simple constructions, yet show up in such diverse forms. By modifying their limited parts, they are able to produce a wide variety of interesting features unique to each species. A branch becomes a thorn, a leaf becomes a spine, a root becomes a fleshy storage organ, an inflorescence becomes a tendril. This is just the beginning of the many surprises plants have up their sleeves.

The tendrils of grape vines (Vitis spp.) are modified, sterile inflorescences.

The next three chapters are all about what plants need to survive, namely water, light, and nutrients. Gardeners know that if any of these three things are out of whack, their plants are sure to suffer. Luckily, plants have some experience adapting a number of ways to get the things they need. Roots can search the soil for water and pockets of nutrients. Shoots move in search of light and can produce leaves that match the intensity or amount of sunlight (smaller and thicker in full sun, broader and thinner in the shade). Relationships can be made with microbes that live in the soil in order to gain access to resources, and even to help plants defend themselves (which is the subject of chapter six). Sometimes light is too intense for plants, and plants have developed features to deal with this such as waxes on their leaves, hairy or fuzzy leaf surfaces, or additional plant pigments that can act as sunscreen. Some of these features also help the plant retain water when temperatures are high. Other plant species have adaptations to live in water-abundant environments, such as drip tips on their leaves to help them shed water or special tissues in their stems and roots that help facilitate gas exchange.

Plants need light to carry out photosynthesis, so the more light the better. But not always. The newly emerging leaves of some species are red, orange, and/or yellow in color which helps protect the developing tissues from the intensity of the sun until the tissues have time to mature, at which point they turn their standard green color. In the fall, the leaves of deciduous plants experience a similar color change but in reverse. This change serves a similar function, protecting leaves from sun damage as they reabsorb nutrients back into the plant.

Lovage (Levisticum officinale) emerges in the spring, its leaves first taking on hues of purple and yellow which help protect the developing tissues from harsh, direct sunlight.

The chapter about defense is sure to be a popular one. Who doesn’t enjoy learning about the many ways these stationary organisms have developed to defend themselves against hordes of invaders out to destroy them? From fortifications like thorns, spines, and sticky hairs to any number of toxic substances produced within their tissues, many of which humans have learned to use for our own benefit. Some plants even recruit other species to help them out, like ants, mites, and various microbes. Of course, for all the defenses they put up, there are at least a few herbivorous creatures that manage to find a work around. And so the war continues.

In the following chapter, Zona covers another popular topic, plant sex. Pollinators and pollination have gained a lot of interest over the past decade or so, particularly among gardeners. Turning our gardens into habitats for bees and other insect pollinators is one way we can help conserve these important organisms. Understanding more about the specifics of pollination and plant reproduction will only help us improve these efforts. Learning about the many ways by which plants reproduce asexually also helps us out when we are trying to make more plants. Successful plant propagation and plant breeding rely on a good understanding of the concepts that Zona covers in chapter seven.

The bright yellow spots on the petals of snapdragons (Antirrhinum sp.) mimic pollen-loaded anthers and help draw in pollinators.

The final chapter is all about dispersal – how plants get around – and is one that I will be returning to repeatedly for some time. Plant dispersal is one of my favorite topics, and Zona does not disappoint. All the basic means of getting around are covered, and with them come dozens of stories that demand a curious mind look further into, like palm fruit dispersal by electric eels or the aardvarks that disperse the seeds of underground cucumbers. This a chapter that could have gone on for the whole book.

One of my favorite things about this book is that for the majority of the topics that Zona discusses, plant examples are given so that you can see for yourself, and many of those plants can be easily found either as a common garden plant or indoor houseplant. This means that you don’t have to travel the world to familiarize yourself with these concepts, instead you can see them in action right outside your door. Most of us, whether we have a garden or not, have easy access to plants, even if it’s just the weeds growing in the sidewalk cracks. This makes getting to know the Plant Kingdom a possibility for nearly anyone. As Zona writes, “a stroll in the garden or a hike through the woods is all it takes to begin a journey into a leafy, green world.” Let his book be “your passport, your interpreter, your currency converter, and your host on a learning adventure into the world of plants.”

More Book Reviews:

The Life Cycle of a Sunflower Stem Weevil

Last summer I came across a downy woodpecker hammering away at the stalk of a sunflower. I wondered what it was going after, and so I split open a stalk lengthwise to find the center of the stem hollowed out and several small larvae squirming through the debris left behind. A quick internet search later and I was learning about sunflower stem weevils, specifically Cylindrocopturus adspersus, which seems to be the species getting the most attention online and the stem-dwelling weevil that commercial sunflower growers seem most concerned about.

However, the range of sunflower stem weevil doesn’t appear to extend into Idaho, and so this is not likely to be the larvae I was seeing. There are other weevil species whose larvae can be found inside the stems of sunflowers (The sunflower I was observing was Helianthus annuus. I wasn’t specific about naming a particular species because it is my understanding that these weevils can be found on a variety of different Helianthus species., such as the cocklebur weevil (which is found in Idaho), but since larvae can be difficult to identify, I’ll wait to confirm the identity until I hear from an expert, find an adult weevil, and/or raise the larvae in captivity and see what it turns into. If and when that happens, I’ll be sure to update you. Until then, I present to you the life cycle of a sunflower stem weevil, which is still quite interesting, even if it’s not the species I found inside my sunflower stalks. And to be clear, the sunflower I observed was Helianthus annuus; however, the weevils I refer to in this post can be found on a number of different Helianthus species and related genera.

Sunflower stem weevils are in the family Curculionidae, which is the snout and bark beetle family. There are tens of thousands of species of weevils, a handful of which interact with sunflowers (plants in the genus Helianthus). Some weevil species eat the seeds, others eat the leaves, some are root feeders, while others are stem feeders. Depending on the life stage of a particular weevil species, it may consume multiple parts of a sunflower. Another interesting weevil is the sunflower headclipping weevil, which you can read about at The Prairie Ecologist.

Adult sunflower stem weevils are about 3/16 inch (4-5 mm) long and somewhat egg or oval shaped. They are grayish-brown with white spots. Their eyes, antennae, and snout are black, and their snout is short, curved, and held beneath the head. As adults, they can be found on sunflowers and sunflower relatives eating the leaves. However, they are not easily found. Their size, for one, makes them difficult to see, and they also move to the opposite sides of leaves and stems when disturbed, sometimes dropping to the ground as a threat approaches. You can see images of them on BugGuide.

unidentified larva in a sunflower stem

The larvae of sunflower stem weevils are about a quarter of a inch long and creamy white with a small, brown head capsule. They feed in the vascular tissue of sunflower stalks during the summer. In the fall, they migrate to the base of the stalks and create chambers in the woody tissue of the stalks and root crowns for overwintering.

Sunflower stem weevils have a single generation per year. After overwintering as larvae in the base of last year’s sunflowers, they pupate and emerge as adults in late spring or early summer. They find young sunflower plants and begin feeding on the leaves. After about 2-4 weeks, the weevils mate and lay eggs just beneath the epidermis of sunflower stems, usually in the stalk just below the cotyledon leaves. The eggs hatch a short time later and begin feeding in the stem until it’s time to overwinter.

the life cycle of a sunflower stem weevil

The damage caused by sunflower stem weevils is generally only a problem on sunflower farms, and only when weevils are found in high enough numbers to cause significant yield losses. Damage to leaves by the adults isn’t usually a concern. On the other hand, as the larvae tunnel through the stem, they can cause the plant to lodge (i.e. fall over prematurely), which is a problem particularly when the plants are machine harvested. Sunflower stem weevils can also introduce and help spread a fungus that causes black stem rot.

Read More About Sunflower Stem Weevil and Other Insect Pests of Sunflowers:

Eating Weeds: Cleavers Coffee

One of the world’s most beloved beverages comes from a species of plant found in the fourth largest family of flowering plants. Rubiaceae, also known as the coffee or bedstraw family, consists of around 13,500 species, placing it behind just Asteraceae, Orchidaceae, and Fabaceae for the most number of species. Coffea arabica, and other species in the genus Coffea, are grown for their fruits which are used to make coffee. This makes Rubiaceae one of the most economically important plant families. A family this size is bound to be home to a weed or two, and in fact, one of the most widespread and obnoxious weeds is also a member of Rubiaceae.

Galium aparine, known commonly by a slew of names including cleavers, occurs naturally across large portions of Europe, Asia, North Africa, and possibly even parts of North America. It has been introduced as a weed in many locations across North America, South America, Australia, New Zealand, Japan, and parts of Africa. It is of particular concern in agricultural settings where its lengthy, sprawling branches and sticky leaves get tangled up in harvesting equipment, while its tiny, prickly fruits get mixed in with seeds of similar size like canola.

Galium aparine

Sticky willy, as it is also known, is an annual plant that, in some cases, can have two generations per year – one in the spring (having germinated the previous fall) and one in the summer. Its stems are square, though not as sharply square as plants in the mint family, and can grow to around six feet long. They are weak, brittle, and don’t stand upright on their own; instead they are found scrambling across the ground or, when given the opportunity, climbing up the lengths of other plants in order to reach the sunlight. Leaves occur in whorls of six to eight and are simple and slender with entire margins. Flowers are produced at leaf axils along the lengths of the branches and are tiny, four-petaled, star-shaped, and greenish white. Fruits are borne in pairs and are round, single-seeded, indehiscent nutlets. The stems, leaves, and fruits are covered in stiff, hooked hairs or trichomes, earning it other names like catchweed bedstraw, grip grass, stickyweed, and velcro plant.

flowers and immature fruit on Galium aparine

Galium aparine is a climbing plant, but unlike other climbing plants, it doesn’t twine up things or produce structures like tendrils to hold itself up. Instead, its ability to climb is made possible by its abundant bristly hairs. A paper published in Proceedings of the Royal Society B (2011) investigates the way G. aparine climbs up other plants using the hairs on its leaves. A close inspection of the leaves reveals that the trichomes on the top of the leaf (the adaxial leaf surface) differ significantly from those found on the bottom of the leaf (the abaxial leaf surface). Adaxial trichomes curve towards the tip of the leaf, are hardened mainly at the tip, and are evenly distributed across the leaf surface. Abaxial trichomes curve towards the leaf base, are hardened throughout, and are found only on the midrib and leaf margins.

Having different types of hairs on their upper and lower leaf surfaces gives cleavers an advantage when it comes to climbing up neighboring plants. The authors of the paper describe the technique as a “ratchet mechanism.” When the upper surface of their leaf makes contact with the lower surface of another plant’s leaf, the flexible, outwardly hooked trichomes inhibit it from slipping further below the leaf and allow it to easily slide out from underneath it. When the lower surface of their leaf makes contact with the upper surface of another plant’s leaf, the stiff, inwardly hooked trichomes keep it attached to the leaf even if the other leaf starts to slip away and allows it to advance further across the leaf for better attachment and coverage. Using this ratchet mechanism, cleavers climb up the leaves of other plants, keeping their leaves above the other plant’s leaves, which gives them better access to sunlight. The basal stems of cleavers are highly flexible, which keeps them from breaking as the plant sways in the wind, tightly attached to their “host” plant.

fruits of Galium aparine

The hooked trichomes on the tiny fruits of cleavers readily attach to the fur and clothing of passing animals. The nutlets easily break free from the plants and can be transported long distances. They can also be harvested and made into a lightly caffeinated tea. Harvesting the fruit takes time and patience. I spent at least 20 minutes trying to harvest enough fruits for one small cup of cleavers coffee. The fruits don’t ripen evenly, and while I tried to pick mostly ripe fruits, I ended up with a selection of fruits in various stages of ripeness.

To make cleavers coffee, first toast the seeds for a few minutes in a pan heated to medium high, stirring them frequently. Next, grind them with a mortar and pestle and place the grinds in a strainer. Proceed as you would if you were making tea from loose leaf tea.

The toasted fruits and resulting tea should smell similar to coffee. The smell must not be strong, because my poor sense of smell didn’t really pick up on it. The taste is coffee-like, but I thought it was more similar to black tea. Sierra tried it and called it “a tea version of coffee.” If the fruits were easier to collect, I could see myself making this more often, but who has the time?

The leaves and stems of Galium aparine are also edible, and the plant is said to be a particular favorite of geese and chickens, bringing about yet another common name, goosegrass. In the book Weeds, Gareth Richards discusses the plant’s edibility: “It’s edible for humans but not that pleasant to eat; most culinary and medicinal uses center around infusing the plant in liquids.” Cooking with the leaves or turning them into some sort of spring tonic is something I’ll consider for a future post about eating cleavers.

More Eating Weeds Posts on Awkward Botany

Apriums and Plumcots and Pluots, Oh My!

I was once a teenage paper carrier in small town Idaho. One of my stops was an apartment complex, and for much of the year, this was an uneventful stop. But for a few weeks in the summer, the purple-leaved plum trees out front had ripe fruit on them, and each time I was there, I would stop and take a few. In general, I don’t get that excited about fruit, but I enjoyed eating these plums. This variety of plum is typically planted for its looks rather than its fruit, and it may even be the tree that recently received a pitifully low score on an episode of Completely Arbortrary. Ornamental plum or not – and low cone score or not – I thought the fruit was good.

Many of the things we eat are a result of crosses between two related species, and plums are a great example of this. Species are species because they are reproductively isolated. A species does not typically mate with a member of another species and create viable offspring, except this happens all the time both naturally and artificially. In many cases, the offspring isn’t actually viable, but there is offspring nonetheless, and in the case of plants, that offspring can then reproduce asexually – by leaf, stem, or root cuttings or by some other means – and the resulting hybrid can exist indefinitely. One species mating with another species (specifically two species that are members of the same genus) is called interspecific hybridization, and there is a good chance that you’ve eaten something recently that is a result of this.

One of the most widely grown species of plum, Prunus domestica (commonly known as European plum), is a result of interspecific hybridization that occurred many centuries ago. A paper published in Horticulture Research (2019) confirmed that P. domestica originated as a cross between Prunus cerasifera and Prunus spinosa, the latter of which may have also been a result of interspecific hybridization. There are over 400 species in the genus Prunus that are distributed across temperate regions in the northern hemisphere. Within this genus is the subgenus Prunus (or Prunophora), a group that includes dozens of familiar species such as the plums, apricots, peaches, and almonds. Due to their close relationship, both natural and artificial hybridization among members of this subgenus is common, which explains the origin of Prunus domestica, as well as the majority of the plums we grow today.

Current commercial production of plums in North America is largely thanks to work done by Luther Burbank in the late 19th to early 20th centuries. Burbank was obsessed with plant breeding and released hundreds of new varieties of all kinds of different plants during his decades long career. He seemed particularly interested in plums, developing 113 different cultivars, which account for more than half of all his fruit releases. Probably his most well known plum variety is ‘Santa Rosa,’ which thanks to modern day genetics has been determined to be a cross between at least four different species of plum.

apriums

Early colonizers to the American continent were mainly growing varieties of the European plum they had brought over from Europe. North America is also home to several species of plums, which are used by indigenous populations. Shortly before Burbank began working with plums on his farm in California in 1881, Asian plum species were imported to the U.S., and breeders began using them in crosses with both European and North American plum species. Burbank became particularly engulfed in these efforts. In an article published in HortScience (2015), David Karp writes, “In the history of horticulture it is rare to find an individual who almost single-handedly created a new commercial industry based on a novel fruit type as Luther Burbank did for Asian-type plums in the United States.” Most Asian-type plums sold in stores today are hybrids of several different plum species due to the numerous complex crosses that Burbank made.

Burbank is also said to be the first to cross plums and apricots, creating the first of many cultivars of the plumcot. Plum and apricot crosses didn’t really catch on for a few more decades, and when they did, it was thanks to the work of Floyd Zaiger of Zaiger Genetics who developed and released numerous varieties. Apriums and Pluots are Zaiger Genetics trademarks, along with a few other unlikely crosses with plums and their related counterparts.

plumcots

A plumcot is the simplest cross. It is said to be 50% Asian plum (Prunus salicina) and 50% apricot (Prunus armeniaca). However, due to all the breeding of Asian plums carried out by Burbank and others, the Asian plum involved in the cross is typically a hybrid with other plum species, as discussed in a recent paper published in Plants (2022). An aprium is the result of a cross between a plumcot and an apricot, making it 75% apricot and 25% plum, while a pluot is a cross between a plumcot and a plum, making it 75% plum and 25% apricot. There is typically much more that goes into making these crosses, but that’s the general idea. If you’re lucky, you can find all three of these intraspecific crosses in a produce section near you, but it may not be clear what cultivar you’re purchasing. Myriad cultivars have been released of each of these hybrids – each one varying in color, size, flavor, disease resistance, etc. – and unfortunately most grocery stores don’t include cultivar names on their products, so it’s difficult to know what you’re getting.

At Awkward Botany Headquarters, there is a plum tree growing in our front yard. We didn’t plant it, so at this point I have no idea what species or cultivar it is. The plums are delicious though, and the leaves aren’t purple like the plums I used to eat on my paper route. Considering all of the intraspecific crossing that has gone on with plums, it’s quite likely that it is a combination of different species, which isn’t going to make it easy to figure out. But I’ll do my best.


Check out the linktree for various ways to follow and support Awkward Botany.

Randomly Selected Botanical Terms: Glochids

The spines of a cactus are an obvious threat. They are generally sharp, smooth, and stiff; as soon as you are stabbed by one, it is immediately clear that you’ve gotten too close. Sitting at the base of the spines – or in place of spines – on many species of cacti is a less obvious, but significantly more heinous threat. Unless you’re looking closely, this hazard is practically invisible, and the pain and irritation that can come as a result of close contact has the potential to last significantly longer than the sharp poke of a spine. This nefarious plant part is called a glochid, and if you’ve ever made contact with one (or more likely several dozen of them), it’s not something you will soon forget.

Opuntia polyacantha x utahensis

The spine of a cactus is actually a leaf. The area from which a spine emerges from the fleshy, photosynthetic stem of a cactus is called an areole, which is equivalent to a node or bud on a more typical stem or branch from which leaves emerge. In place of typical looking leaves, a cactus produces spines and glochids. Like spines, glochids are also modified leaves, although they appear more like soft, little tufts of hair. However, this unassuming little tuft is not to be trifled with.

Close inspection of a glochid (with the help of a microscope) reveals why you don’t want them anywhere near your skin. While the surface of a cactus spine is often smooth and free of barbs, glochids are covered in backwards-facing barbs. The miniscule size of glochids combined with their pliable nature and retrose barbs, make it easy for them to work their way into your skin and stay there. Unlike spines, glochids easily detach from a cactus stem. Barely brushing up against a glochid-bearing cactus can result in getting stuck with several of them.

Opuntia basilaris var. heilii

Because glochids can be so fine and difficult to see, you may not even be aware they are there. You probably won’t even feel them at first. Removing them is a challenge thanks to their barbs, and since you may not be able to remove them all, the glochids that remain in your skin can continue to cause irritation for days, weeks, or even months after contact. For this reason, cactuses are generally best seen and not touched, or at the very least, handled with extreme care.

Apart from being a good form of defense, the glochids of some cactus species can serve an additional function. Most cactus species occur in arid or semi-arid climates, where access to water can be quite limited. In order to increase their chances of getting the water they need, some desert plants are able to collect water from the air. A few species of cactus do this, and glochids are a critical component in making this happen.

Cylindropuntia whipplei

A study published in the Journal of King Saud University – Science (2020) examined the dew harvesting ability of Opuntia stricta, commonly known as erect prickly pear. As described above, the spines of O. stricta are smooth, while the glochids are covered in retrose barbs. Both structures are waterproof due to hardened cell walls and cuticles. However, due in part to the conical shapes of both the glochids and their barbs, water droplets from the air are able to collect on the tips of the glochids. From there, the researchers observed the droplets in their travel towards the base of the glochids. As they moved downward, small droplets combined to form larger droplets.

At the base of the glochids are a series of trichomes, which are small hair-like outgrowths of the epidermis. The trichomes do not repel water, but rather are able to absorb the droplets as they reach the base of the glochids. For a plant species that receives very little water from the soil, being able to harvest dew from the air is critical for its survival, and this is thanks in part to those otherwise obnoxious glochids.

See Also: Prickles

Weeds of Boise: Hellstrip on Jefferson Street

Growing plants in urban areas comes with a variety of challenges. Soil conditions aren’t always ideal; shade thrown by buildings and other structures can be difficult to work around; paved surfaces lead to compaction and, among other things, can increase temperatures in the immediate area; and in locations where water is limited, keeping plants hydrated is a constant concern. One location that tends to be especially difficult for gardeners is the hellstrip – the section of ground between a roadway and a sidewalk. Much can be said about gardening in hellstrips, so much that there is even a book about it called Hellstrip Gardening by Evelyn Hadden, which I spent several posts reviewing a few years back.

The difficulty of maintaining a hellstrip (and perhaps questions about who is responsible for maintaining it in the first place) can result in it being a piece of property frequently subject to neglect. In urban areas, neglected land is the perfect place for weeds to take up residence. The conditions in a hellstrip being what they are – hot, dry, frequently trampled, and often polluted – also gives weeds a chance to show what they can do. It’s a wonder that any plant can survive in such conditions, but the wild flora of our cities consists of some pretty tough plants, and a hellstrip is an excellent location to familiarize yourself with some of these plants.

On a walk with Kōura, I came across a weedy hellstrip on Jefferson Street in downtown Boise. Many of the classic hellstrip challenges are present there – it’s surrounded by paved surfaces, there is lots of foot traffic in the area, parking is permitted on the roadside, urban infrastructure (street signs, parking meters, stoplights) is present within the strip. It’s clear that at one point the area was being maintained as irrigation is installed and there are remnants of turfgrass. Three honey locusts were also planted in the strip, one of which has clearly died. Now that maintenance seems to have ceased, weeds have become the dominant flora in this hellstrip. What follows are a few photos and a list of the weeds I’ve identified so far. Like all posts in the Weeds of Boise series, this list may be updated as I continue to check back in on this location.

shepherd’s purse (Capsella bursa-pastoris) and prickly lettuce (Lactuca serriola)
dandelion (Taraxacum officinale)
salsify (Tragopogon dubius)
seed head of salsify
knotweed (Poylgonum sp.)
prickly lettuce (Lactuca serriola)
mallow (Malva neglecta)
orchard grass (Dactylis glomerata)
  • Bromus tectorum (cheatgrass)
  • Capsella bursa-pastoris (shepherd’s purse)
  • Dactylis glomerata (orchard grass)
  • Epilobium brachycarpum (tall willowherb)
  • Lactuca serriola (prickly lettuce)
  • Malva neglecta (dwarf mallow)
  • Polygonum sp. (knotweed)
  • Salsola sp. (Russian thistle)
  • Taraxacum officinale (dandelion)
  • Tragopogon dubius (salsify)
  • Trifolium repens (white clover)
  • Vulpia myuros (rattail fescue)

Are there unkept hellstrips in your neighborhood? If so, what weeds have you seen taking up residence there?

Awkward Botany on Outdoor Idaho (plus Send Us Your Questions)

I spend a lot time on this blog putting weeds in the spotlight, celebrating them for their successes and the unique and interesting plants they are. It’s rare that I get to share these sentiments outside of this particular venue, but I was given such an opportunity recently when asked to talk about weeds for an episode of Outdoor Idaho, a long running show on Idaho Public Television that covers Idaho’s natural history. The theme of this particular episode is wildflowers, so I was intrigued by the idea of coming on to discuss urban weeds. For many, the term “wildflowers” may invoke native plants blooming in natural areas in places far removed from the hustle and bustle of the city. But a wildflower doesn’t have to be a native plant, nor does it have to be growing in the wild. Any plant occurring naturally on its own without the assistance of humans can be a wildflower, and that includes our wild urban flora. I appreciated the chance to share this particular thought with the viewers of Outdoor Idaho.

photo credit: Jay Krajic

Along with me waxing on about weeds, the Wildflowers episode features a host of other Idahoans sharing their thoughts, expertise, and experiences with wildflowers. The episode is brief – coming in at under 30 minutes – but the producers packed in a ton of great wildflower content, and overall I found it to be an excellent representation of the flora of Idaho and a convincing argument for why we should appreciate and elevate these plants. The flora of any region is special and important in its own right, and Idaho’s flora is no different, including its weeds.

Check out Outdoor Idaho’s Wildfowers episode here.

In other news…

If you want to see more of me on the screen (and I’m not sure why you would), Sierra (a.k.a. Idaho Plant Doctor) and I are doing monthly Q&A videos in which we answer your questions about plants, gardening, pests and diseases, insects, or any other topic you might be curious about. You can tune in to those discussions on Sierra’s instagram. If you have questions of your own that you would like us to address, please leave them in the comments section below, or send them to me via the contact page or my instagram.

Weeds of Boise: Vacant Lot on West Kootenai Street

Every urban area is bound to have its share of vacant lots. These are sites that for whatever reason have been left undeveloped or were at one point developed but whose structures have since been removed. The maintenance on these lots can vary depending on who has ownership of them. Some are regularly mowed and/or treated with herbicide, while others go untouched for long periods of time. Even when there is some weed management occurring, vacant lots are locations where the urban wild flora dominates. Typically no one is coming in and removing weeds in an effort to cultivate something else, and so weeds run the show.

As with any piece of land populated by a diverse suite of wild plants, vacant lots are dynamic ecosystems, which you can read all about in the book Natural History of Vacant Lots by Matthew Vessel and Herbert Wong. The impact of humans can be seen in pretty much any ecosystem, but there are few places where that impact is more apparent than in a vacant lot. In lots located in bustling urban centers, human activity is constant. As Vessel and Wong write, “numerous ecosystem interactions are affected when humans intervene by spraying herbicides or insecticides, by trampling, by physically altering the area, or by depositing garbage and waste products.” These activities “can abruptly alter the availability and types of small habitats; this will in turn affect animal as well as plant diversity and population dynamics.” The dynamic nature of these sites is a reason why vacant lots are excellent places to familiarize yourself with the wild urban flora.

Kōura relaxing in a vacant lot

On our morning walks, Kōura and I have been visiting a small vacant lot on West Kootenai Street. We have watched as early spring weeds have come and gone, summer weeds have sprouted and taken off, perennial weeds have woken up for the year, and grass (much of which appears to have been intentionally planted) has grown tall and then been mowed with some regularity. Someone besides us is looking after this vacant lot, and it’s interesting to see how the plant community is responding. As Vessel and Wong note, “attempts to control weedy plants by mowing, cultivating, or spraying often initiate the beginning of a new cycle of growth.” For plants that are adapted to regular disturbance, measly attempts by humans to keep them in check are only minor setbacks in their path to ultimate dominance.

What follows are a few photos of some of the plants we’ve seen at the vacant lot on Kootenai Street, as well as an inventory of what can be found there. This list is not exhaustive and, as with other Weeds of Boise posts, will continue to be updated as I identify more species at this location.

dandelion (Taraxacum officinale)
grape hyacinth (Muscari armeniacum)
henbit (Lamium amplexicaule)
wild barley (Hordeum murinum) backed by cheatgrass (Bromus tectorum)
narrowleaf plantain (Plantago lanceolata) and broadleaf plantain (Plantago major)
perrennial sweet pea (Lathyrus latifolius) surrounded by redstem filaree (Erodium cicutarium)
whitetop (Lepidium sp.)
white clover (Trifolium repens)
  • Bromus tectorum (cheatgrass)
  • Capsella bursa-pastoris (shepherd’s purse)
  • Ceratocephala testiculata (bur buttercup)
  • Convolvulus arvensis (field bindweed)
  • Descurainia sophia (flixweed)
  • Draba verna (spring draba)
  • Erodium cicutarium (redstem filaree)
  • Geum urbanum (wood avens)
  • Holosteum umbellatum (jagged chickweed)
  • Hordeum murinum (wild barley)
  • Lactuca serriola (prickly lettuce)
  • Lamium amplexicaule (henbit)
  • Lathyrus latifolius (perennial sweet pea)
  • Lepidium sp. (whitetop)
  • Malva neglecta (dwarf mallow)
  • Medicago lupulina (black medic)
  • Muscari armeniacum (grape hyacinth)
  • Plantago lanceolata (narrowleaf plantain)
  • Plantago major (broadleaf plantain)
  • Poa bulbosa (bulbous bluegrass)
  • Poa pratensis (Kentucky bluegrass)
  • Rumex crispus (curly dock)
  • Taraxacum officinale (dandelion)
  • Tragopogon dubius (salsify)
  • Trifolium repens (white clover)
  • Veronica sp. (speedwell)

If you live in an urban area, chances are good there is a vacant lot near you. What have you found growing in your neighborhood vacant lot? Feel free to share in the comment section below.