Book Review: Fruit from the Sands

“By dispensing plants and animals all around the world, humans have shaped global cuisines and agricultural practices. One of the most fascinating and least-discussed episodes in this process took place along the Silk Road.” — Fruit from the Sands by Robert N. Spengler III

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My understanding of the origins of agriculture and the early years of crop domestication are cursory at best. The education I received was mostly concerned with the Fertile Crescent, as well as crops domesticated by early Americans. The Silk Road, as I understood it, was the route or routes used to move goods across Asia and into eastern Europe well after the domestication of many of the crops we know today. Other than the fact that several important crops originate there, little was ever taught to me about Central Asia and its deep connection to agriculture and crop domestication. I suppose that’s why when I picked up Fruit from the Sands by Robert N. Spengler III, published last year by University of California Press, I wasn’t entirely prepared for what I was about to read.

It wasn’t until I read a few academic reviews of Fruit from the Sands that I really started to understand. Spengler’s book is groundbreaking, and much of the research he presents is relatively new. The people of Central Asia played a monumental role in discovering and developing much of the food we grow today and some of the techniques we use to grow them, and a more complete story is finally coming to light thanks to the work of archaeologists like Spengler, as well as advances in technology that help us make sense of their findings.

This long history with agricultural development can still be seen today in the markets of Central Asia, which are loaded with countless varieties of fruits, grains, and nuts, many of which are unique to the area. Yet this abundance is also at risk. Crop varieties are being lost at an alarming rate with the expansion of industrial agriculture and the reliance on a small selection of cultivars. With that comes the loss of local agricultural knowledge. Yet, with climate change looming, diversity in agriculture is increasingly important and one of the tools necessary for maintaining an abundant and reliable food supply. Unveiling a thorough history of our species’ agricultural roots will not only give us an understanding as to how we got here, but will also help us learn from past successes and failures. Hence, the work that Spengler and others in the field of archaeobotany are doing is crucial.

To set the stage for a discussion of “the Silk Road origins of the foods we eat,” Spengler offers his definition of the Silk Road. The term is misleading because there isn’t (and never was) a single road, and the goods, which were transported in all directions across Asia, included much more than silk. In fact, some of what was transported wasn’t a good at all, but knowledge, culture, and religion. In Spengler’s words, “The Silk Road … is better thought of as a dynamic cultural phenomenon, marked by increased mobility and interconnectivity in Eurasia, which linked far-flung cultures….This network of exchange, which placed Central Asia at the center of the ancient world, looked more like the spokes of a wheel than a straight road.” Spengler also sees the origins of the Silk Road going back at least five thousand years, much earlier than many might expect.

Most of Spengler’s book is organized into chapters discussing a single crop or group of crops, beginning with grains (millet, rice, barley, wheat) then moving on to fruits, nuts, and vegetables before ending with spices, oils, and teas. Each chapter compiles massive amounts of research that can be a bit overwhelming to take in all at once. Luckily each section includes a short summary, which nicely distills the information down into something more digestible.

Spengler’s chapter on broomcorn millet (Panicum miliaceum) is particularly powerful. While in today’s world millet has largely “been reduced to a children’s breakfast food in Russia and bird food in Western Europe and America,” it was “arguably the most influential crop of the ancient world.” Originally domesticated in East Asia, “it passed along the mountain foothills of Central Asia and into Europe by the second millennium BC.” It is a high-yielding crop adapted to hot, dry conditions that, with the development of summer irrigation, could be grown year-round. These and other appealing qualities have led to an increase in the popularity of millet, so much so that 2023 will be the International Year of Millets.

The “poster child” for Spengler’s book may very well be the apple. Popular the world over, the modern apple began its journey in Central Asia. As Spengler writes, “the true ancestor of the modern apple is Malus sieversii,” and “remnant populations of wild apple trees survive in southeastern Kazakhstan today.” As the trees were brought westward, they hybridized with other wild apple species, bringing rise to the incredible diversity of apple cultivars we know today. Sadly though, most of us are only familiar with the small handful of common varieties found at our local supermarkets.

Of course, as Spengler says, “No discussion of plants on the Silk Road would be complete without the inclusion of tea (Camellia sinensis),” a topic that could produce volumes on its own. Despite the brevity of the section on tea, Spengler has some interesting things to say. One in particular involves the transport of tea to Tibet in the seventh century, where “an unquenchable thirst for tea” had developed. But the journey there was long and difficult. Fermented and oxidized tea leaves traveled best. Along the way, “the leaves were exposed to extreme cold as well as hot and humid temperatures in the lowlands, and all the time they were jostled on the backs of sweaty horses and mules.” This, however, only improved the tea, as teas exposed to such conditions “became a highly sought-after commodity among the elites.”

“In Central Asia, Mongolia, and Tibet, tea leaves were oxidized, dried, and compressed into hard bricks from which chunks could be broken off and immersed in water.” – Robert N. Spengler III in Fruit from the Sands (photo via wikimedia commons)

As dense as this book is, it’s also quite approachable. The information presented in each of the chapters is thorough enough to be textbook material, but Spengler does such a nice job summing up the main points, that there are plenty of great takeaways for the casual reader. For those wanting a deeper dive into the history of our food (which in many ways is the history of us), Spengler’s book is an excellent starting point.

More Reviews of Fruit from the Sands:

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Ground Beetles as Weed Seed Predators

As diurnal animals, we are generally unaware of the slew of animal activity that occurs during the night. Even if we were to venture out in the dark, we still wouldn’t be able to detect much. Our eyes don’t see well in the dark, and shining a bright light to see what’s going on results in chasing away those creatures that prefer darkness. We just have to trust that their out there, and in the case of ground beetles, if they’re present in our gardens we should consider ourselves lucky.

Ground beetles are in the family Carabidae and are one of the largest groups of beetles in the world with species numbering in the tens of thousands. They are largely nocturnal, so even though they are diverse and relatively abundant, we rarely get to see them. Look under a rock or log during the day, and you might see a few scurry away. Or, if you have outdoor container plants, there may be a few of them hiding out under your pots with the pillbugs. At night, they leave the comfort of their hiding places and go out on the hunt, chasing down grasshoppers, caterpillars, beetle grubs, and other arthropods, as well as slugs and snails. Much of their prey consists of common garden pests, making them an excellent form of biological control. And, as if that weren’t enough, some ground beetles also eat the seeds of common weeds.

Harpalus affinis via wikimedia commons

Depending on the species, a single ground beetle can consume around a dozen seeds per night. In general, they prefer the seeds of grasses, lambsquarters (Chenopodium album), pigweeds (Amaranthus spp.), and various plants in the mustard family (Brassicaceae). The seeds of these species are small with seed coats that are easily crushed by a beetle’s mandibles. Providing suitable habitat, avoiding insecticides, and minimizing soil disturbance (i.e. reducing or eliminating tillage) are ways that healthy ground beetle populations can be encouraged and maintained. Ground beetles prefer dense vegetation where they can hide during the daytime. Strips of bunchgrasses and herbaceous perennials planted on slightly raised bed (referred to as beetle banks) are ideal because they provide good cover and keep water from puddling up in the beetles’ hiding spots.

The freshness of weed seeds and the time of year they are available may be determining factors in whether or not ground beetles will help control weed populations. A study published in Weed Science (2014), looked at the seed preferences of Harpalus pensylvanicus, a common species of ground beetle that occurs across North America. When given the choice between year old seeds and freshly fallen seeds of giant foxtail (Setaria faberi), the beetles preferred the fresh ones. The study also found that when giant foxtail was shedding the majority of its seeds, the density of beetles was on the decline, meaning that, at least in this particular study, most of the seeds would go uneaten since fewer beetles were around when the majority of the seeds were made available. Creating habitat that extends the ground beetles’ stay is important if the goal is to maximize the number of weed seeds consumed.

Harpalus pensylvanica via wikimedia commons

Of course, the seeds of all weed species are not considered equal when it comes to ground beetle predation. Several studies have sought to determine which species ground beetles prefer, offering seeds of a variety of weeds in both laboratory and field settings and seeing what the beetles go for. Pinning this down is difficult though because there are numerous species of ground beetles, all varying in size and activity. Their abundances vary from year to year and throughout the year, as do their food sources. Since most of them are generalists, they will feed on what is available at the time. A study published in European Journal of Entomology (2003) found a correlation between seed size and body mass – small beetles were consuming small seeds and large beetles were consuming large seeds, relatively speaking.

Another study published in European Journal of Entomology (2014) compared the preferences of ground beetles in the laboratory to those in the field and found that, in both instances, the seeds of field pansy (Viola arvensis) and shepherd’s purse (Capsella bursa-pastoris) were the preferred choice. The authors note that both species have lipid-rich seeds (or high “energy content”). Might that be a reason for their preference? Or maybe it’s simply a matter of availability and “the history of individual predators and [their] previous encounters with weed seed.” After all, V. arvensis was “the most abundant seed available on the soil surface” in this particular study.

Pterostichus melanarius via wikimedia commons

A study published in PLOS One (2017), looked at the role that scent might play in seed selection by ground beetles. Three species of beetles were offered the seeds of three different weed species in the mustard family. The seeds of Brassica napus were preferred over the other two by all three beetle species. The beetles were also offered both imbibed and non-imbibed seeds of all three plants. Imbibed simply means that the seeds have taken in water, which “can result in the release of volatile compounds such as ethanol and acetaldehyde.” The researchers wondered if the odors emitted from the imbibed seeds would “affect seed discovery and ultimately, seed consumption.” This seemed to be the case as all three beetle species exhibited a preference for the imbibed seeds.

Clearly, ground beetles are fascinating study subjects, and there is still so much to learn about them and their eating habits. If indeed their presence is limiting the spread of weeds and reducing weed populations, they should be happily invited into our farms and gardens and efforts should be made to provide them with quality habitat. For a bit more about ground beetles, check out this episode of Boise Biophilia.

Further Reading:

From Cut Flower to Noxious Weed – The Story of Baby’s Breath

One of the most ubiquitous plants in cut flower arrangements hails from the steppes of Turkey and neighboring countries in Europe and Asia. It’s a perennial plant with a deep taproot and a globe-shaped, multi-branched inflorescence loaded with tiny white flowers. In full bloom it looks like a small cloud hovering above the ground. It’s airy appearance earns it the common name baby’s breath, and the attractive and durable nature of its flowers and flower stalks, both fresh and dried, have made it a staple in the floral industry. Sadly, additional traits have led to it becoming a troublesome weed outside of its native range.

baby’s breath (Gypsophila paniculata) via wikimedia commons

Gypsophila paniculata is in the family Caryophyllaceae – sharing this distinction with other cut flowers like carnations and pinks, as well as other weeds like chickweed and soapwort. At maturity and in full bloom, baby’s breath might reach three to four feet tall; however, its thick taproot extends deep into the ground as much as four times its height. Its leaves are unremarkable and sparse, found mostly towards the base of the plant and sometimes with a blue or purplish hue. The flowers are numerous and small, have a sweet scent to them (though not appreciated by everyone), and are pure white (sometimes light purple or pink).

Each flower produces just a few seeds that are black, kidney-shaped, and minuscule. Many of them drop from their fruits and land near their parent plant, but some are retained within their little capsules as the flower stalk dries and becomes brittle. Eventually a stiff breeze knocks the entire inflorescence loose and sends it tumbling across the ground. Its rounded shape makes it an effective tumbleweed, as the remaining seeds are shaken free and scattered far and wide.

baby’s breath flowers close up (via wikimedia commons)

Being a tumbleweed gives it an advantage when it comes to dispersing itself and establishing in new locations, but this is not the only trait that makes baby’s breath a successful weed. Its substantial taproot, tolerance to drought and a variety of soil conditions, and proclivity to grow along roadsides, in ditches, and abandoned fields also make it a formidable opponent. Mowing the plant down does little to stop it, as it grows right back from the crown. Best bets for control are repeated chemical treatments or digging out the top portion of the taproots. Luckily its seeds are fairly short-lived in the soil, so vigilant removal of seedlings and not allowing the plant to reproduce can help keep it in check. Baby’s breath doesn’t persist in regularly disturbed soil, so it’s generally not a problem in locations that are often cultivated like agricultural fields and gardens.

The first introductions of baby’s breath to North America occurred in the 1800’s. It was planted as an ornamental, but it wasn’t long before reports of its weedy nature were being made. One source lists Manitoba in 1887 as the location and year of the first report. It is now found growing wild across North America and is featured in the noxious weed lists in a few states, including Washington and California. It has been a particular problem on sand dunes in northwest Michigan, where it has been so successful in establishing itself that surveys have reported that 80% of all vegetation in certain areas is composed of baby’s breath.

baby’s breath in the wild (via wikimedia commons)

Invading sand dune habitats is particularly problematic because extensive stands of such a deep-rooted plant can over-stabilize the soil in an ecosystem adapted to regular wind disturbance. Plants native to the sand dunes can be negatively affected by the lack of soil movement. One species of particular concern is Pitcher’s thistle (Cirsium pitcheri), a federally threatened plant native to sand dunes along the upper Great Lakes. Much of the research on the invasive nature of baby’s breath and its removal comes from research being done in this region.

Among numerous concerns that invasive plants raise are the affects they can have on pollinator activity. Will introduced plants draw pollinators away from native plants or in some other way limit their reproductive success? Or might they help increase the number of pollinators in the area, which in turn could benefit native plants (something known as the magnet species effect)? The flowers of baby’s breath rarely self-pollinate; they require insect visitors to help move their pollen and are highly attractive to pollinating insects. A study published in the International Journal of Plant Sciences found that sand dune sites invaded by baby’s breath attracted significantly more pollinators compared to uninvaded sites, yet this did not result in more pollinator visits to Pitcher’s thistle. According to the researchers, “a reduction in pollinator visitation does not directly translate to a reduction in reproductive success,” but the findings are still a concern when it comes to the future of this threatened thistle.

Perhaps it’s no surprise that a plant commonly found in flower arrangements is also an invasive species, as so many of the plants we’ve grown for our own pleasure or use have gone on to cause problems in areas where they’ve been introduced. However, could the demand for this flower actually be a new business opportunity? Noxious weed flower bouquets anyone?

Related Posts:

Drought Tolerant Plants: Yellowhorn

A drought tolerant garden doesn’t have to be treeless. While the pickings are slim, there is a selection of trees that, once established, are well adapted to deal with extended bouts of little to no water. One such tree is yellowhorn, a species that demands to be considered for any waterwise landscape. Yellowhorn is rare in cultivation – and also restricted in its natural distribution – but perhaps that will change as word gets around about this beautiful and resilient tree.

Xanthoceras sorbifolium is native to several provinces in northern China and has been cultivated in a number of places outside of China since at least the 1800’s. Its ethnobotanical value is well understood in China. Its leaves, flowers, and seeds are edible and medicinal, and the high oil content of its seeds make them useful for the production of biofuels. Researchers are also investigating the use of yellowhorn for ecological restoration in arid habitats where desertification is a concern.

yellowhorn in bloom

Yellowhorn is the only species in the genus Xanthoceras, but is one in a long list of trees and shrubs in the Sapindaceae family – a family that now includes maples and horse chestnuts. It is considered both a large shrub and a small, multi-stemmed tree. It reaches a maximum height of about 25 feet, but arrives there at a relatively slow pace. It tolerates a variety of soil types, but like most other drought tolerant plants, it prefers soils that don’t become waterlogged easily. Its leaves are long, glossy green, and compound, consisting of 9 – 17 leaflets. The leaves persist late into the year and turn yellow in the fall. However, late spring, when the tree is covered in flowers, is when this tree puts on its real show.

Large white flowers with yellow-green centers that turn maroon or red-orange as they age are produced on racemes at the ends of branches. Small, yellow, hornlike appendages between each of the five petals of the flowers are what gives the tree its common name. Flowering lasts for a couple weeks, after which fruits form, which are about 2.5 inches wide, tough, leathery, and somewhat pear shaped. In my experience, most of the fruits are eaten by squirrels long before they get a chance to reach maturity. The ones the squirrels don’t get will persist on the tree, harden, and eventually split open to reveal several large, dark, round seeds nestled in chambers within the fruit.

To truly appreciate this tree, it must be seen in person, especially in bloom. At that point you will demand to have one (or more) in your garden. The seeds are said to be delicious, so you should give them a try if you can beat the squirrels to them. For a more thorough overview of yellowhorn, check out this article from Temperate Climate Permaculture, and for more photos of yellowhorn in bloom, check out this post from Rotary Botanical Gardens.

Squirrel nesting in yellowhorn, getting ready to go after more fruits.

All photos in this post were taken at Idaho Botanical Garden in Boise, Idaho.

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More Drought Tolerant Plants Posts:

Idaho’s Native Milkweeds (Updated)

As David Epstein said in an interview on Longform Podcast, “Any time you write about science, somethings is going to be wrong; the problem is you don’t know what it is yet, so you better be ready to update your beliefs as you learn more.” Thanks to the newly published Guide to the Native Milkweeds of Idaho by Cecilia Lynn Kinter, lead botanist for Idaho Department of Fish and Game, I’ve been made aware of some things I got wrong in the first version of this post. I appreciate being corrected though, because I want to get things right. What follows is an updated version of the original post. The most substantial change is that there are actually five milkweed species native to Idaho rather than six. Be sure to check out Kinter’s free guide to learn more about this remarkable group of plants.

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Concern for monarch butterflies has resulted in increased interest in milkweeds. Understandably so, as they are the host plants and food source for the larval stage of these migrating butterflies. But milkweeds are an impressive group of plants in their own right, and their ecological role extends far beyond a single charismatic insect. Work to save the monarch butterfly, which requires halting milkweed losses and restoring milkweed populations, will in turn provide habitat for countless other organisms. A patch of milkweed teems with life, and our pursuits to protect a single caterpillar invite us to explore that.

Asclepias – also known as the milkweeds – is a genus consisting of around 140 species, 72 of which are native to the United States and Canada. Alaska and Hawaii are the only states in the U.S. that don’t have a native species of milkweed. The ranges of some species native to the United States extend down into Mexico where there are numerous other milkweed species. Central America and South America are also home to many distinct milkweed species. Asclepias species found in southern Africa are considered by many to actually belong in the genus Gomphocarpus.

The habitats milkweeds occupy are about as diverse as the genus itself – from wetlands to prairies, from deserts to forests, and practically anywhere in between. Some species occupy disturbed and/or neglected sites like roadsides, agricultural fields, and vacant lots. For this reason they are frequently viewed as a weed; however, such populations are easily managed, and with such an important ecological role to play, they don’t deserve to be vilified in this way.

Milkweed species are not distributed across the United States evenly. Texas and Arizona are home to the highest diversity with 37 and 29 species respectively. Idaho, my home state, is on the low end with five native species. The most abundant species found in Idaho is Asclepias speciosa, commonly known as showy milkweed.

showy milkweed (Asclepias speciosa)

Showy milkweed is distributed from central U.S. westward and can be found in all western states. It occurs throughout Idaho and is easily the best place to look for monarch caterpillars. In fact, the monarch butterfly is Idaho’s state insect, thanks in part to the abundance of showy milkweed, which is frequently found growing in large colonies due to its ability to reproduce vegetatively via adventitious shoots produced on lateral roots or underground stems. Only a handful of milkweed species reproduce this way. Showy milkweed reaches up to five feet tall and has large ovate, gray-green leaves. Like all milkweed species except one (Asclepias tuberosa), its stems and leaves contain milky, latex sap. In early summer, the stems are topped with large umbrella-shaped inflorescences composed of pale pink to pink-purple flowers.

The flowers of milkweed deserve a close examination. Right away you will notice unique features not seen on most other flowers. The petals of milkweed flowers bend backwards, which would otherwise allow easy access to the flower’s sex parts if it wasn’t for a series of hoods and horns protecting them. Collectively, these hoods and horns are called the corona, which houses glands that produce abundant nectar and has a series of slits where the anthers are exposed. The pollen grains of milkweed are contained in waxy sacs called pollinia. Two pollinia are connected together by a corpusculum giving this structure a wishbone appearance. An insect visiting the flower for nectar slips its leg into the slit, and the pollen sacs become attached with the help of the corpusculum. When the insect leaves, the pollen sacs follow. Pollination is successful when the pollen sacs are inadvertently deposited on the stigmas of another flower.

Milkweed flowers are not self-fertile, so they require assistance by insects to sexually reproduce. They are not picky about who does it either, and their profuse nectar draws in all kinds of insects including bees, butterflies, moths, beetles, wasps, and ants. Certain insects – like bumble bees and other large bees – are more efficient pollinators than others. Once pollinated, seeds are formed inside a pod-like fruit called a follicle. The follicles of showy milkweed can be around 5 inches long and house dozens to hundreds of seeds. When the follicle matures, it splits open to release the seeds, which are small, brown, papery disks with a tuft of soft, white, silky hair attached. The seeds of showy milkweed go airborne in late summer.

follicles forming on showy milkweed (Asclepias speciosa)

Whorled or narrowleaf milkweed (Asclepias fascicularis) occurs across western and southern Idaho. Its distribution continues into neighboring states. It is adapted to dry locations, but can be found in a variety of habitats. Like showy milkweed, it spreads rhizomatously as well as by seed. It’s a wispy plant that reaches one to three feet tall and occasionally taller. It has long, narrow leaves and produces tight clusters of greenish-white to pink-purple flowers. Its seed pods are long and slender and its seeds are about 1/4 inch long.

flowers of narrowleaf milkweed (Asclepias fascicularis)

seeds escaping from the follicle of narrowleaf milkweed (Asclepias fascicularis)

Swamp or rose milkweed (Asclepias incarnata) is more common east of Idaho, but occurs occasionally in southwestern Idaho. As its common name suggests, it prefers moist soils and is found in wetlands, wet meadows, and along streambanks. It can spread rhizomatously, but generally doesn’t spread very far. It reaches up to four feet tall, has deep green, lance-shaped leaves, and produces attractive, fragrant, pink to mauve, dome-shaped flower heads at the tops of its stems. Its seed pods are narrow and around 3 inches long.

swamp milkweed (Asclepias incarnata)

Asclepias cryptoceras ssp. davisii, or Davis’s milkweed, is a low-growing, drought-adapted, diminutive species that occurs in southwestern Idaho. It has round or oval-shaped leaves and produces flowers on a short stalk. The flowers have white or cream-colored petals and pink-purple hoods. The range of Asclepias cryptoceras – commonly known as pallid milkweed or jewel milkweed – extends beyond Idaho’s borders into Oregon and Nevada, creeping north into Washington and south into California. Another subspecies – cryptoceras – can be found in Nevada, Utah, and their bordering states.

Davis’s milkweed (Asclepias cryptoceras ssp. davisii)

The final species is rare in Idaho, as Idaho sits at the top of its native range. Asclepias asperula ssp. asperula, or spider milkweed, has a single documented location in Franklin County (southeastern Idaho). Keep your eyes peeled though, because this plant may occur elsewhere, either in Franklin County or neighboring counties. It grows up to two feet tall with an upright or sprawling habit and produces clusters of white to green-yellow flowers with maroon highlights. Its common name comes from the crab spiders frequently found hunting in its flower heads.

A sixth species, horsetail milkweed (Asclepias subverticillata), has been falsely reported in Idaho. Collections previously labeled as A. subverticillata have been determined to actually be the similar looking A. fascicularis.

Using Weeds: Soapwort

Over the past year or so I have written about several edible weeds in an effort to highlight useful weeds. However, weeds don’t have to be edible to be useful. In fact, many weeds are most certainly not edible, but that doesn’t mean they are of no use to humans. Soapwort, for example, is poisonous, and while it does have a history of being used internally as medicine, ingesting it is not advised and should only be done under the direction of a doctor. A much less risky activity would be to make soap out of it.

soapwort (Saponaria officinalis)

Saponaria officinalis, commonly known as bouncing bet, hedge pink, fuller’s herb, scourwort, and soapweed or soapwort, is an herbaceous perennial native to Europe. It has been planted widely in flower beds and herb gardens outside of its native range, desired both for its beauty and utility. Capitalizing on our appreciation for it, soapwort has expanded beyond our garden borders and into natural areas, as well as vacant lots, roadsides, and other neglected spaces. Even in a garden setting it can be a bit of a bully, especially if ignored for a season or two.

The stems of soapwort grow to about two feet tall, are unbranched, and sometimes tinged with pink, purple, or red. The leaves are oblong and oppositely-arranged, and their bases form prominent collars around the stems. Showy clusters of flowers are found atop the stems throughout the summer. Like other flowers in the pink family (Caryophyllaceae), they are cigar-shaped at the base and opened wide at the end, showing off 5 distinct petals with notches at their tips. The petals of soapwort flowers bend backwards, with their sex parts protruding outwards. In his description of the flowers, John Eastman remarks in The Book of Field and Roadside that “the reflexed petals surrounding the sexual organs give the impression of flagrant thrust; this is a gaudy, unshy flower.”

collared stem of soapwort (Saponaria officinalis)

The fragrant flowers are pink to white in color. They open in the evening and remain open for a few short days. In an individual flower, pollen matures and is mostly shed before the stigma is ready to accept it. This helps reduce the chance of self-pollination. Cross pollination occurs with the assistance of moths who visit the flowers at night, as well as bees and other flower-visiting insects that come along during the daytime. Soapwort fruits are oval capsules containing as many as 500 kidney-shaped seeds. Seeds aren’t essential to the plants spread though, as much of its colonization occurs via vigorous rhizomes.

In fact, vegetative reproduction is the means by which soapwort forms such expansive, thick patches. It also helps that it’s poisonous. The saponins – its soap making compounds – that it produces in its roots, shoots, and leaves deter most insects and other animals from eating it. It has a reputation for poisoning horses, cows, and other livestock, and so is unwelcome in pastures and rangelands. Saponins are also poisonous to fish, so growing soapwort near fish ponds is not advised.

soapwort (Saponaria officinalis)

Soapwort occurs in a variety of soils including sandy, dry, and rocky sites and is surprisingly drough-tolerant, fine qualities to have when colonizing neglected sites. While most other organisms ignore soapwort, it has a friend in humans. Eastman sums this up well: “Soapwort’s most important associate – as is true of most plants we label weeds – is undoubtedly humankind, without whose helpful interventions the plant would surely be much rarer than it is.”

I made a soapy liquid out of soapwort by following a recipe that can be found on various blogs and websites by searching “saponaria soap recipe.” Basically it’s a cup of fresh leaves and stems along with a cup of dried leaves and stems added to a quart of distilled water brought to a boil. After simmering for 15 minutes and then allowing it to cool, strain the mixture through cheese cloth, and it’s ready to go.

This gentle but effective soap can be used for cleaning countertops and other surfaces, as well as dishes, fabrics, and skin. Several sources say it is particularly useful for cleaning delicate fabrics. Sierra and I both found it to have a cooked cabbage or spinach scent to it. This can be masked by adding a few drops of essential oil. Despite its odd aroma, both Sierra and I were impressed by its cleansing power and plan to use it more often.

dried leaves of soapwort

soapwort soap

Selections from the Boise Biophilia Archives

For a little over a year now, I’ve been doing a tiny radio show with a friend of mine named Casey O’leary. The show is called Boise Biophilia and airs weekly on Radio Boise. On the show we each take about a minute to talk about something biology or ecology related that listeners in our local area can relate to. Our goal is to encourage listeners to get outside and explore the natural world. It’s fascinating after all! After the shows air, I post them on our website and Soundcloud page for all to hear.

We are not professional broadcasters by any means. Heck, I’m not a huge fan of talking in general, much less when a microphone is involved and a recording is being made. But Casey and I both love spreading the word about nerdy nature topics, and Casey’s enthusiasm for the project helps keep me involved. We’ve recorded nearly 70 episodes so far and are thrilled to know that they are out there in the world for people to experience. What follows is a sampling of some of the episodes we have recorded over the last 16 months. Some of our topics and comments are inside baseball for people living in the Treasure Valley, but there’s plenty there for outsiders to enjoy as well.

Something you will surely note upon your first listen is the scattering of interesting sound effects and off the wall edits in each of the episodes. Those come thanks to Speedy of Radio Boise who helps us edit our show. Without Speedy, the show wouldn’t be nearly as fun to listen to, so we are grateful for the work he does.

Boise Biophilia logo designed by Sierra Laverty

In this episode, Casey and I explore the world of leaf litter. Where do all the leaves go after they fall? Who are the players involved in decomposition, and what are they up to out there?

 

In this episode, Casey gets into our region’s complicated system of water rights, while I dive into something equally complex and intense – life inside of a sagebrush gall.

 

In this episode, I talk about dead bees and other insects trapped and dangling from milkweed flowers, and Casey discusses goatheads (a.k.a. puncture vine or Tribulus terrestris) in honor of Boise’s nascent summer celebration, Goathead Fest.

 

As much as I love plants, I have to admit that some of our best episodes are insect themed. Their lives are so dramatic, and this episode illustrates that.

 

The insect drama continues in this episode in which I describe how ant lions capture and consume their prey. Since we recorded this around Halloween, Casey offers a particularly spooky bit about garlic.

 

If you follow Awkward Botany, you know that one of my favorite topics is weeds. In this episode, I cover tumbleweeds, an iconic western weed that has been known to do some real damage. Casey introduces us to Canada geese, which are similar to weeds in their, at times, overabundance and ability to spawn strong opinions in the people they share space with.

 

In this episode, I explain the phenomenon of marcescence, and Casey gives some great advice about growing onions from seed.

 

And finally, in the spring you can’t get by without talking about bulbs at some point. This episode is an introduction to geophytes. Casey breaks down the basics, while I list some specific geophytes native to our Boise Foothills.

 

Field Trip: Orton Botanical Garden

In the inaugural year of this blog, I wrote a short post about a visit to Plantasia Cactus Gardens, a botanical garden in Twin Falls, Idaho that specializes in cold hardy cactus and other succulents. I finally made a return visit all these years later (thanks to a co-worker who organized the trip). Back in 2013, the garden was private but open to the public by appointment. Today, the garden is still open by appointment but is now a 501(c)(3) non-profit organization with a new name: Orton Botanical Garden.

With the name change and non-profit status comes a new mission statement. The garden has been an impressive display of cold hardy cactus and succulents along with native and drought-tolerant plants for many years now. It has also long been a resource for educating visitors on the importance of these plants, as well as the importance of water conservation through water efficient landscaping. So the mission statement isn’t necessarily a new direction, but rather an affirmation of what this garden has done so well for years. Few gardens are doing cold hardy, drought-tolerant plants at the level that Orton Botanical Garden is.

Many of the plants at Orton Botanical Garden are made available to the public for purchase through an annual plant sale in May, as well as through an online store. This is another great service because sourcing some of these plants is not easy, and this one of the few places they can be found for sale.

Wherever you live in the world, this is a garden that should be on your bucket list. Even at a mere 5 acres in size, one could easily spend hours exploring it, and each visit reveals something new. What follows is just a small sampling of the things you will find there.

Toroweap hedgehog (Echinocereus coccineus var. toroweapensis)

scarlet hedgehog (Echinocereus coccineus var. coccineus)

White Sands kingcup cactus (Echinocereus triglochidiatus var. triglochidiatus)

Orcutt’s foxtail cactus (Escobaria orcuttii var. koenigii)

a peak down a shallow gully flanked by cholla (Cylindropuntia spp.)

Colorado hookless cactus (Sclerocactus glaucus)

Fremont’s mahonia (Mahonia fremontii)

close up of Fremont’s mahonia (Mahonia fremontii)

spiny pillow (Ptilotrichum spinosum)

hairstreak on cliff fendlerbush (Fendlera rupicola)

Utah sweetvetch (Hedysarum boreale)

Several species of buckwheats were in bloom, including this Railroad Canyon buckwheat (Eriogonum soliceps).

There were also quite a few penstemon species blooming, like this sidebells penstemon (Penstemon secundiflorus).

More Awkward Botany Field Trips:

Drought Tolerant Plants: Ice Plants

Among the various strategies plants have for tolerating drought, succulence is easily one of the most common and most successful. A recent article in the new open source journal, Plants People Planet, explores the world of succulent plants, commenting on, among other things, their evolution and extent. At least 83 plant families contain succulent species, and as many as 3-5% of flowering plants are considered succulents.

Succulence involves the storage of water in the cells of one or more plant organs (i.e. roots, stems, or leaves) as a mechanism for surviving drought. One way that succulent species differ is the location and nature of this storage. Some succulents are all cell succulents, meaning that the cells involved in storing water are also involved in carrying out photosynthesis. Other succulents are storage succulents. They have specific cells called hydrenchyma designed for storing water. These cells are non-photosynthetic.

Plants in the family Aizoaceae are storage succulents. Commonly known as the ice plant or carpet weed family, this family consists of hundreds of species and is mainly distributed throughout a region of South Africa known as Succulent Karoo. Species in this family earn the name ice plant thanks to numerous bladder-like cells or hairs that cover their leaves and stems causing them to sparkle or glimmer in the light. Aizoaceae diversity is incredible, and while this post focuses mainly on a few select species, it’s worth browsing through the profiles listed on World of Succulents to appreciate the breadth of forms these plants can take.

common ice plant (Mesembryanthemum crystallinum)

Among many interesting features that plants in this family possess, one particularly fun thing to note is that their flowers, which are unapologetically showy, lack true petals. Instead, what appear as a series of flat, thin petals encircling the center of the flower are actually modified stamens. They act as petals – drawing in pollinators with their bright colors – so calling them petals is acceptable, just not entirely accurate. Another fun fact is that seed pods of plants in Aizoaceae are often hygrochastic – upon getting wet they burst open and expel their seeds.

The photosynthetic pathway in succulents is generally different compared to other plants. Instead of the common C3 pathway, succulents use a pathway called CAM, or Crassulacean Acid Metabolism. CAM photosynthesis is similar to C4 photosynthesis – another photosynthetic pathway common among drought tolerant plants – in that it uses PEP carboxylase instead of rubisco to fix carbon and then sends it to a separate cell to be converted into sugars. In C4 photosynthesis, this whole process happens during the day. CAM photosynthesis differs in that it fixes carbon during the night and then sends it to another cell to be converted into sugars during the day. Fixing carbon at night is a way to avoid the water loss that occurs when collecting carbon dioxide during the daytime.

In discussing Aizoaceae, this is an important consideration because, unlike many other succulents, plants in this family don’t rely solely on CAM photosynthesis, but can instead switch back and forth between C3 and CAM. The ability to do this is likely because they are storage succulents rather than all cell succulents, and because they can do this, they are very efficient carbon fixers.

flowers fading on purple ice plant (Delosperma cooperi)

I live in a region where winter temperatures can dip into the single digits (°F) and sometimes lower,  so my familiarity with ice plants is with cold hardy species and cultivars of the genus Delosperma. If you are familiar with this group of plants, it is most likely thanks to the Plant Select program based in Colorado, particularly the work of Mr. Delosperma himself, Panayoti Kelaidis. Several Delosperma species are cold hardy in the Intermountain West. Thanks to their promiscuous nature, numerous crosses have occurred between species and varieties, resulting in a wide array of flower colors. And speaking of their flowers, the glistening leaves of Delosperma have nothing on their shimmering flowers, some of which may have the ability to temporarily blind you if you’re not careful. Sun is essential though, as they usually close up when shaded.

The cold hardy ice plants of the Delosperma genus are all groundcovers, maintaining a low and creeping profile. Some creep further than others. They are generally not fond of heavy clay soils, and instead prefer soil with good drainage. During the hot, dry days of summer, they appreciate a little water now and then, but watering should be cut off at the end of summer so that they aren’t sitting in saturated soils as winter approaches. They love the sun and will generally flower from late spring throughout the summer. Of course, thanks to their interesting foliage, they catch the eye and provide interest in the garden even when they aren’t flowering.

Fire Spinner® ice plant (Delosperma ‘P001S’)

Within Aizoaceae there are several species that go by the name ice plant that are not so cold hardy. Some are grown as house plants, while others are common in gardens. Still others, like Carpobrotus edulis, were once employed by land managers in California to help control erosion. However, like a number of species introduced for this purpose, C. edulis (commonly known as highway ice plant or hottentot fig) has made itself at home in areas where it wasn’t invited. It has become particularly problematic in coastal ecosystems, spreading quickly across sandy soils and outcompeting native plants. Despite being brought in to control erosion, it actually causes erosion in steep, sandy areas when its carpet-like growth becomes heavy with water and begins sliding down the hill.

highway ice plant (Carpbrotus edulis) carpeting a slope near San Diego – photo credit: Sierra Laverty

Introducing plants to our gardens that come to us from the other side of the globe should be done with caution and care. We don’t want to be responsible for the next invasive species. Since ice plant species have become problematic in California, should we be concerned about cold hardy delospermas? In trialing their plants, invasive qualities are among those that the Plant Select program watches out for, and delospermas seem pretty safe. However, as Kelaidis observes in a blog post from 2014, we should remain vigilant.

Select Resources:

Investigating the Soil Seed Bank

Near the top of the world, deep inside a snow-covered mountain located on a Norwegian island, a vault houses nearly a million packets of seeds sent in from around the world. The purpose of the Svalbard Global Seed Vault is to maintain collections of crop seeds to ensure that these important species and varieties are not lost to neglect or catastrophe. In this way, our food supply is made more secure, buffered against the unpredictability of the future. Seed banks like this can be found around the world and are essential resources for plant conservation. While some, like Svalbard, are in the business of preserving crop species, others, like the Millennium Seed Bank, are focused on preserving seeds of plants found in the wild.

Svalbard Global Seed Vault via wikimedida commons

Outside of human-built seed banks, many plants maintain their own seed banks in the soil where they grow. This is the soil seed bank, a term that refers to either a collection of seeds from numerous plant species or, simply, the seeds of a single species. All seed bearing plants pass through a period as a seed waiting for the chance to germinate. Some do this quickly, as soon as the opportunity arises, while others wait, sometimes for many years, before germinating. Plants whose seeds germinate quickly, generally do not maintain a seed bank. However, seeds that don’t germinate right away and become incorporated in the soil make up what is known as a persistent soil seed bank.

A seed is a tiny plant encased in a protective layer. Germination is not the birth of a plant; rather, the plant was born when the seed was formed. The dispersal of seeds is both a spatial and temporal phenomenon. First the seed gets to where it’s going via wind, water, gravity, animal assistance, or some other means. Then it waits for a good opportunity to sprout. A seed lying in wait in the soil seed bank is an example of dispersal through time. Years can pass before the seed germinates, and when it does, the plant joins the above ground plant community.

Because seeds are living plants, seeds found in the soil seed bank are members of a plant community, even though they are virtually invisible and hard to account for. Often, the above ground plant community does not represent the population of seeds found in the soil below. Conversely, seeds in a seed bank may not be representative of the plants growing above them. This is because, as mentioned earlier, not all plant species maintain soil seed banks, and those that do have differences in how long their seeds remain viable. Depending on which stage of ecological succession the plant community is in, the collection of seeds below and the plants growing above can look quite different.

Soil seed banks are difficult to study. The only way to know what is truly there is to dig up the soil and either extract all the seeds or encourage them to germinate. Thanks to ecologists like Ken Thompson, who have studied seed banks extensively for many years, there is still a lot we can say about them. First, for the seeds of a plant to persist in the soil, they must become incorporated. Few seeds can bury themselves, so those with traits that make it easy for them to slip down through the soil will have a greater chance of being buried. Thompson’s studies have shown that “persistent seeds tend to be small and compact, while short-lived seeds are normally larger and either flattened or elongate.” Persistent seeds generally weigh less than 3 milligrams and tend to lack appendages like awns that can prevent them from working their way into the soil.

The seeds of moth mullein (Verbascum blattaria) are tiny and compact and known to persist in the soil for decades as revealed in Dr. Beal’s seed viability experiment. (photo credit: wikimedia commons)

Slipping into cracks in the soil is a major way seeds move through the soil profile, but it isn’t the only way. In a study published in New Phytologist, Thompson suggests that “the association between small seeds and possession of a seed bank owes much to the activities of earthworms,” who ingest seeds at the surface and deposit them underground. Later, they may even bring them back up the same way. Ants also play a role in seed burial, as well as humans and their various activities. Some seeds, like those of Avena fatua and Erodium spp., have specialized appendages that actually help work the seeds into the soil.

Not remaining on the soil surface keeps seeds from either germinating, being eaten, or being transported away to another site. Avoiding these things, they become part of the soil seed bank. But burial is only part of the story. In an article published in Functional Ecology, Thompson et al. state that burial is “an essential prelude to persistence,” but other factors like “germination requirements, dormancy mechanisms, and resistance to pathogens also contribute to persistence.” If a buried seed rots away or germinates too early, its days as a member of the soil seed bank are cut short.

The seeds of redstem filare (Erodium circutarium) have long awns that start out straight, then coil up, straighten out, and coil up again with changes in humidity. This action helps drill the seeds into the soil. (photo credit: wikimedia commons)

Soil seed banks can be found wherever plants are found – from natural areas to agricultural fields, and even in our own backyards. Thompson and others carried out a study of the soil seed banks of backyard gardens in Sheffield, UK. They collected 6 soil cores each (down to 10 centimeters deep) from 56 different gardens, and grew out the seeds found in each core to identify them. Most of the seeds recovered were from species known to have persistent seed banks, and to no surprise, the seed banks were dominated by short-lived, weedy species. The seeds were also found to be fairly evenly distributed throughout the soil cores. On this note, Thompson et al. remarked that due to “the highly disturbed nature of most gardens, regular cultivation probably ensures that seeds rapidly become distributed throughout the top 10 centimeters of soil.”

Like the seed banks we build to preserve plant species for the future, soil seed banks are an essential long-term survival strategy for many plant species. They are also an important consideration when it comes to managing weeds, which is something we will get into in a future post.