Seed Oddities: Apomixis and Polyembryony

Plants have uncanny ways of reproducing themselves that are unparalleled by most other living things. Offshoots of themselves can be made by sending out modified stems above or beneath the ground which develop roots and shoots (new plants) at various points along the way. Various other underground stem and root structures can also give rise to new plants. Small sections of root, stem, or leaf can, under the right conditions, push out new plantlets in a fashion that seems otherworldly. (Picture chopping off a bit of your finger and growing a whole new you from it.)

These are some of the ways in which plants reproduce asexually, and it’s kind of freaky if you think about it. Plants can clone themselves. But one major disadvantage of reproducing this way is that clonal offspring are genetically identical to the parent plant, which truncates any advantage that might be gained by genetic mixing between two separate plants. For one, it means that a plant population composed of all clones is at risk of being wiped out if something in the environment comes along (such as a disease or change in climate) and none of the plants in the population have adapted any sort of resistance to it.

New plants forming along the lateral stems of Ranunculus flammula – via wikimedia commons

That’s where seeds come in. Seeds are produced sexually, when the gametes of one plant fuse with the gametes of another. Genetic recombination occurs, and a genetically unique individual is born, housed within a seed. Unless, of course, that seed is produced asexually. Then the seed is a clone, and we’re back to where we started.

Apomixis is the process by which seeds are produced asexually. In flowering plants, this means that viable seeds are formed even when flowers haven’t been pollinated. In some cases, pollination stimulates apomixis or is required to produce endosperm; but either way, the result is the same: an embryo containing an exact copy of the genes of its single parent plant.

To understand this process, it’s important to familiarize yourself with the basic anatomy of an ovule, the part of a plant where embryos are formed and which ultimately becomes a seed. In gymnosperms, ovules sit inside cones; in angiosperms, they are surrounded by an ovary. The wall of the ovule is called an integument. A small opening at the top of the ovule, known as a micropyle, is where the pollen tube enters. Diploid cells of the nucellus compose the interior of the ovule, and within the nucellus resides the megasporocyte, which is where meiosis occurs and egg cells are produced. In sexual reproduction, a germ cell introduced through the pollen tube fuses with the egg cell to form a zygote and eventually an embryo. In the case of apomixis, the fusion of germ cells isn’t necessary for an embryo to form.

ovule anatomy via wikimedia commons

There are three main types of apomixis: diplospory, apospory, and adventitious embryony. In diplospory, the megasporocyte skips meiosis and produces diploid cells instead of haploid cells (germ cells). These unreduced cells go on to form an embryo inside of the embryo sac, just like an egg cell would if it had been fertilized with a pollen cell. Additional unreduced cells go on to form endosperm, and the ovule then matures into a seed. This type of apomixis is common in dandelions (Taraxacum officinale). As much as bees love visiting dandelion flowers, their pollination services are not required for the production of viable seeds. Yet another reason you are stuck with dandelions in your yard whether you like it or not.

In apospory, an embryo develops inside of an embryo sac that has been formed from cells in the nucellus. Embryo development within the megasporocyte is bypassed; however, pollination is usually necessary for endosperm to form. Plant species in the grass family commonly produce seeds using this type of apomixis.

Adventitous embryony is also known as sporophytic apomixis because an embryo is formed outside of an embryo sac. Cells from either the integument or the nucellus produce an embryo vegetatively. In this case, a sexually produced embryo can form along with several vegetatively produced embryos. Extra embryos die off and a single, surviving embryo is left inside the mature seed. But not always. Two or more embryos occasionally survive, including the sexually produced one. The mature seed then consists of multiple embryos. This phenomenon is called polyembryony and is common in citrus and mangoes. When it comes to plant breeding, polyembryony is incredibly useful because the asexually derived seedlings are exact copies of their parent, which means the desirable traits of a specific cultivar are retained.

Depiction of seed with three viable embryos after germination.

Polyembryony can occur in a number of ways, and not always as a result of apomixis. In some species, additional embryos “bud off” from the sexually produced embryo. This is called cleavage polyembryony and is known to happen frequently in the pine family (Pinaceae), as well as other plant families. Another common form of polyembryony in gymnosperms is simple polyembryony, in which several egg cells in a single ovule are fertilized resulting in the development of multiple embryos. This doesn’t always mean there will be multiple seedlings sprouting from a single seed. Most embryos usually fail to mature, and only one prevails. However, sometimes more than one survives, and if you’re lucky, you’ll find a seed with multiple plant babies pushing out from the seed coat.

Up Next: Vivipary!

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Inside of a Seed: Gymnosperms

“Every tree has to stay where it put down roots as a seedling. However, it can reproduce, and in that brief moment when tree embryos are still packed into seeds, they are free. The moment they fall from the tree, the journey can begin.” — The Hidden Life of Trees by Peter Wohlleben

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Seed plants – also known as spermatophytes – make up the largest group of plants on earth. Seed plants consist of five divisions, and among them the angiosperm division (a.k.a. flowering plants) dominates in its number of species. The four remaining divisions are referred to collectively as gymnosperms. This incudes the cycads (Cycadophyta), Ginkgo biloba (the only living species in the division Ginkgophyta), gnetophytes (Gnetophyta), and the conifers (Coniferophyta). Conifers are by far the largest and most widespread gymnosperm division.

Angiosperms and gymnosperms have different evolutionary histories, resulting in their distinct genetic and morphological differences. That being said, an overly-simplistic way of differentiating the two groups is to say that, while both groups produce seeds, angiosperms produce flowers and fruits while gymnosperms produce pollen cones and seed cones. There are always exceptions (Ginkgo biloba, for example, doesn’t produce cones), but for the most part, this is the case.

Pollen cones (top) and seed cones (bottom) of mugo pine (Pinus mugo) via wikimedia commons

Sexual reproduction in gymnosperms follows a familiar pattern. Pollen, which contains the male sex cells, is produced in pollen cones, which are essentially miniature branches with modified leaves called scales that house the male reproductive organs. Mature pollen is shed and carried away by the wind. Lucky pollen grains make their way to the female cones, which are also modified branchlets, but are a bit more complex. Scales sit atop bracts, and on top of the scales are ovules – the female reproductive structures. During fertilization, the bracts open to collect pollen and then close as the seed develops.

When pollen lands on an ovule it forms pollen tubes that help direct the male sex cells to the egg cells inside. The process is similar to pollen tubes extending down the style of a flower. In flowering plants, additional pollen cells combine with cells in the ovule to produce endosperm, a storage tissue that feeds the growing embryo. This doesn’t happen in gymnosperms. Instead, haploid cells within the ovule develop into storage tissue and go on to serve the same role.

The ovule eventually matures into a seed, and the cone opens to release it. The seed sits atop the scale rather than enclosed within a fruit, as it would be in an angiosperm. For this reason gymnosperms are said to have naked seeds. The development of seeds can also be much slower in gymnosperms compared to angiosperms. In some species, seeds don’t reach maturity for as long as two years.

Seed cones and winged seeds of mugo pine (Pinus mugo) via wikimedia commons

Seeds in the genus Pinus are excellent representations of typical gymnosperm seeds. Their basic components are essentially identical to the seeds of angiosperms. The seed coat is also referred to as an integument. It was once the outer covering of the ovule and has developed into the seed covering. A micropyle is sometimes visible on the seed and is the location where the pollen cells entered the ovule. The storage tissue, as mentioned above, is composed of female haploid cells that matured into storage tissue in the ovule. Like angiosperms, the embryo is composed of the radicle (embryonic root), the hypocotyl (embryonic shoot), and cotyledons (embryonic leaves).

Angiosperms can be divided into monocotyledons and dicotyledons according to the number of cotyledons their embryos have (monocots have one, dicots have two). Gymnosperms are considered multi-cotyledonous because, depending on the species, they can have a few to many cotyledons.

Seedling of Swiss pine (Pinus cembra) showing multiple cotyledons via wikimedia commons

For the sake of this introduction to gymnosperm seeds, I have offered a simple overview of the production of seeds in the conifer division. Sexual reproduction and seed formation in the other three gymnosperm divisions is a similar story but varies according to species. Even within the conifers there are differences. For example, the “seed cones” of several gymnosperm species can actually be quite fruit-like, which serves to attract animals to aid in seed dispersal. Also, the pollen of gymnosperms is often thought of as being wind dispersed (and occasionally water dispersed in the case of Ginkgo biloba and some cycads); however, researchers are continuing to discover the pivotal role that insects play in the transfer of pollen for many cycad species, just as they do for so many species of angiosperms.

All of this to say that Botany 101 is simply a window into what is undoubtedly an incredibly diverse and endlessly fascinating group of organisms, and that, as with all branches of science, there is still so much to discover.

Inside of a Seed: Two Monocots

“Seeds are travelers in space and time – small packages of DNA, protein, and starch that can move over long distances and remain viable for hundreds of years. These packages have everything they need not only to survive, but also to grow into a plant when they encounter the right conditions.”      The Book of Seeds by Paul Smith

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As illustrated in last week’s post, the mature seeds of dicots – depending on the species – can be either with or without endosperm (a starchy food packet that feeds a growing seedling upon germination). Seeds without endosperm store these essential sugars in their cotyledons. Monocotyledons (or monocots, for short) are a group of flowering plants (i.e. angiosperms) whose seedlings are composed of a single cotyledon. With the exception of orchids, the seeds of monocots always contain endosperm.

The first of two examples of monocot seeds is the common onion (Allium cepa). The embryo in this seed sits curled up, surrounded by endosperm inside of a durable seed coat.

If you have ever sown onion seeds, you have watched as the single, grass-like cotyledon emerges from the soil. The seed coat often remains attached to the tip of the cotyledon like a little helmet as it stretches out towards the sky. Soon the first true leaf appears, pushing out from the base of the cotyledon. The source of this first leaf is the plumule hidden within the cotyledon.

The fruit of plants in the grass family – including cereal grains like wheat, oats, barley, rice, and corn – is called a caryopsis. In this type of fruit, the fruit wall (or pericarp) is fused to the seed coat, making the fruit indistinguishable from the seed. The embryos in these seeds are highly developed, with a few more discernible parts. A simplified diagram of a corn seed (Zea mays) is shown below. Each kernel of corn on a cob is a caryopsis. These relatively large seeds are great for demonstrating the anatomy of seeds in the grass family.

In these seeds there is an additional layer of endosperm called aleurone, which is rich in protein and composed of living cells. The cells of the adjacent endosperm are not alive and are composed of starch. The embryo consists of several parts, including the cotyledon (which, in the grass family, is also called a scuttelum), coleoptile, plumule, radicle, and coleorhiza. The coleoptile is a sheath that protects the emerging shoot as it pushes up through the soil. The plumule is the growing point for the first shoots and leaves, and the radicle is the beginning of the root system. The emerging root is protected by a root cap called a calyptra and a sheath called a coleorhiza.

Germination begins with the coleorhiza pushing through the pericarp. It is quickly followed by the radicle growing through the coleorhiza. As the embryo emerges, a signal is sent to the endosperm to start feeding the growing baby corn plant, giving it a head start until it can make its own food via photosynthesis.

corn seeds (Zea mays)

Up Next: We’ll take an inside look at the seeds of gymnosperms.

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Inside of a Seed: Two Dicots

“A seed is a living thing that embodies roots, stems, leaves, and fruit in an embryonic state and retains the ability to convert the sun’s energy into a source of food.” — Seedtime by Scott Chaskey

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Few things are more miraculous than seeds. Within them is a living plant in embryonic form. Under the right conditions, these tiny objects expand, pushing out the beginnings of the most minuscule weed to the most humongous tree. Looking at these otherwise unassuming specks, you would hardly guess that they held such potential.

Housed in a seed is the genetic material necessary for growth and reproduction, along with some stored sugars to get the plant started. All of this is enclosed in a protective case. It is a rare moment in a plant’s life – a time when it isn’t rooted in place and can, for a brief period, move around. With the help of agents like wind, water, and animals it can travel anywhere in the world, venturing as far as inches or miles from its parent plant. As long as it finds a suitable place to grow, its voyage is not in vain.

Seeds are the result of sexual reproduction in plants (with rare exceptions, which we will cover in a future post). After pollination, a pollen grain sends three haploid cells into the ovule of a flower. These cells unite with the haploid cells found within. One germ cell from the pollen grain goes to the formation of an embryo, while the other two cells help form endosperm, the food source for the developing embryo. The wall of the ovule becomes the outer layer of the seed, known as the seed coat or testa. The seed matures as the fruit it is nested in ripens. Eventually, the fetal plant within the seed is ready to find a new home.

Seed heads of rubber rabbitbrush (Ericameria nauseosa) – the fuzzy pappus attached to the fruits allows seeds to float in the breeze and travel away from their parent plant.

As with so many things in biology, there is no single type of seed. When it comes to seed anatomy, most seeds consist of the same basic components, but each species of plant has its own unique seed. In fact, a well-trained taxonomist can identify plants simply by observing their seeds. With such a wide variety of seeds, it is difficult to organize them into discrete categories, but we still try. What follows is an introduction to two types of seeds – endospermic and non-endospermic – using two basic examples.

The first thing you should know about these two examples is that both species are dicotyledons (or dicots, for short). This means that when the baby plant emerges, it has two cotyledons, which are also called embryonic leaves because they look like little leaves. All flowering plants have been divided into two groups based on the number of cotyledons they have, the second group being the monocotolydons (or monocots) which have only one cotyledon. This is an old-fashioned way to classify plants, but it is still useful in some instances.

Endospermic Seeds

The seeds of the castor bean plant (Ricinus communis) are endospermic seeds. This means that they retain the endosperm that was formed when two pollen grain cells joined up with the haploid cell in the ovule. The endosperm will help feed the growing embryo as it germinates. The two cotyledons are visible within the seed, but they are thin and broad, leaving plenty of space in the seed for the endosperm. The cotyledons are part of the embryo and are attached to the radicle, which is the embryonic root. The radicle is the first thing to emerge from the seed upon germination. The area between the radicle and the cotyledon is known as the hypocotyl. It becomes the stem of the germinating seedling.

An elaisome is attached to the outside of the seed coat of castor bean seeds. This fleshy, nutrient-rich appendage is particularly attractive to ants. They carry the seeds back to their colony and feed the elaisome to their young. The seeds, however, remain unconsumed. In this way, the ants aid in the seeds’ dispersal.

seeds of castor beans (Ricinus communis)

Non-endospermic Seeds

The seeds of plants in the bean family (Fabaceae) are non-endospermic seeds. This means that as the embryo develops, it uses up the majority of the endosperm within the seed. The food necessary for the seedling to get its start is all stored in its cotyledons. The common pea (Pisum sativum) is a good example of this. The embryo – which consists of the cotyledons, plumula (or plumule), hypocotyl, and radicle – takes up all available space inside of the seed coat. After germination, as the seedling develops, the plumule appears above the cotyledons and is the growing point for the first true leaves and stems.

seeds of the common pea (Pisum sativum)

In future posts, we will look at a few other types of seeds, as well as discuss various other seed-related topics. If you have a story to share about seeds, please do so in the comment section below.

Field Trip: Bergius Botanic Garden and Copenhagen Botanical Garden

There are very few downsides to working at a botanical garden, but one of them is that the growing season can be so busy that taking time off to visit other botanical gardens when they are at their peak is challenging. Case in point, my visit to Alaska Botanical Garden last October. Another case in point, this December’s visit to a couple of gardens in Scandinavia.

That’s right, Sierra and I took a long (and much needed) break from work and headed to the other side of the world for some fun in the occasional sun of Denmark and Sweden. While we were there we visited two botanical gardens, one in Stockholm and the other in Copenhagen. Considering we were there in December, we were impressed by how many things we found all around that were still blooming. We were also impressed by how much winter interest there was in the form of seed heads, spent flower stalks, and other plant parts left in place, as opposed to everything being chopped down to the ground as soon as fall arrives (which is often the case in our part of the world). We may not have been there in the warmest or sunniest time of year, but there was still plenty of natural beauty to capture our attention.

Bergius Botanic Garden

The first of the two gardens we visited was Bergius Botanic Garden (a.k.a. Bergianska trädgården) in Stockholm, Sweden. It is located near Stockholm University and the Swedish Museum of Natural History. It was founded in 1791 and moved to its current location in 1885. It was immediately obvious that the gardens were thoughtfully planned out, particularly the systematic beds in which the plants were organized according to their evolutionary relationship to each other. The extensive rock garden, which was a collection of small “mountains” with a series of paths winding throughout, was also impressive. Since we arrived just as the sun was beginning to set, we were happy to find that the Edvard Anderson Conservatory was open where we could explore a whole other world of plants, many more of which were flowering at the time.

Walking into Bergius Botanic Garden with the Edvard Anderson Conservatory in the distance.

Sierra poses with kale, collard, and Brussels sprout trees in the Vegetable Garden.

seed heads of velvetleaf (Abutilon theophrasti)

corky bark of cork-barked elm (Ulmus minor ‘Suberosa’)

pomelo (Citrus maxima) in the Edvard Anderson Conservatory

Camellia japonica ‘Roger Hall’ in the Edvard Anderson Conservatory

carrion-flower (Orbea variegata) in the Edvard Anderson Conservatory

Cape African-queen (Anisodontea capensis) in the Edvard Anderson Conservatory

Copenhgen Botanical Garden

The Copenhagen Botanical Garden (a.k.a. Botanisk have) is a 10 hectare garden that was founded in 1600 and moved to its current location in 1870. It is part of the University of Copenhagen and is located among a series of glasshouses built in 1874, a natural history museum, and a geological museum. Unfortunately, the glasshouses and museums were closed the day we visited, but we still enjoyed walking through the grounds and exploring the various gardens.

A large rock garden, similar to the one at Bergius, was a prominent feature. We learned from talking to a gardener working there that since Denmark is not known for its rich supply of large rocks, most of the rocks in the garden came from Norway. However, a section of the rock garden was built using fossilized coral found in Denmark that dates back to the time that the region was underwater.

Another great feature was the Nordic Beer Garden, a meticulously organized collection of plants used in beer recipes from the time of the Vikings to the Nordic brewers of today. Even though the majority of the plants in this garden were dormant, the interpretive signage and fastidious layout was memorable.

Walking into Copenhagen Botanical Garden with the Palm House in the distance.

lots of little pots of dormant bulbs

seed head of Chinese licorice (Glycyrrhiza echinata)

fruits of Chinese lantern (Physalis alkekengi)

alpine rose (Rhododendron ferrugineum)

Viburnum farreri ‘Nanum’

seed head of rose of Sharon (Hibiscus syriacus)

pods exposing the seeds of stinking iris (Iris foetidissima)

Eating Weeds: Dandelion Flowers

Mention weeds, and the first plant most of us think of is dandelion. It is essentially the poster child when it comes to weeds and one of the few weeds that entire books have been written about. Its notoriety partly comes from being so ubiquitous and recognizable, but it also comes from its utility. It has a long history of being used medicinally and culinarily, and, surprising to some I’m sure, is still grown agriculturally today.

Dandelion is an attractive and useful plant whose main offense is being so accomplished and proficient at staying alive, reproducing, and moving itself around. The principal thing it gets accused of is invading our lawns. With its brightly colored flowers on tall stalks and its globe of feathery seeds, it makes itself obvious, unlike other lawn invaders that tend to blend in more. Once it makes itself at home, it refuses to leave, adding to the frustration. Consider the vats of herbicide that have been applied to turf grass in an attempt to wipe out dandelions. The fact that they hang around, taunting those who care about that sort of thing, helps explain why they are so hated.

common dandelion (Taraxacum officinale)

As Ken Thompson writes in The Book of Weeds, dandelions are “too familiar to need describing,” and since there is already so much written about them, I don’t feel the need to write much myself. Below, instead, are a few excerpts from a handful of books that discuss them.

“It seems many of us possess a conscious will not to believe anything good about this remarkable harbinger of spring which, by its ubiquity and persistance, make it the most recognized and most hated of all ‘weeds.'” — The Dandelion Celebration by Peter Gail

“Dandelion heads consist entirely of overlapping ray florets. … Each floret has its own male and female organs, the (female) style surmounting the (male) stamens. Stamens are unnecessary, however, for the plant to produce seed; much, if not most dandelion seed reproduction occurs asexually (apomixis), without pollen fertilization or any genetic involvement of male cells. But insect pollination (each floret produces abundant nectar in its tubular base) and self-pollination, plus vegetative reproduction via sprouting of new plants from roots and root fragments, also occurs – so this plant has all reproductive fronts covered, surely an important reason for its wide abundance and distribution.” — The Book of Field and Roadside by John Eastman

“Wild violets are too limp and their flowers to insipidly small, too prone to damp, dark corners, as if lacking upright amour propre; in contrast, dandelions are too lush and healthy, their vigorous, indestructible roots, gaudy flowers, and too-plentiful seed heads all too easily spawned with their easygoing means of reproduction by parachute-like seeds, landing where they will, suggesting something of human sexual profligacy.” — Weeds by Nina Edwards

Charles Voysey “The Furrow” (© Victoria and Albert Museum, London

“Dandelions demonstrate evolution in action on suburban lawns. Over several seasons of mowing, the only dandelions that can flower are short-stemmed plants that duck the blade. Mowing thus becomes a selective factor, and in time most of the yard’s surviving dandelion flowers hug the ground.” — The Book of Field and Roadside by John Eastman

“When you stop seeing them as villains, many weeds can be considered as useful plants and certainly have been in the past. Dandelions produce fresh, green leaves nearly all year round. They make a nice addition to a salad, although most people find them too bitter to eat in any quantity. … Dandelion roots are edible too, and have been used in the past as a coffee substitute. If you can find some nice fat burdock roots to go with them, you could even make your own old-fashioned dandelion and burdock drink.” — The Alternative Kitchen Garden by Emma Cooper

“Early medieval Arabian physicians recognized the medicinal properties of dandelion, recorded in Egyptian tombs and described by Theophrastus. Its diuretic effects are mirrored in the common names of pissabed and the French pissenlit; it is recommended for the liver, kidneys, and gallbladder, and even for the treatment of diabetes. In India it is also a traditional remedy for snakebites and its milky sap is said to cure surface tumors and warts, and even unsightly moles and freckles.” — Weeds by Nina Edwards

I ate dandelion flowers blended up with eggs and cooked like scrambled eggs. Its a simple recipe that I adapted from instructions found in the The Dandelion Celebration by Peter Gail. The flowers taste more or less the way they smell. They have a bitterness to them that is akin to their leaves but isn’t nearly as strong. I have eaten dandelion leaves several times and I like them, so the bitterness doesn’t really bother me. If I were to make this again I would use a higher egg to dandelion flower ratio, because even though I enjoyed the flavor, it was a little strong.

Eating Weeds: Clovers

If you ever spent time hunting for four-leaf clovers in the lawn as a kid, in all likelihood you were seeking out the leaves of Trifolium repens or one of its close relatives. Commonly known as white clover, the seeds of T. repens once came standard in turfgrass seed mixes and was a welcome component of a healthy lawn thanks to its ability to fix atmospheric nitrogen and provide free fertilizer. But around the middle of the 20th century, when synthetic fertilizers and herbicides became all the rage, clover’s reputation shifted from acceptable to disreputable. Elizabeth Kolbert, in an article in The New Yorker about American lawns, recounts the introduction of the broadleaf herbicide 2,4-D: “Regrettably, 2,4-D killed not only dandelions but also plants that were beneficial to lawns, like nitrogen-fixing clover. To cover up this loss, any plant that the chemical eradicated was redefined as an enemy.”

white clover (Trifolium repens) in turf grass

This particular enemy originated in Europe but can now be found around the globe. It has been introduced both intentionally and accidentally. Commonly cultivated as a forage crop for livestock, its seeds can be found hitchhiking to new locations in hay and manure. Clover honey is highly favored, and so clover fields are maintained for honey production as well. Its usefulness, however, doesn’t protect it from being designated as a weed. In Weeds of North America, white clover is accused of being “a serious weed in lawns, waste areas, and abandoned fields.”

White clover is a low-growing, perennial plant that spreads vegetatively as well as by seed. It sends out horizontal shoots called stolons that form roots at various points along their length, creating a dense groundcover. Its compound leaves are made up of three, oval leaflets, and its flower heads are globe-shaped and composed of up to 100 white to (sometimes) pink florets. Rich in nectar, the flowers of white clover draw in throngs of bees which assist in pollination. Closely related and similar looking strawberry clover, Trifolium fragiferum, is distinguished by its pink flowers and its fuzzy, rounded seed heads that resemble strawberries or raspberries. Red clover, T. pratense, grows more upright and taller than white and strawberry clovers and has red to purple flowers.

leaves and seed heads of strawberry clover (Trifolium fragiferum)

Clovers are tough plants, tolerating heat, cold, drought, and trampling. Lawns deprived of water go brown fairly quickly, revealing green islands of interlopers, like clover, able to hang in there throughout dry spells. These days, many of us are reconsidering our need for a lawn. Lawns are water hogs that require a fair amount of inputs to keep them green and free of weeds, pests, and diseases. The excessive amounts of fertilizers and pesticides dumped on them from year to year is particularly troubling.

Along with our reconsideration of the lawn has come clover’s return to popularity, and turfgrass seed mixes featuring clover are making a comeback. To keep clover around, herbicde use must be curbed, and so lawns may become havens for weeds once more. Luckily, many of those weeds, including clover, are edible, so urban foragers need only to step out their front door to find ingredients for their next meal.

The leaves and flowers of clover can be eaten cooked or raw. Fresh, new leaves are better raw than older leaves. That being said, clover is not likely to be anyone’s favorite green. Green Deane refers to it as a “survival or famine food” adding that “only the blossoms are truly pleasant to human tastes,” while “the leaves are an acquired or tolerated taste.” In The Book of Field and Roadside, John Eastman remarks: “As humanly edible herbs, clovers do not rank as choice. Yet they are high in protein and vitamins and can be eaten as a salad or cooked greens and in flower head teas. Flower heads and leaves are much more easily digested after boiling.”

I tried strawberry clover leaves and flower heads in a soup made from a recipe found in the The Front Yard Forager by Melany Vorass Herrara. Around two cups of clover chopped, cooked, and blended with potatoes, scallions, and garlic in vegetable or chicken broth is a fine way to enjoy this plant. I don’t anticipate eating clover with great frequency, partly because it is included in a list of wild edible plants with toxic compounds in The North American Guide to Common Poisonous Plants and Mushrooms and also because I have to agree with the opinions of the authors quoted above – there are better tasting green things. Either way, it’s worth trying at least once.

clover soup

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