Podcast Review: Botanical Mystery Tour

My interest is piqued any time plants are featured or plugged in popular culture. Hence my ongoing series of posts, Botany in Popular Culture, featuring Futurama, Saga of the Swamp Thing, etc. Plants just don’t get enough airtime, so it must be celebrated when they do. Which is why I was excited to learn about Chicago Botanic Garden‘s new podcast, Botanical Mystery Tour, in which the plants referenced in pop culture take center stage.

The hosts, as they state in each episode’s introduction, “dive into the botany hidden in our favorite stories.” To help with the discussion, they bring in experts that work at Chicago Botanic Garden to explore the science (and fiction) behind the plant references. In addition to discussing pop culture and the related science, the guests share details about the work they do at the Garden and some of the research they are working on.

In the first episode, Jasmine and Erica ask Paul CaraDonna about the drone bees featured in an episode of Black Mirror. Since many bee species are in decline, will we have to resort to employing robot bees to pollinate plants that rely on bee-assisted pollination? A great discussion about native bees and colony collapse disorder ensues.

(But maybe the idea of autonomous drone insects isn’t too far-fetched…)

In episode two, the hosts ask why humans are so obsessed with corpse flowers. Thousands of people flock to botanical gardens to see these humongous, stinky flowers on the rare occasions they are in bloom, so what is so appealing about Amorphophallus titanum? Patti Vitt joins the discussion to share details about this fascinating plant.

A corpse flower in bloom is a brief and uncommon occurrence, reminiscent of the Sumatran Century Flower in The Simpsons and the 40 Year Orchid in Dennis the Menace.

 

The third episode features the sarlaccs of Star Wars. It turns out, sarlaccs are carnivorous plants. This discovery spawns an interesting discussion with horticulturist Tom Weaver about what defines a carnivorous plant and the various ways that different carnivorous plant species capture and kill their prey.

The fourth (and latest) episode is an exploration into the magical world of mushrooms. In Alice in Wonderland, Alice encounters a large, hookah-smoking caterpillar sitting atop a giant mushroom. Are there mushrooms big enough that a person could actually sit on them like Alice does? Greg Mueller joins the podcast to address this and many other mycology-based questions. The conversation includes a great discussion about why a botanical garden (whose main focus is plants) would be interested in fungus.

The discussions in this podcast are fun and enlightening. The hosts shine the spotlight on often overlooked characters in popular media, and with the help of their guests, lead captivating conversations about the science related to these characters. With only a handful of episodes available so far, it will be easy to get caught up. And then you, like me, will find yourself anxiously looking forward to embarking on another Botanical Mystery Tour.

———————

Is there a plant-themed podcast or podcast episode you would like to recommend? Please do so in the comment section below.

Advertisements

Seed Oddities: Vivipary

Seeds house and protect infant plants. When released from their parent plant, they commence a journey that, if successful, will bring them to a suitable location where they can take up residence (upon germination) and carry out a life similar to that of their parents. Their seed coats (and often – in the case of angiosperms – the fruits they were born in) help direct them and protect them in this journey. Physical and chemical factors inhibit them from germinating prematurely – a phenomenon known as dormancy. Agents of dispersal and mechanisms of dormancy allow seeds to travel through time and space — promises of new plants yet to be realized.

There is rarely a need for a seed to germinate immediately upon reaching maturity. In many cases, such as in temperate climates or in times of drought or low light, germinating too soon could be detrimental. The most vulnerable time in a plant’s life comes when it is a young seedling. Thus, finding the right time and space to get a good start is imperative.

The fruits (and accompanying seeds) of doubleclaw (Proboscidea parviflora) are well equipped for long distance dispersal. (via wikimedia commons)

In rare instances, dispersal via seeds offers little advantage; instead, dispersal of live seedlings or propagules is preferable. For this select group of plants, vivipary is part of the reproductive strategy. In vivipary, seeds lack dormancy. Rather than waiting to be dispersed before germinating, viviparous seeds germinate inside of fruits that are still attached to their parent plants.

Occasionally, seeds are observed germinating inside tomatoes, citrus, squash, and other fruits; however, these fruits are usually overripe and often detached from the plant. In these instances, what is referred to as “vivipary” is not a genetic predisposition or part of the reproductive strategy. It’s just happenstance – a fun anomaly. The type of vivipary discussed in this post is actually quite rare, occurring in only a handful of species and prevalent in a select number of environments.

There are three main types of vivipary: true vivipary, cryptovivipary, and pseudovivipary. In true vivipary, a seed germinates inside the fruit and pushes through the fruit wall before the fruit is released. In cryptovivipary, a seed germinates inside the fruit but remains inside until after the fruit drops or splits open. Pseudovivipary is the production of bulbils or plantlets in the flower head. It does not involve seeds and is, instead, a form of asexual reproduction that will be discussed in a future post.

True vivipary is commonly seen among plant communities located in shallow, marine habitats in tropical or subtropical regions, such as mangroves or seagrasses. The term mangrove is used generally to describe a community of plants found in coastal areas growing in saline or brackish water. It also refers more specifically to the small trees and shrubs found in such environments. While not all mangrove species are viviparous, many of them are.

Seedlings of viviparous mangrove species emerge from the fruit and drop from the plant into the salty water below. From there they have the potential to float long or short distances before taking root. They may land in the soil upright, but often, as the tide recedes, they find themselves lying horizontally on the soil. Luckily, they have the remarkable ability to take root and quickly stand themselves up. Doing this allows young plants to keep their “heads” above water as the tides return. It also helps protect the shoot tips from herbivory.

Viviparous seedlings emerging from the fruits of red mangrove (Rhizophora mangle) via wikimedia commons

Another example of vivipary is found in the epiphytic cactus (and close relative of tan hua), Epiphyllum phyllanthus. Commonly known as climbing cactus, this species was studied by researchers in Brazil who harvested fruits at various stages to observe the development of the viviparous seedlings. They then planted the seedlings on three different substrates to evaluate their survival and establishment.

Epiphyllum phyllanthus is cryptoviviparous, so the germinated seeds don’t leave the fruit until after it splits open. In a sense, the mother plant is caring for her offspring before sending them out into the world. The researchers see this as “a form of parental care with subsequent conspecific [belonging to the same species] nursing.” Since the plant is epiphytic – meaning that it grows on the surface of another plant rather than in the soil – local dispersal is important, since there is no guarantee that seeds or propagules dispersed away from the host plant will find another suitable site. That being said, the researchers believe that “vivipary involves adaptation to local dispersal,” since “the greater the dispersal distance is, the higher the risk and the lower the probability of optimal dispersion.”

Epiphyllum phyllanthus via Useful Tropical Plants

While some viviparous seedlings of mangroves can travel long distances from their parent plant and don’t always root into the ground immediately, they maintain their advantage over seeds because they can root in quickly upon reaching a suitable site and lift themselves up above rising tide waters. As the authors of the Epiphyllum study put it, vivipary is “a reproductive advantage that, in addition to allowing propagules to root and grow almost immediately, favors quick establishment whenever seedlings land on suitable substrates.”

There is still much to learn about this unusual and rare botanical feature. The research that does exist is relatively scant, so it will be interesting to see what more we can discover. For now, check out the following resources:

Also, check out this You Tube video of :

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!

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

———————

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.

The Dragon of Yankee Fork: Spalding Viaduct

This is a guest post by Martha Dalke Hindman. It is an excerpt from her upcoming book, The Dragon of Yankee Fork. This is the final of three posts. See also: Devil’s Washbasins and Grave Markers.

———————

Spalding Viaduct, from the Old Mission site over the Railroad tracks
Built in 1924, steel rods, concrete construction, supporting arches and pillars.
570 feet long, 20 feet wide, a Link in U.S. Highway 95 connecting Idaho, North to South.
Today, a Chain Link Fence and Steel Gates surround the structure.

Black Locust trees, cascading white or lavender flowers
Compound leaves, dark brown seed pods.
Shade and shelter for family picnics and softball games
Beside the Spalding Viaduct, the Nez Perce Tribal Cemetery

black locust (Robinia pseudoacacia)

Travel with my Dad was always an adventure. However, the Spalding Viaduct on U.S. Highway 95, was the scariest stretch of concrete highway, we ever encountered.

Dad slowed to a stop as we approached the Spalding Viaduct. A semi tractor-trailer rig was traveling north and in the center of the viaduct, leaving no room for any other vehicles. I watched as the driver carefully drove his rig down the narrow span. The driver slowed, saluted his “thanks” to us, and continued his journey. Normal traffic, backed up at either end of the viaduct, continued to their destinations. Dad and I were on our way to Boise – Idaho’s Capitol City.

Dad continued the story about how the Spalding Viaduct on U.S. Highway 95 connects the State of Idaho, North to South and South to North.

“The Spalding Viaduct is the vital link for travelers to stay within the geographical boundaries of the State of Idaho. Otherwise, to reach Boise from Lewiston, travel west and south on U. S. Highway 12 to Walla Walla, Washington, cross the Columbia River south to Umatilla, Oregon Highway 82. Outside Umatilla, connect with U.S. Highway 84 east through Southeast Oregon, across the Snake River at Ontario, Oregon and into Boise. The only other way to reach Boise from our home in Moscow, is to travel south on U.S. Highway 95 to Lewiston, turn east on U.S. Highway 12 into Hamilton, Montana. From Hamilton, south on U.S. Highway 93 through the magnificent Bitterroot Valley, to the Montana, Idaho border. U.S. Highway 15 takes you to Idaho Falls and U.S. Highway 86 into Boise. Coming from our home in Moscow, travel time to Boise would be two days. That is why the Spalding Viaduct is so vital to North-South and South-North traffic.”

“Dad, do we change time zones before we reach Boise??”

“Yes, Martha Lee. Time zones change from Pacific Standard Time, to Mountain Standard Time when we cross the Salmon River Bridge at Riggins. Because we are traveling south, we lose one hour. Watch for a roadside park with a picnic table. Mother packed a lunch full of sandwiches, goodies and a thermos full of ice cold water. We should arrive in Boise about 7 pm. Mountain Standard Time. In the meantime, enjoy the scenery.”

“Dad, there is JUST the place for our picnic, under the shade of the black locust trees.”

We parked our car at the picnic area next to the Spalding Viaduct. The black locust trees in bloom, a gentle breeze brought “fishy” smells from the Clearwater River, the water still high and rapid from the spring rains. The log drive was finished, only a few pieces of debris floated by.

Several families were finishing their noon meal, as we sat down at the long wooden table and unpacked our lunch. Mother had prepared peanut butter and honey sandwiches, potato salad, liverwurst slices, cheddar cheese, carrots and strawberries from our garden, chocolate chip cookies, and a large Coleman thermos of cold water. What a feast!

The afternoon sun was warm, the breeze calm, just the recipe for a game of softball. Dad batted first. A gentle swing to left field. Home Run!!

My turn to bat! I swung, missing the first ball. The second pitch, I hit, but it flew straight into the Clearwater River. The strong current carried my softball downstream. I could not catch it. End of Game!

I cried. Dad put his strong arms around my sagging shoulders. “It’s OK, Martha Lee. I’ll see to it that you have another softball. We will never know how far your old ball will travel. It may get stuck in debris along the river banks, or it may end up in the Pacific Ocean, riding the ocean currents to the shores of the Hawaiian Islands, or maybe even into Shanghai Harbor, China!”

Several days later, Dad came home with a package under his arm. With a twinkle in his eye, Dad gave me the box. I opened the shiny, square box. Inside was a new softball ready to be played with and loved just as much as the old one.

Thanks, Dad.

Additional Information:

The Spalding Viaduct is falling apart, literally. Large pieces of the concrete columns become loose and fall to the ground. This once vital link on U.S. Highway 95 is closed with steel gates and a chain link fence. Moss grows where semi trucks carrying goods and produce South to North and North to South, passenger cars and buses, traveling South to Boise and North to Canada, watched out for each other on the narrow roadway.

Modern day travelers and truck traffic continues to travel North-South and South-North on U.S. Highway 95, over a new bridge (built in 1962) across the Clearwater River to the East of the Spalding Viaduct. A new stretch of highway was constructed from the river bridge, over the railroad tracks, up the hill, and onto the Camas Prairie. U.S. Highway 95 continues south to Grangeville, Riggins, and ends at Middleton, Idaho. U.S. Highway 44 connects with U.S. Highway 84 into Boise.

Updates were made to the current bridge in 2014. Click here for more information.

———————

Poetry, personal stories, images, journal entries, recipes for Springerle, Cinnamon Rolls, Fried Cakes, “a little bit of science thrown in for good measure,” print and online resources, all define “The Dragon of Yankee Fork,” an Idaho Alphabet from A to Z. It all began on a long piece of cream colored shelf paper! (Visit the Go Fund Me page to learn more about the project and contribute to its creation.)

Martha Dalke Hindman’s outdoor classroom was the travel adventures she shared with her father around the State of Idaho. From dusty roads, fishing expeditions, and a keen sense of observation, learning about Idaho’s heritage gave Ms. Hindman her voice in poetry and personal short stories. She may be reached at martha20022 [at] gmail [dot] com.

Introducing Herbology Hunt

This is a guest post by Jane Wilson.

———————

Many people are “plant blind”. They walk through areas of fantastic wildlife or just down their street without noticing what grows there. Even plants growing in the gutter have an interesting backstory.

The term “Plant Blindness” was first put forth by Wandersee and Schlusser in 1998. Without an appreciation of plants in the ecosystem, people will be less likely to support plant research and conservation.

Herbology Hunt was born out of a love of plants and wild places and a determination to get kids outdoors and really looking at their environment. One of the founders started Wildflower Hour on Twitter – a place for people to share photos of wildflowers found in Britain and Ireland – and from this was stemmed a children’s version, which became Herbology Hunt. The Herbology Hunt team put together spotter sheets for each month of the year. Each sheet includes five plants that can be found throughout the month. They were made available as a free download, so schools and individuals can print them for use on a plant hunt.

By the end of 2018, we had created a year’s worth of spotter sheets. We are now looking to promote their use throughout Great Britain. Eventually we want to reward children who find 50 of the plants with a free T-shirt, and we will be looking for sponsors to support this. We have been supported by the Botanical Society of Britain and Ireland and the Wild Flower Society who have made the monthly spotter sheets available. They can be downloaded here or here.

Herbology Hunt Spotter Sheet for January

The Wild Flower Society has a great offer for Juniors interested in plants – it costs £3 to join and you get a diary to record your finds.

Going outdoors and noticing wildlife has been shown in some scientific studies to improve cardio-vascular health and mental health. A herbology hunt must surely be a good thing to do with children to help them get into a better lifestyle that will benefit their future health. We hope that many families and schools will use our spotter sheets as a way to help children become more passionate about the environment and enjoy the benefits of being outdoors.

Check out the Wildflower Hour website for more information about Herbology Hunt, along with instructions on how to get involved in #wildflowerhour, plus links to social media accounts and the Wild Flower (Half) Hour podcast.

———————

Also: Check out Jane Wilson’s website – Practical Science Teaching – for more botany-themed educational activities.

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

———————

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.

———————

Do you find these posts valuable? Consider giving us a high five in the form of money to help us continue to tell the story of plants.

Donate