Eating Weeds: Chicory

Over the course of human history, plant species once esteemed or considered useful have been recategorized into something less desirable. For one reason or another, plants fall out of favor or wear out their welcome, and, in come cases, are found to be downright obnoxious, ultimately losing their place in our yards and gardens. The particularly troublesome ones are branded as weeds, and put on our “do not plant” lists. These plants are not only unfavored, they’re despised. But being distinguished as a weed doesn’t necessary negate a plant’s usefulness. It’s likely that the plant still has some redeeming characteristics. We’ve just chosen instead to pay more attention its less redeeming ones.

Chicory is a good example of a plant like this. At one point in time, Cichorium intybus had a more prominent place in our gardens, right alongside dandelions in fact. European colonizers first introduced chicory to North America in the late 1700’s. Its leaves were harvested for use as a salad green and its roots were used to make a coffee additive or substitute. Before that, cultivation of chicory for these and other purposes had been going on across Europe for thousands of years, and it still goes on today to a certain extent. Along with other chicory varieties, a red-leafed form known as radicchio and a close cousin known as endive (Chicorium endivia) are grown as specialty crops, occassionally finding their way into our fanciest of salads.

Radicchio di Chioggia (Cichorium intybus var. foliosum) is a cultivated variety of chicory. (via wikimedia commons)

Chicory’s tough, adaptable nature and proclivity to escape cultivation have helped it become widespread, making itself at home in natural areas as well as urban and rural settings. Its perennial life history helps make it a fixture in the landscape. It sends down a long, sturdy taproot and settles in for the long haul. It tolerates dry, compacted soils with poor fertility and doesn’t shy away from roadside soils frequently scoured with salts. It’s as though it was designed to be a city weed.

Unlike many other perennial weeds, chicory doesn’t spread vegetatively. It starts its life as a seed, blown in from a nearby plant. After sprouting, it forms a dandelion-esque rosette of leaves during its first year. Wiry, branched stems rise up from the rosette in following years, reaching heights of anywhere from about a foot to 5 or 6 feet. When broken, leaves, stems, and roots ooze a milky sap. Abundant flowers form along the gangly stems. Like other plants in the aster family, each flower head is composed of multiple flowers. Chicory flower heads are all ray flowers, lacking the disc flowers found in the center of other plants in this family. The petals are a brilliant blue – sometimes pink or white. Individual flowers last less than a day and are largely pollinated by bees. The fruits lack the large pappus found on dandelions and other close relatives, but the seeds are still dispersed readily with the help of wind, animals, and human activity.

chicory (Cichorium intybus) via wikimedia commons

The most commonly consumed portions of chicory are its leaves and roots. Its flowers and flower buds are also edible. Young leaves and blanched leaves are favored because they are the least bitter. Excluding the leaves from light by burying or covering them up keeps them pale and reduces their bitter flavor. This is standard practice in the commercial production of certain chicory varieties. The taproots of chicory are dried, roasted, and ground for use as a coffee substitute. They are also harvested commercially for use as a natural sweetener due to their high concentration of inulin.

my puny chicory root

I harvested a single puny chicory root in order to make tea. On my bike ride to work there is a small, sad patch of chicory growing in the shade of large trees along the bike path. I was only able to pull one plant up by the roots. The others snapped off at the base. So, I took my tiny root, dried and roasted it in the oven, and ground it up in a coffee grinder. I followed instructions for roasting found on this website, but there are many other sources out there. I had just enough to make one small cup of tea, which reminded me of dandelion root teas I have had. Sierra found it to be very bitter, and I agreed but still enjoyed it. I figure that wild plants, especially those growing in stressful conditions like mine was, are likely to be more bitter and strong tasting compared to coddled, cultivated ones found in a garden.

roasted chicory root

roasted and ground chicory root

When I find a larger patch of feral chicory, I hope to try one of several recipes included in Luigi Ballerini’s book, A Feast of Weeds, as well as other recipes out there. I’ll be sure to let you know how it goes.

Are you curious to know how chicory became such a successful weed in North America? Check out this report in Ecology and Evolution to learn about the genetic explanation behind chicory’s success.

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Seed Dispersal by Way of Tree Climbing Goats

Goats are surprisingly good climbers. Given the opportunity, they’ll climb just about anything, including each other. So what’s stopping them from climbing a tree, especially if there is something up there they can eat? And so they do. Tree climbing goats are such a fascinating sight, they even have their own calendar. But the story doesn’t end there. The goats find food in the trees, entertaining humans as they go; meanwhile, the trees have a reliable partner in the goats, who inadvertently help disperse the tree’s seeds.

In general, goats don’t need to climb trees to find food. Goats aren’t known to be picky eaters, and there is usually plenty for them to eat at ground level. However, in arid climates where food can become limited, ascending trees to eat foliage and fruits is a matter of survival. This is the case in southwestern Morocco, where goats can be found in the tops of argan trees every autumn gorging on the fruits of this desert tree.

goats in Argania spinosa via wikimedia commons

Argan (Argania spinosa) is a relatively short tree with a sprawling canopy and thorny branches. It is the only species in its genus and is endemic to parts of Morocco and neighboring Algeria. The tree is economically important to the area due to the oil-rich seeds found within its bitter fruits. Argan oil has a variety of culinary uses and is also used medicinally and in cosmetics. To get to the oil, goats are often employed in harvesting the fruits. The goats retrieve the fruits from the tops of the trees and consume their fleshy outer layer. The hard, seed-containing pits are expelled, collected, and cracked open to get to the seeds.

This is where a team of researchers from Europe come in. There has been some confusion as to how the pits are expelled, with some reports claiming that they pass through the goats digestive track and are deposited in their manure. This is a common way for the seeds of many other plant species to be dispersed, and is carried out not only by goats and other ruminants, but also by a wide variety of mammals, as well as birds and even reptiles. However, considering the average size of the pits (22 mm long x 15 mm wide), the researchers thought this to be unlikely.

fruits of Argania spinosa via wikimedia commons

Others reported that the seeds were spat out in the goats’ cud while they ruminated. Goats, like other ruminants, have stomachs composed of multiple compartments, the first of which being the rumen. Partially digested food, known as cud, is sent back into the mouth from the rumen for further chewing and may be spat out or swallowed again. Goats are known to ruminate in the same location that they defecate, which results in confusion as to when and how certain seeds, like those of the argan tree, are deposited.

By feeding various fruits to a group of goats, the researchers were able to test the hypothesis that seeds could be regurgitated and spat from the cud and that this is a viable method of seed dispersal. The researchers reported that larger seeds were more commonly spat out than smaller seeds, but that “almost any seed could be ejected during, mastication, spat from the cud, digested, or defecated.” The viability of spat out seeds was tested, and over 70% of them were found to be viable.

pits and seeds of Argania spinosa via wikimedia commons

This discovery suggests that seed dispersal via spitting by ruminants could be a common occurrence – possibly far more common than previously considered. The researchers postulate that studies that have only considered seeds dispersed in manure “may have underestimated an important fraction of the total number of dispersed seeds” and that the seeds spat from the cud likely represent different species from those commonly dispersed in dung. In addition, the seeds of some species don’t survive the digestive tract of ruminants, so “spitting from the cud may represent their only, or at least their main, dispersal mechanism.”

This study surrounding the argan trees was followed up by the same group of researchers with a literature review that was published last month. The review looked into all available studies that mentioned seed dispersal via regurgitation by ruminants. While they considered over 1000 papers, only 40 published studies were found to be relevant for the review. From these studies, they determined that the seeds of 48 plant species (representing 21 different families) are dispersed by being spat from a ruminant’s cud, and that most of these plant species are trees and shrubs whose fruits contain large seeds. Also of note is that ruminants across the globe are doing this – representatives from 18 different genera were mentioned in the studies.

ruminating goat via wikimedia commons

The researchers conclude that this is a “neglected” mechanism of seed dispersal. It’s difficult to observe, and in many cases it hasn’t even been considered. Like so many other animals, ruminants can disperse seeds in a variety of ways. Seeds can attach to their fur and be transported wherever they go. They can pass through their digestive track and end up in their dung, potentially far from where they were first consumed. And, as presented here, they can be spat out during rumination. Investigations involving all of these mechanisms and the different plant species involved will allow us to see, in a much clearer way, the role that ruminants play in the dispersal of seeds.

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

The Flight of the Dandelion

The common dandelion (Taraxacum officinale) comes with a collection of traits that make it a very successful weed. Nearly everything about it screams success, from its asexually produced seeds to its ability to resprout from a root fragment. Evolution has been kind to this plant, and up until the recent chemical warfare we’ve subjected it to, humans have treated it pretty well too (both intentionally and unintentionally).

One feature that has served the dandelion particularly well is its wind-dispersed seeds. Dandelions have a highly-evolved pappus – a parachute-like bristle of hairs attached to its fruit by a thin stalk. The slightest breath or puff of wind will send this apparatus flying. Once airborne, a dandelion’s seed can travel up to a kilometer or more away from its mother plant, thereby expanding its territory with ease.

Such a low-growing plant achieving this kind of distance is impressive. Even more impressive is that it manages to do this with a pappus that is 90% empty space. Would you leap from a plane with only 10% of a parachute?

Dandelion flight was investigated by researchers at the University of Edinburgh, who used a wind tunnel along with long-exposure photography and high-speed imaging to observe the floating pappus. Their research was presented in a letter published in an issue of Nature in October 2018. Upon close examination, they observed a stable air bubble floating above the pappus as it flew. This ring-shaped air bubble – or vortex – which is unattached to the pappus is known as a separated vortex ring. While this type of vortex ring had been considered theoretically, this marked the first time one had been observed in nature.

Seeing this type of air bubble associated with the dandelion’s pappus intrigued the researchers. About a 100 filaments make up the parachute portion of the pappus. They are arranged around the stalk, leaving heaps of blank space in between. The air bubble observed was not what was expected for such a porous object. However, the researchers found that the filaments were interacting with each other in flight, reducing the porosity of the pappus. In their words, “Neighboring filaments interact strongly with one another because of the thick boundary layer around each filament, which causes a considerable reduction in air flow through the pappus.”

The pappus acts as a circular disk even though it is not one, and its limited porosity allows just enough air movement through the filaments that it maintains this unique vortex. “This suggests,” the researchers write, “that evolution has tuned the pappus porosity to eliminate vortex shedding as the seed flies.” Fine-tuned porosity and the resultant unattached air bubble stabilizes the floating fruit “into an equilibrium orientation that minimizes [its] terminal velocity, allowing [it] to make maximal use of updrafts.” The result is stable, long distance flight.

Wind-dispersed seeds come in two main forms: winged and plumed. Winged seeds are common in trees and large shrubs. They benefit from the height of the tree which allows them to attain stable flight. While such seeds have the ability to travel long distances, their success is limited on shorter plants. In this case, plumed seeds, like those of the dandelion, are the way to go. As the researchers demonstrated, successful flight can be achieved by bristles in place of wings. The tiny seeds of dandelions seen floating by on a summer breeze are not tumbling through the air haphazardly; rather, they are flying steadily, on their way to spoil the dreams of a perfect lawn.

Further Reading (and Watching):

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 its 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 eating, 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.

Tiny Plants: Idahoa

This is a post I wrote three years ago as a guest writer for a blog called Closet Botanist. That blog has since dissolved, hence the re-post.

This year, we returned to the location in the Boise Foothills where I encountered the plant that inspired this post. I found what might be seedlings of the tiny plant. If that’s the case, the phenology is a bit delayed compared to three years ago. I’ll check again in a week or so. Until then, meet Idahoa.

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I have taken a real liking to tiny plants. So many of the plants we regularly interact with are relatively big. Large trees loom above us. Tall shrubs greet us at eye level. Flowering perennials come up around our knees or higher. But how often do we get down low and observe the plants that hug the ground or that reach just a few centimeters above it? Turf grass is ubiquitous and groundcovers are common, but among such low growing plants (or plants kept low), even more diminutive species lurk.

It was a hunt for a tiny plant that sent me down a certain trail in the Boise Foothills earlier this spring. Listening to a talk by a local botanist at an Idaho Native Plant Society meeting, I learned about Idahoa scapigera. A genus named after Idaho!? I was immediately intrigued. Polecat Gulch was the place to see it, so off I went.

Commonly known as oldstem idahoa, flatpod, or Scapose scalepod, Idahoa scapigera is the only species in its genus. It is an annual plant in the mustard family, which means it is related to other small, annual mustard species like Draba verna. It is native to far western North America and is distributed from British Columbia down to California and east into Montana. It occurs in a variety of habitat types found in meadows, mountains, and foothills.

Idahoa scapigera is truly tiny. Before it flowers, it forms a basal rosette of leaves that max out at about 3 centimeters long. Next it sends up several skinny flower stalks that reach maybe 10 centimeters high (some are much shorter). One single flower is born atop each stalk. Its petite petals are white and are cupped by red to purple sepals. Its fruit is a flat round or oblong disk held vertically as though it is ready to give neighboring fruits a high five. Happening upon a patch of these plants in fruit is a real joy.

Which brings me to my hunt. It was the morning of March 20th (the first day of Spring) when I headed down the Polecat Gulch trail in search of Idahoa, among other things. The trail forms a loop around the gulch and is about 6 miles long with options for shortening the loop by taking trails that cut through the middle. I have yet to make it all the way around. Stopping every 10 yards to look at plants, insects, and other things makes for slow hiking.

I was about a half mile – 1 hour or more – into the hike when Idahoa entered my view. A group of them were growing on the upslope side of the trail, greeting me just below waist level. Many of them had already finished flowering and had fresh green fruits topping their thin stalks. At this location they are a late winter/early spring ephemeral. I made a mental note of the site and decided to return when the fruits had matured. Next year, I will head out earlier in hopes of catching more of them in flower.

On the way to Idahoa, I noted numerous other small, green things growing in the sandy soil. It turns out there are countless other tiny plants to see and explore. It got me thinking about all the small things that go unnoticed right underneath our feet or outside of our view. I resolved to move slower and get down lower to observe the wonders I’ve been overlooking all this time.

Further Reading:

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 :