The Secrets of Spring Ephemerals in the Woods

“The wonder of the world, the beauty and the power, the shapes of things, their colours, lights and shades—these I saw. Look ye also while life lasts.” —Anonymous lines found on an old tombstone in Cumberland, England

“While life lasts.” This can be a very brief moment in time for a spring ephemeral. In that narrow window that exists between thawing ground and the leafing out of the tree canopy, spring ephemerals—those woodland wildflowers that emerge, then quickly go dormant—live their life.

White trout lilies (Erythronium albidum)
White trout lilies (Erythronium albidum)

If you want to see some of the spring woodland flowers in bloom, you often have to be there on the day. In the McDonald Woods at the Chicago Botanic Garden, sometimes all you find are petals scattered on the ground, and you realize you have to wait another year. This is particularly true of species like bloodroot (Sanguinaria canadensis), whose blossoms only last for a day before they drop. Additionally frustrating is that cloud cover can hamper catching the full glory of the blooming of some species. You may show up on a sunny morning only to have the blossoms close up before your eyes. Species like spring beauties (Claytonia virginica) will only open in the full sun and will close again if clouds appear. This response to sunlight may be the result of temperature or light. Some ephemerals might provide longer viewing opportunities, since they hold their flowers for a longer period of time, or have many more plants that flower on different days.

Bloodroot (Sanguinaria canadensis)
Bloodroot (Sanguinaria canadensis)
Spring beauty (Claytonia virginica)
Spring beauty (Claytonia virginica) by Kaldari, via Wikimedia Commons

Most of the spring ephemerals are perennial. They have underground organs—bulbs, corymbs, etc.—that store nutrients to be used for producing leaves and flowers in succeeding year. White trout lilies (Erythronium albidum) are a good example. The trout lilies, both white and yellow species, derive one of their common names from the mottled leaves that some think resemble the markings on a trout. (Other common names include adder’s tongue and dog-toothed violet—the second name is curious because these are plants in the lily family, having no relationship to violets.)

Trout lilies also spread by underground rhizomes that form clumps, often covering large patches in the woodland, the mottled leaves camouflaging their abundance, only to become dazzling drifts of white when the sun appears. If you have  time, you can come out to the woodland early in the morning and watch the white petals of the trout lilies curl back and expose their yellow anthers to the sun—and pollinators.

There are also a few annual spring ephemerals. False mermaid (Floerkea proserpinacoides) is a spring ephemeral annual. Unlike many of the other ephemerals, false mermaid is inconspicuous in that it is a small, ferny green plant with tiny greenish flowers. Portions of the nature trail in the McDonald Woods are surrounded with acres of this species in spring. Even in these large numbers, without close inspection, it is difficult to tell when they are in flower. This species is dependent on its flowers producing one to three large seeds to be able to reproduce itself after the plant turns yellow and dies.

Many of the spring ephemerals depend on native bees for their pollination. 

The trout lilies are visited by an oligolectic bee (Andrena erythronii). “Oligolectic” means this is a bee that has a narrow, specialized pollen preference, typically for the pollen of a single genus of plants. The species name of this bee, erythronii, refers to the genus of the trout lily, Erythronium. Another ephemeral with an oligolectic bee pollinator is the spring beauty. The bee that is a specialist of this ephemeral, with its attractive pink-striped flowers, is Andreana erigeniae

Squirrel corn (Dicentra canadensis)
Squirrel corn (Dicentra canadensis) by Fritzflohrreynolds (Own work) [CC BY-SA 3.0], via Wikimedia Commons

While these plants often have specialist pollinators associated with them, they usually have several different pollinators that can visit, including other native bees and many species of flies.

For ephemerals in the genus Dicentra, such as Dutchman’s breeches and squirrel corn (Dicentra canadensis), queen bumblebees are an important pollinator. These ephemerals have tightly closed flowers, requiring significant strength to enter the flower and access the pollen and nectar. The large queen bumblebees are among the few pollinators equipped to gain access. This is not only important for the plants, it is also important for the bumblebees. Many native bees colonies die off in fall, leaving the queens to overwinter and start the new colonies in spring. These large, fuzzy bees are able to manufacture enough physiological heat, by vibrating their wing muscles and restricting their blood flow in the thorax, to get themselves flying early in spring before it’s warm enough for many other pollinators to go foraging for resources to start the new colonies. The spring ephemerals provide this important resource.

Besides being important sources of nectar and pollen for native insects, the spring ephemerals also serve the purpose of saving soil and reducing water runoff during a time of year when few other plants are growing.

Trout lilies, for example, have very efficient photosynthetic abilities and take advantage of the high light levels available in the spring woodland. This strong photosynthetic response requires large quantities of water to maintain the process. Therefore, abundant populations of this species and other ephemerals absorb large quantities of water that would otherwise move off site, often carrying valuable nutrients and soil with it. This high demand for moisture also causes the ephemerals to have shorter flowering periods in times of drought. In your yard, you can encourage ephemerals to flower longer during dry conditions by providing a little extra water. There is also some thought that the rapidly decomposing foliage of these “short-lived” plants provides readily available nutrients for other plants that begin growing later in the season.

One other fascinating thing about spring ephemerals is that essentially all of them rely on ants to disperse their seeds. This relationship is referred to as myrmecochory—”myrmex” being the Greek word for ant.

Each seed of the spring ephemerals has a structure called an elaiosome attached to its surface that attracts ants. The elaiosome is rich in lipids and proteins. The ants take the seeds back to their nests and consume the elaiosome as food, after which they bring the seed to the surface and deposit it on their trash piles, where the seeds tend to germinate in a rich, organic seedbed.

I include another plant with elaiosomes in the list of spring ephemerals. This is parasol sedge (Carex umbellata). This grass-like, early-flowering sedge produces most of its seeds very close to the soil surface, where ants are more likely to find them. It is not uncommon to find ants nesting at the base of these plants. I often get questions from people who have planted ephemerals in their yard, but say they don’t see seedlings, while their neighbors are finding them on their property. It is more than likely that the neighbors have the ant colony that is harvesting the seed and sowing them at the neighbors’.

Parasol sedge (Carex umbellata)
Parasol sedge (Carex umbellata)

Given that the spring ephemerals are adapted to growing in a cool, moist environment and highly dependent on early spring pollinators, climate change is likely to cause stress in the system. Early warming and possibly drought conditions in spring may disrupt pollinator interactions or shorten flowering periods, making seed production more difficult, or reducing the amount of time ephemerals have for storing nutrients for future flowering. 

False rue anemone (Isopyrum biternatum)
False rue anemone (Isopyrum biternatum)

With spring on the horizon, you should make plans to visit the McDonald Woods to view the diversity of colorful spring wildflowers. For those of you taking pictures, pay attention to weather forecasts, and be mindful of the potential to damage other vegetation while attempting to get the perfect shot.


©2018 Chicago Botanic Garden and my.chicagobotanic.org

The Warm Weather and Your Garden

The late February weather in Chicago has been a glorious time to be outside and work in the garden. But the unseasonably warm weather has also raised questions about the long-term effect on plants and what garden tasks are appropriate.

It is best to hold off on doing any detailed clean up of garden beds as the mulch and leaves in the beds will provide some protection to any early growing perennials when the weather eventually turns cold again. Raking leaves off the lawn and cutting back perennials are all fine to do now providing your garden soil is not too wet.

Snowdrops are blooming at the Garden.

Early flowering bulbs like snowdrops that are in flower here at the Chicago Botanic Garden are very tolerant of the cold. Daffodil and tulip foliage is coming up; these might end up being damaged by a spell of cold weather, but this should not affect the spring flowers. You do not need to take any special maintenance steps to protect these plants.

If you have some perennials that are growing in a warm area of the garden with more pronounced growth, they might benefit from a light layer of mulch. For the most part, though, there is nothing special for most gardeners to do in their perennial beds.

This is great weather to prune but proceed with care. Spring flowering shrubs like viburnums, lilacs, and forsythia set their flower buds last year so pruning done at this time of year will remove flower buds and reduce the number of spring flowers. You can still prune—just be aware of the flower buds as you are pruning. Forsythia flowers along the stems while viburnums will have a flower bud at the ends of the stem.

The dormant season, and in particular late winter, is the best time of year to complete rejuvenation pruning, which is the aggressive pruning of overgrown shrubs to bring them back into scale with the garden. Shrubs like hydrangea (except oak leaf hydrangea), potentilla, and spirea that flower on new wood respond well to pruning now too. For instance, I cut my Annabelle hydrangea back to the ground each spring.

Any plants installed last summer or fall should have been mulched when they were planted. If they were not, then mulch them now to help mitigate the temperature swings in the soil and prevent frost heaving of any plants in spring. The freezing and thawing of the soil can push recently installed small plants such as 1-gallon perennials or ground covers that were grown in containers out of the soil as the weather transitions to spring.

If we receive a good covering of snow, the snow itself will not harm plants unless it builds up on them and breaks branches. It is a good idea to brush plants off during a storm if you observe them getting weighted down. Later snowstorms are more likely to come in wet and heavy. Leave the plants alone if the snow has frozen on them to avoid breaking branches during the removal process.

Enjoy the warm weather and the early blooms, both at the Chicago Botanic Garden and in your own backyard.

Summer Comes to the Dwarf Conifer Garden

Early summer in the Dwarf Conifer Garden is all about the new growth. Everything is bursting forth with fresh new growth in vivid shades of green, chartreuse, yellow…and blue!  

PHOTO: Dwarf Conifer Garden in spring.
Layers of color draw you into hidden paths throughout the Dwarf Conifer Garden.

Many of the trees feature entirely unexpected colors. For most of the year, Spring Ghost blue spruce (Picea pungens ‘Spring Ghost’) looks like your average Colorado spruce. From early spring through midsummer, however, the tips of every branch shine with the palest yellow—nearly white—new growth. Likewise, Taylor’s Sunburst lodgepole pine (Pinus contorta ‘Taylor’s Sunburst’) is a handsome green tree for most of the year—until spring, when radiant yellow new growth bursts forth, bringing a welcome dose of sunshine to the garden.

PHOTO: Picea pungens 'Spring Ghost'.
Picea pungens ‘Spring Ghost’
PHOTO: Pinus contorta 'Taylor's Sunburst'.
Pinus contorta ‘Taylor’s Sunburst’
PHOTO: Pinus cembra 'Blue Mound'.
Pinus cembra ‘Blue Mound’

New needles aren’t the only attraction this time of year. Many conifers have cones that start out in surprising shades! Blue Mound Swiss stone pine (Pinus cembra ‘Blue Mound’) would be a beautiful plant in its own right, with its long, soft, blue-green needles. But when you throw in dusky purple cones, you get a plant that is truly a gem. As the cones age, they’ll slowly turn into the more typical brown of a ripe cone, but right now, they’re as pretty as any flower.

Red can be a difficult color to find in conifers, but Acrocona spruce (Picea abies ‘Acrocona’) has cones that start out a vivid ruby red and slowly fade to a soft tan. The cones start out upward-facing, but slowly begin to droop as they age.

PHOTO: Picea abies 'Acrocona'.
Picea abies ‘Acrocona’ has cones that start ruby red, and slowly fade to tan.
PHOTO: Abies koreana 'Silver Show'.
Abies koreana ‘Silver Show’

Another unique plant is Silver Show dwarf Korean fir (Abies koreana ‘Silver Show’). Unlike other conifers, the firs (Abies sp.) have cones that always face upward. ‘Silver Show’ is beautiful any time of the year, but its purple upward-facing cones really make it special in spring. The cones start out small and green, but as you can see in this picture, they begin to turn purple as they grow until you’re left with dozens of dark purple cones set against perfectly tiered, silvery green foliage. There really is nothing else like it in the Garden.

PHOTO: Male cones on Pinus leucodermis.
Male cones on Pinus leucodermis

On most conifers, it’s the female cones that are most showy and most often noticed, but on Bosnian pine (Pinus leucodermis), it’s the male (pollen-bearing) cones that steal the show. Arranged in groups at the end of every branch, they light up the tree like little Christmas lights. Even on a gloomy day, the bright orangey-tan color stands out against some of the deepest green needles in the garden.

All of these colors are a seasonal show that is best appreciated before things start to heat up for the summer, so now is your best time to come see them!


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Ready, Set, Spring!

Sure, it snowed just three days into spring—it’s Chicago! This week we’re set to hit the magic temperature, 45 degrees Fahrenheit, and here’s what it will trigger in your garden.

ILLUSTRATION: How trees set buds in spring.


©2015 Chicago Botanic Garden and my.chicagobotanic.org

Toad Serenade at the Cove

Have you heard the sounds coming from nearby lakes, ponds, and puddles this month? The American toads are singing!

PHOTO: female toad looking directly at the camera
This female American toad may be listening for the enchanting song from a handsome male toad.

Every spring, the toads emerge from hibernation in wooded areas and hop to the nearest standing water to breed. The sound you hear comes from the males, who are singing to attract a mate. You’ll hear the sound of hundreds of toads at the Kleinman Family Cove for the next week or so, maybe longer.

The toads will pair up and lay a string of eggs in shallow water where it is warmest and rich in food for their offspring. After laying eggs, the adults will return to the woods or shady gardens to look for food, leaving their babies to fend for themselves.

PHOTO: the toad pair are together in the water with a string of black eggs she has laid around the algae.
The black lines of dots in the water are strings of eggs that were laid by the toad on the right.

The black embryo inside each egg will grow into tiny tadpoles and hatch in about a week. They will grow and develop into half-inch toadlets over the next few weeks. Then they will leave the water and join their parents in the shady gardens and woods. With any luck, some of them will survive the next two years, developing to full maturity, and return to the Cove to breed.

This is the only time of year to hear the toads singing, so visit the Cove this month. If you visit over the next four weeks, maybe you’ll see some little black tadpoles swimming in the water.

Please resist the urge to collect them to take home. You won’t be able to provide enough of the right kind of food for a growing tadpole or toadlet, and they will die. Watch them grow up successfully in their natural habitat at the Cove throughout the month of May and early June instead!


©2013 Chicago Botanic Garden and my.chicagobotanic.org