Growing ephemerals in wildlife gardens

 

Ephemerals are only active above ground for a short part of the year. By summer, they have disappeared. Including ephemerals in your garden demands patience, greater thoughtfulness about garden design and exacting care. Why do we love them so? Well, the flowers are absolutely beautiful. Planting ephemerals increases diversity and they provide an early source of pollen and nectar for spring pollinators. They often have a special relationship with ants, which are relied upon to disperse the seed. To encourage ants to do this, there is a fatty structure called an elaiosome on the outer part of the seed that ants can eat. Ephemerals may also play an ecological role in nutrient recycling.

 

1) List of ephemerals

2) How to garden with ephemerals

3) Biology of ephemerals

	Dicentra canadensis in flower. The nectary is located at the top of the flower on the inside. A bumblebee with a long tongue can reach this and effect pollination. At the same time, the bumblebee is getting a much-needed source of energy.

 

In the deserts of the south-west, ephemerals are annuals that complete their life-cycle in matter of months. They remain dormant as seeds until there is excess rain and then they all grow and bloom at the same time. Seeing a desert superbloom should be on every gardener's bucket list. The ephemerals of the North-East and the great lakes are the exact opposite. They live for decades and you may have to wait more than ten years just to see their first bloom. They slowly build up a store of sugars and nutrients in a perennial organ.

Types of perennial organs:

Bulbs

Think of an onion and its many layers. Each layer is a modified leaf that can store starch. In the middle of a bulb is a group of cells that can reproduce quickly. This called the apical meristem and it is located at the tip of the bulb, which is where you see the growth begin.

Corms

These form as a swelling at the base of the stem. Corms look like bulbs but they do not have the layers. They have lateral areas of growth and you will see shoots growing out of the sides of a corm instead of just at the tip. Corms should be planted close to the soil surface so that the tip is just visible.

Rhizomes

These are swollen stems that grow horizontally across the soil. They have nodes in various places from which a new shoot can grow.

Tubers

These are located in the root systems of ephemeral plants. Unlike rhizomes which are spread out, tubers are more concentrated stores of starch and require less energy to maintain. Ephemerals rely more on tubers when they have really short growing seasons and when they have a lower tendency to spread out vegetatively.

 

	Cardamine concatenata in flower.

 

A list of popular ephemerals in gardens.

Name	Notes
Allium tricoccum or Allium burdickii	The only allium to be considered an ephemeral, but during its dormancy period, it flowers and goes to seed. The perennial organ is a bulb.
Anemone quinquefolia	A groundcover that does well in moist soil. It will spread through its perennial organ, a rhizome.
Camassia scilloides	A wild hyacinth that does well in moist rich and well drained soil. It requires part sun or full sun and can be difficult to grow. It takes a few years to get going but the flowers are worth waiting for. The perennial organ is a bulb and it produces a moderate amount of nectar to attract pollinators.
Wild hyacinths can be tricky to grow.
Cardamine concatenata.	Cutleaf toothwort is a good choice for regular garden soil or even a sandy loam.
Claytonia virginica	Produces a fair amount of nectar. The perennial organ is a tuber. Claytonia caroliniana is a similar species, but it is not an ephemeral.
Corydalis flavula	A short-lived perennial that uses tubers as the perennial organ. It can tolerate more disturbed and drier soils.
Corydalis flavula is very rare in Ontario and difficult to obtain.
Dentaria laciniata	This is the old name for Cardamine concatenata
Dicentra canadensis	Good for moist soils. Used by queen bumblebees. The perennial organ is a tuber. Dicentra are less likely to form associations with mycorrhiza and have longer root systems than other ephemerals.
Dicentra cucullaria	Good for moist soils. Needs richer soil than D. canadensis so it is harder to grow. The perennial organ is a tuber.
Claytonia virginica
Erythronium sp.	Also called fawn lilies. The perennial organ is a bulb.
Mertensia virginica	Prefers rich moist soils, but it is more flexible than other species. It is one of the easiest perennials to grow and will make the garden look enchanting. The perennial organ is a rhizome. This is a nectar producing plant. It attracts queen bumblebees and possibly hummingbirds.
Trillium sp.	Trillium erectum is an ephemeral but all the Trillium species have a shorter growing season. Most species have rhizomes, but T. cernuum uses tubers as a perennial organ. All Trillium produce seeds with elaiosomes.

	A beginner plant for those new to ephemerals. The large pendulous flowerheads of Virginia bluebells makes this plant a truly wonderful addition to a wildlife garden. The location of the flowers at the top of the shoot makes them very accessible to pollinators.

A number of other species were not included as ephemerals because they have foliage that grows in late July or August and therefore do not face the same level of adversity. If you want to know more about these plants see spring flowers.

2) Gardening tips

Ephemerals are likely to be more expensive than your average native plant because more care is required to raise these plants. They are trickier to transplant so do not assume that you will have 100 % success with these plants. Given their expense and the difficulty that you might have replacing them, consider protecting ephemerals from rabbits and other animals that might disturb them during the epigeous phase.

Ephemerals are not total shade plants. They need high light in the spring. Lower amounts of light results in more leaf development but less energy is available to form flowers and seeds. Ephemerals are not plants that you can put on the north side of a wall, but you can plant them under a deciduous tree in an area where sunlight can reach the ground.

The plants you buy from a nursery are young and it is important that you give them every opportunity to sequester carbon and nutrients for the following year. Be careful when putting young plants in the ground as the stalk connecting the root section to the leaf section can be incredibly thin. If you break this connection, the plant may never grow back. You can move the block of soil directly from the pot to the ground ensuring that the foliage is at ground level (this is the easiest method) or you can very carefully prise the soil away from the plant. When doing this, you are looking for the perennial storage organ, which might be the size of a bean and the connecting stalk. Be careful about the depth of planting. The foliage should be at ground level and the stalk connecting with the perennial organ should be reasonably straight. If the stalk is bunched up, dig a deeper hole. Carefully fill in the hole with a small amount of soil at a time.

Plant them as soon as you get them because they need to acquire nutrients and many ephemerals need to form connections with mycorrhizal fungi to aid nutrient uptake. Place a label or a marker behind each of your ephemerals so that you know where to look for them in the following year and it is really important that you avoid disturbing these areas. Since ephemerals struggle every year to get enough nutrients and stored sugar, physically interrupting their growth can result in the plants needing several years to recover lost nutrients.

In order to get enough nutrients, place ephemerals in nutrient rich soil. Ephemerals carry out most nutrient uptake during the period of high light in the spring. By adding decaying leaves to your beds in the fall, you can enrich the soil for the plants in the spring. The leaves will also aid mycorrhizal fungi that form mutualistic relationships with ephemeral plants.

Reduce the stress on your ephemeral plants during their epigeous phase by keeping the soil moist at this time. A dry soil will make it difficult for these plants to obtain enough of both nutrients and water. During the dormancy period, water is not really an issue. In the fall, some moisture in the soil will be needed as these plants become more active underground.

Do not clean up the leaves even when you think that photosynthesis may have stopped. Yes, it can look a bit messy, but ephemerals cannot acquire all the nutrients they need through assimilation from the soil. Up to 40% of the nutrients for next year's growth comes from nutrient recycling as the above-ground vegetative material senesces. If you want your ephemeral blooms to look their best, you need to max out the nutrient supply.

Interplant your perennials with plants that emerge and flower later in the year. This is possible because the plants will be uptaking nutrients at different times of the year and competition will be reduced.

 

3) Biology of ephemerals

Typically, ephemerals of the north east and the great lakes are found in woodlands. While the trees have yet to leaf out, dappled sunlight reaches the forest floor. Ephemerals take advantage of a brief period during which intense photosynthesis is possible and frost damage is minimal in order to grow leaves, flowers and seeds. These plants are well adapted to carrying out photosynthesis at low temperatures. The terms "canopy closure" or "flushing date" refer to the point at which trees have leafed out and therefore reduced the photosynthetic activity for all understory plants.

Growing above ground and photosynthesising for less than 2 months in springtime creates some unique challenges. These plants have to max out the acquisition of carbon and nutrients in the perennial storage organ while at the same time ensuring that there is enough energy and nutrients to develop flowers and set seed. It is interesting to note that plants in the tundra also have a short growing season and have evolved similar strategies to adapt to their environment.

	You may need to protect Dutchman's breeches from rabbits.

 

Ephemeral plants employ some of the following strategies to survive in difficult conditions:

They develop shoots and flower buds underground in winter so that the plant is ready to go as soon as temperatures are high enough.

Since the foliage has a high protein content, ephemerals can photosynthesise well and increase carbon storage at lower temperatures than other plants. The proteins required for photosynthesis are produced early on to allow photosynthesis to start quickly. The foliage also has a high nutrient concentration that supports growth. Many ephemerals form symbiotic relationships with mycorrhizal fungi that may help the plants obtain nutrients even during the period of dormancy.

Some species have flowers on scapes, which are stalks devoted mainly to flowering. This allows the flowerhead to start growing above ground immediately and at the same time as the leaves. Flower and seed production can be aided by translocating sugars and nutrients from the leaves. The plants can also save energy by producing little or no nectar.

The flowers are in sync with early pollinators and because there are so few other flowers available, competition for pollinators is reduced; therefore, several ephemerals produce little or no nectar. Some of the seeds produced have elaiosomes that are fat rich structures on the seed surface. Ants move the seeds back to the nest so that they can eat the elaiosome and in return the seed has been moved away from the original location.

Ephemeral plants efficiently reclaim nutrients from the above-ground vegetation as it undergoes senescence.

 

The annual cycle

Dormancy occurs in nearly all ephemerals and it is initiated by an increase in shade due to canopy closure or elevated temperatures. I grow yellow trout lily in areas of the garden that experience little change in light intensity due to canopy closure, yet these plants still go into dormancy. Lapointe (2001) suggests that leaf senescence could also be triggered by sink limitation. The perennial organ has to absorb sugars and store it as starch. If the perennial organ has reached the maximum level of starch storage, sugars cannot be transferred from the leaves. This is a sink limitation. Instead, the concentration of sugars builds up in the leaves and this could trigger senescence.

With the exception of Allium tricoccum, there is no root or shoot growth during dormancy; however, there are some cellular changes within the buds that have formed in preparation for next year's growth. Some of the cells specialise so that distinct tissues form. In Allium tricoccum, a scape grows during its "dormancy" period that bears flowers and then goes on to form a seed head. The roots also keep growing. There are several possible advantages to flowering later. The plant itself can concentrate its energy reserves just on producing flowers and setting seed during a period in which there is no risk of frost damage and less risk of herbivory.

	The flowerhead of Allium tricoccum in July

 

The hypogeous phase covers the underground growth of ephemeral plants during the fall and winter months. In preparation for above ground growth in the spring, new roots develop and some shoot development occurs as well. The perennial organ supplies the nutrients and carbohydrates needed for this development. If the perennial organ cannot accumulate enough resources during the spring, then it could affect development during the hypogeous phase and therefore the growth of the plant in the following spring. During the winter, the shoots and flower buds have developed enough that they are ready to emerge after the snow melts.

The epigeous phase covers the period of above ground growth. The shoots emerge and grow quickly. The plants soon reach maximum photosynthetic activity to take advantage of the radiant energy reaching the forest floor and it is during this phase that maximum nutrient absorption occurs as well. The cells in the perennial organ have to undergo cell division, which is followed by a period of cell expansion, in order to increase its ability to store starch and nutrients. Consequently, storage cells are larger than the cells in other parts of the plant. Inside the cell, starches are stored in large plastids called amyloplasts. More of these plastids can be accommodated in fully expanded cells. An extended period of cooler spring temperatures favours the ability of the perennial organ to maximise carbon and nutrient storage.

	The flowerheads in Dicentra are growing on scapes and can emerge at the same time as the leaves. There is an advantage in having flowerheads with their own basal stalk.

 

 

Some non-ephemerals emerge early so there is no rule that ephemerals are the first plants to start growing above ground. Even in non-ephemeral understory plants, most of the photosynthetic activity occurs before canopy closure. Dicentra canadensis and Mertensia virginica are amongst the first ephemerals to emerge and flower in the garden. These flowers are important sources of nectar for bumblebee queens that have emerged from their winter resting site and are actively seeking nectar to fuel their needs as they search for a nesting site to start the first brood of workers.

Mertensia virginica has purple leaves when it emerges due to production of anthocyanins. It is noticeable that rabbits tend not to browse on this plant, but they love eating the flowers of Dicentra canadensis. The flowers are not on a scape, but you will notice that the most developed leaves are at the top of the shoot and they protect the flower bud, which has already formed below ground using stored energy reserves in the rhizome. As a result, less energy is needed mature the flowers. While hormones cause the shoot to grow rapidly, the flower bud develops at a good pace and they are ready to bloom while the shoot is still growing.

	The purple leaves of Mertensia virginica may give some protection from herbivores

Assuming that the plant is mature enough to produce flowers, the epigeous phase continues with flower production and seed development. The seeds may be developing as the leaves are senescing. The plant can use the sugars from the leaves to ensure the maturation of the seeds. As the leaves senesce, nutrients are efficiently reclaimed and reused for future growth, which is essential for the plant's survival.

Many papers were perused to write this page, but I would like to credit one review paper in particular for a lot of the information: Lapointe, L., 2001. How phenology influences physiology in deciduous forest spring ephemerals. PHYSIOLOGIA PLANTARUM, 113, pp. 151–157.