Violets Are Blue…

She bathed with roses red, and violets blue,
And all the sweetest flowers, that in the forest grew.

Sir Edmund Spenser, 1590

Celebrated in song and verse for centuries, violets have been revered for their delicate beauty, their culinary and medicinal value, their sweet scent, and their happy association with spring. Depending on the culture and time, violets have been symbols of many virtues, including modesty, purity, faithfulness, everlasting love, and remembrance. With over 400 species distributed around the Northern Hemisphere, violets have been known, appreciated, and used by humans all over the world and throughout history.

Only in recent times have violets fallen into disrepute — as an enemy of the perfect lawn. Weed-killers have been employed widely to get rid of this “delicate and fair” little bloom. But at what cost? Let’s reconsider.

The Common Blue Violet, Viola sororia

The Common Blue Violet, native to forests and meadows of the Eastern US, is Viola sororia. The word sororia means “sisterly,” apparently because our native Violet bears a close family resemblance to the hundreds of other species of Viola distributed around the globe – a vast sorority!

The Viola genus also includes the large variety of annuals known in horticulture as “pansies,” but African violets are in an entirely different genus and unrelated. Numerous other species of Viola are native to the US in varying flower and leaf colors, and are suited to a variety of habitats. Horticulturists have developed cultivars of Viola sororia in pure white, speckled, and even grayish forms that are available for sale. But even in the wild, natural color variations are common among Viola sororia, so you may see blue and mostly-white flowers growing together.

Blue-and-white flowers occur naturally

Both the flowers and leaves of the Common Blue Violet are edible – and tasty! The leaves may be eaten raw in salads or cooked like spinach, and they are loaded with vitamins A and C. The flowers have a delicate flavor and are frequently used to garnish salads, or candied as a charming decoration for sweets. It’s easy to find directions on-line for making your own candied violets, and all you need is an egg white and sugar. Just be sure to harvest your violets from a spot that has NOT been treated with herbicide or pesticide!

Candied Violets are pretty and delicious

Violets have been used medicinally in many cultures. They are said to have anti-oxidant and anti-inflammatory properties and to be useful in a tea for treating coughs and colds. Poultices made from Violets also have been used to treat skin conditions like insect bites, dry skin, and eczema.

Like most native plants, the Common Blue Violet’s greatest value is to nature. Violets are the host plant for some of our most spectacular native butterflies – Fritillaries. Just like monarchs, whose caterpillars only feed on milkweed, all 20 species of Fritillaries must lay their eggs where their caterpillars can find Violet leaves. The caterpillars usually stay close to the ground, hiding under the leaves and feeding on them at night. The adult butterflies will visit many different nectar flowers and are always a thrill to see.

Great Spangled Fritillary butterfly
Photo: Marcie O’Connor,
Variegated Fritillary butterfly
Fritillary caterpillar feeding on Violet
Photo: Marcie O’Connor,

Violets are also an essential source of nectar to many early-emerging native bees. At least one species of American bee specializes in Violet pollen, meaning that is the only thing the bee can eat and feed its young. Andrena violae is a small bee common in the Eastern US that emerges from its winter hibernation in April and May and immediately begins hunting for Violets, which bloom at just the right time. The bee pollinates Violets so they can produce seed, keeping future populations of Violets available to feed Fritillaries — a great example of the inter-connection between native plants and multiple insects.

The native habitat of Viola sororia is moist woods and along streams, but it can adapt to sunny conditions with enough water, which explains why Violets do so well in fertilized and irrigated lawns. In the garden, in rich soil and partial shade, Violets make a lovely and durable groundcover. The heart-shaped leaves look tidy all summer long, and individual plants can live up to 10 years.

Violets make a pretty garden groundcover

Violets spread easily by seed, which is why they are so often considered “weedy.” In addition to producing seed from pollinated flowers, Violets utilize cleistogamy, a process of self-fertilization that guarantees survival even if unpredictable weather conditions in early spring do not allow for sufficient pollinator visits. Cleistogamous flowers appear in late summer, never opening for insect pollination, yet still producing fertile seeds. The seeds mature in capsules that literally explode, throwing seeds up to several yards away from the parent plant. Seed dispersal is further helped by ants that collect the seeds for their rich coating of protein and fat. The ants discard the seeds after consuming the coating, effectively planting them at even greater distances from the parent.

The medieval ideal of lawn in the Unicorn Tapestry

For most of our history, people considered a “flowery mead” to be the idyllic lawn, a beautiful and romantic place for children and lovers to frolic in the merry month of May. So, consider leaving the “modest and delicate” blossoms of violets blooming this spring. The bees and butterflies will thank you!

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A Perennial Star

It won’t be long now…the show is about to start! 

Each spring, excitement builds as Eastern Bluestar (Amsonia tabernaemontana) breaks ground and gets ready for its performance, which happens in three acts! Amsonia is a 3-season performer. From May through November, this native plant is a star.

Eastern Bluestar emerging in May

The overture starts in mid-spring when shiny green leaves emerge wrapped around deep blue flower buds. The buds ride along as the leafy stalks rise to a height of 30 to 40 inches. Soon, the real show begins as the pale blue stars that give the plant its common name open, attracting a huge variety of pollinators.

The flowers rise with the growing stalks
 Pale blue stars cover the plant by late May

The second act lasts all summer long – four full months! Amsonia is a clump-forming perennial that functions almost like a shrub. In time, the plant expands slowly from the base, but does not spread easily either by rhizomes or seed. The glossy foliage looks fresh all summer, reaching about 3 feet tall and almost as wide, and mixes well in a garden border, or even in a meadow planting. The stems may be cut back a bit after flowering to keep the plant’s compact form, or allowed to arch out in a looser shape.

Amsonia tabernaemontana at the New York Botanical Garden paired with Zizia aurea for a dazzling native combo
 Amsonia in the foreground with meadow plants in mid-summer

In Act Three, Amsonia turns bright yellow, and the fall color lasts for weeks! It looks great combined with evergreens and fall berries, or mixed with contrasting foliage colors. The plant goes dormant and dies back to the ground in winter after 7 months of extraordinary performance.

In November, Amsonia’s brilliant yellow contrasts with the purple foliage of Ninebark (Physocarpus opulifolius) at the Nature Center

Native to moist woodland edges, and along streams and ponds from New York to Florida and west to Texas and Illinois, Eastern Bluestar is happy in Zones 3 through 9. Though its natural habitats are moist areas with well-drained soil, it is quite drought tolerant once it is established, and is reported to tolerate clay as well. It prefers full sun in the northern part of its range, but appreciates some afternoon shade in warmer regions. 

Young plants may take a few seasons to get established, but Amsonia is a long-lived perennial. After a few years, the base of the plant becomes quite woody and difficult to divide, but left alone, it comes back year after year for a decade or more. And Amsonia is pest resistant – it has white latex sap that deer and other critters avoid. Gardeners with latex allergies may also wish to avoid it by wearing gloves. 

It’s surprising that Eastern Bluestar isn’t better known among today’s gardeners since even its name dates back to Colonial times. Amsonia was named for a physician and amateur botanist, John Amson, who lived in Williamsburg, Virginia and once had a very famous patient. In 1758, George Washington was worried that he had contracted “consumption” (tuberculosis) during the French and Indian War. Fearing the worst, he visited Dr. Amson for advice. The good doctor reassured General Washington that he had nothing more than a common cold and was not going to die. To honor the esteemed Dr. Amson, the botanist John Clayton named the perennial flower “Amsonia” shortly thereafter.

If you go shopping for Amsonia tabernaemontana, you are likely to run into a few other Amsonias, and there can be some confusion here. A variety called Amsonia tabernaemontana var. salicifolia is native to the southeastern U.S. and has slightly narrower leaves than the northern species. It is often sold in nurseries in the Northeast, and is difficult to distinguish unless they are viewed side-by-side. There is no particular reason to avoid salicifolia unless you are in the Northeast and trying to plant strictly local native species.

Amsonia ‘Blue Ice’ with taller Eastern Bluestar in the background

A more perplexing issue is presented by Amsonia ‘Blue Ice,’ which is being widely sold and is becoming increasingly popular. A few years ago, a commercial grower with a greenhouse full of Amsonia tabernaemontana noticed some plants in the crowd with slightly larger and darker blue flowers and foliage more compact than the species. Horticulturists first classed ‘Blue Ice’ as a “selection,” a naturally-occurring variation with desirable characteristics that is then cultivated for sale by stem cuttings. Further study, however, has suggested that ‘Blue Ice’ is of “uncertain parentage,” which sounds a bit scandalous and could mean that ‘Blue Ice’ is a hybrid or an accidental introduction or something else altogether. At present, although the genetic mystery rules out the plant for purists, it really is a lovely garden perennial. ‘Blue Ice’ stays under 2 feet tall, which is great in smaller gardens.

Amsonia hubrichtii

There is another popular species of Amsonia called Amsonia hubrichtii or Threadleaf Bluestar, which is native only to Arkansas and Oklahoma. Although it is a fine garden plant, and is regularly sold outside its native range, you will maximize ecological benefits in your own area by planting the species that is native there. 

For most of the Eastern US, and much of the Southcentral US, Amsonia tabernaemontana, our own Eastern Bluestar, is the true perennial star. Let the show begin!

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Before the Bulbs

Is it spring yet?

For many gardeners, the earliest signs of spring are snowdrops, crocuses, and daffodils. But if you know where to look, you can find blooming flowers — and the little critters who need them – even before those bulbs come to life. One of the earliest bloomers in the Northern half of the US also happens to be one of our most interesting and valuable native shrubs: Salix discolor, or the amazing Pussy Willow!

In February, Pussy Willows are already producing the adorable, fuzzy flowers that give them their common name. This type of flower has no petals or fragrance, and is known as a “catkin” from the Dutch word “katteken,” which means kitten. Just as soft to the touch as they look, the silvery catkins are popular in spring flower arrangements and delight children of all ages.

 Pussy Willows start blooming in February
The soft hairs on catkins protect the inner flower parts from cold and snow

Over the next month, the catkins will gradually open revealing numerous string-like filaments. Pussy willow shrubs are dioecious, meaning the shrub holds either male or female flowers. On the male plants, the filaments hold quantities of pollen that give the catkins a bright yellow appearance. The female flowers look more like spiny caterpillars than kittens, so for ornamental purposes, the male shrubs are preferred.

By mid-April, the catkins have opened and leaves begin to emerge

Pussy Willows typically are large, multi-stemmed shrubs or small trees, topping out between 15 and 25 feet. Unlike most trees, however, they can benefit from being severely pruned, or “coppiced,” to keep them shorter. Cutting back the branches after blooming will generate multiple slender new stems, increasing the fullness of the shrub and the number of catkins within easy reach in the following season. 

Humans have used the flexible young branches of willows for basket-weaving, arrows, rustic fencing, and many other purposes for hundreds of years. One of the most important traditional uses of willow bark was medicinal. Willow bark tea contains salicin, a pain-killer and fever reducer, now synthetically produced as aspirin.

Pussy Willow’s natural form is a large, multi-trunked shrub, but it can easily be pruned as a hedge or privacy screen

By far the most important use of Pussy Willow in our gardens, however, is to support native pollinators and other insects. As one of the very earliest plants to bloom, Pussy Willow provides nectar and pollen for early-emerging native bees. In fact, the Andrina family of native bees are willow “specialists” – they must have willow pollen to feed their young. The nectar of willow catkins also supports many other insects in early spring when food is especially scarce.

 A tiny ant finds what it needs on Pussy Willow

All summer long, the leaves of Pussy Willow feed the caterpillars of more than 450 species of moths and butterflies — second only to oak trees in providing caterpillars for baby birds! Willow is a host plant for a huge number of our most spectacular butterflies: Viceroy, Red-spotted Purple, Mourning Cloak, and various hairstreaks, fritillaries, and dusky-wings.

Mourning Cloaks are just one of hundreds of butterfly species that depend on willows

In addition to Pussy Willows, there are at least 90 species of willows native to the US, and 20 or more native to the Northeast. Unfortunately, there are also many non-native species sold in the nursery trade, including the well-known weeping willow (Salix babylonica), that do not provide the same value to our native birds and insects. Be sure to check the scientific name before you add a willow to your landscape.  Pussy Willow (Salix discolor), Black Willow (Salix nigra), Shining Willow (Salix lucida), and Silky Willow (Salix sericea) are all good native shrubs, but Pussy Willow is likely the easiest to find.

Pussy Willow is a great choice for sunny wet areas, including rain gardens. It is an ideal solution for a soggy lawn area where rainwater tends to collect. All willows have extensive root systems that seek out water, so they should not be planted near a septic system, but they are perfect near a stream or pond or anywhere you want to stabilize a slope eroded by stormwater.

Deer will browse Pussy Willow, but because the shrub actually benefits from winter pruning, the nibbling is unlikely to harm the plant. Pussy Willows grow fast and are very resilient. In fact, many people propagate them simply by cutting off a dormant stem in winter and sticking it in the ground, or even a glass of water, until roots appear. Hardy in Zones 2 through 7, the only thing Pussy Willow does not tolerate well is shade. You’ll need at least a half day of sun, and plenty of water until the roots are established. 

Pussy Willow is an all-around winner: easy to grow, interesting and attractive, incredibly valuable for the ecology, and a real problem-solver for a troublesome spot in the landscape.

So, where will you put it?


Back to School

Many of us grown-ups, upon learning of the complex relationships between native plants and insects, wonder “why am I hearing about this for the first time?” or “did I miss this in school?”  No worries! You are not alone. This subject only recently has become part of the basic biology curriculum.

At the Greenburgh Nature Center, we want people of all ages to understand this vital relationship. So, let’s start at the beginning — with some visual aids!

“Native” plants are the species that evolved in a particular place without human intervention. In the US, that means the trees, shrubs, grasses, and perennials that were here before European settlers arrived. Native plants are important largely because of their relationship with native insects. 

The majority of insects eat plants. Most other animals, including humans, also eat plants, or they eat other animals that eat plants. As the main food supply for most living things, plants would soon be wiped off the face of the Earth if they did not develop strategies to protect themselves from all of these plant-eaters!

Most insects eat plants
Illustration: Masha Role

Over the millennia, plants evolved defenses to protect themselves from plant eaters. You may recognize a few of these if you’ve eaten a very hot chili pepper or had a bad reaction to touching poison ivy. Insects (the largest category of plant eaters) face similar problems.

Plants have developed many defenses to hungry insects
Illustration: Masha Role
Toxic leaf chemicals, sticky sap, spines and thorns, stinging hairs, fibrous tissue, bloom time, and even height are evolutionary plant defenses to insect predators
Illustration: Masha Role

To survive, insects had to evolve methods of overcoming plant defenses. But the enormous variety and complexity of defenses in the plant world limited insects to overcoming only the specific defenses of a limited number of plant families. As a result, about 90% of all plant-eating insects are “specialists,” meaning they are able to eat only a few closely-related species of plants. Those plants became the “host” plants for the insect species adapted to overcoming their specific defenses.

Specialist insects eat their host plants, but cannot eat other plants. The host plants can survive and reproduce because they are eaten only by the insects specialized to them.
Illustration: Masha Role

The best-known example of this insect/host relationship is the monarch butterfly and milkweed. Milkweed has sticky sap loaded with toxins that repel most insects. The monarch caterpillar evolved the ability to tolerate those toxins, but has no ability to overcome the defenses of other plants. Monarch caterpillars cannot eat the leaves of plants outside of the milkweed family.

Monarch caterpillar on milkweed
Monarch butterflies can drink the nectar of many flowers, but must lay their eggs on milkweed

The situation is the same for most plant-eating insects. These evolutionary plant/insect relationships developed over very long stretches of time, thousands of years. So, most insects can eat only those plants that evolved with them in the same place and over the same long period of time. That is why insects native to North America cannot eat plants that have been brought in, or “introduced,” by human settlers from other continents.

As you look around your neighborhood, you will no doubt see many plants introduced from other continents: Norway maples, Korean dogwoods, Japanese maples, Norway spruces, Japanese barberry, English ivy, Chinese feather grass, and many more. These non-native plants have evolutionary relationships with insects on other continents, but most North American insects cannot eat them. Many of these plants are marketed as “pest-free” for exactly that reason. Insects here avoid them, and many gardeners like that! 

But “pest-free” plants come at a terrible cost: nearly all (96%) of our native terrestrial birds need insects to feed their young. Well-documented and shocking declines in insect and bird populations over the past 50 years tell us we are facing a crisis. Without native plants, we lose insect populations. Without insect populations, we lose birds. We also lose all of the other animals that feed on insects, as well as butterflies, fireflies, and specialist bees that pollinate food crops and most of our flowering plants. More broadly, without native plants, biodiversity itself is threatened and our ecosystems become unstable.

Fortunately, this is one crisis we can solve in our own yards. By choosing native plants, and planting a lot more of them, we can actually bring insect species back from the brink of extinction!

The Atala butterfly

A wonderful example of this is the story of the beautiful Atala butterfly, native to parts of Florida. The Atala was believed to be extinct from 1939 until the 1960’s when a small population was discovered on an undeveloped island off the Florida coast. Then, in the 1980’s, horticulturists discovered and began growing a lovely small plant called the Coontie palm (Zamia floridana or integrifolia). Coontie was once common in Florida, but it was overharvested in the wild by early settlers for its starchy root. By the 1930’s, the plant had largely disappeared from the Florida landscape. Beginning in the late 1980’s, the re-discovered Coontie became popular with homeowners and was planted in gardens and along walkways in many Florida suburbs. And suddenly, the Atala butterfly re-appeared!

Coontie is the only plant Atala caterpillars can eat

It turns out that Coontie is the host plant for the Atala butterfly! As Coontie became popular in suburban yards, the Atala butterfly rebounded. Today, this beautiful butterfly is common enough that some misguided homeowners look for pesticides to control the Atala caterpillars eating their Coontie plants!

So, hopefully, we adults are now on common ground with today’s kids. We understand that native plants are a key element in the health of our planet. If we continue to use “pest-free” non-native plants, we will continue to see our favorite back-yard birds disappear, along with monarchs, other butterflies, and the rest of the natural food web. Or, we can do a simple good thing for nature: fill our yards with native plants and provide the food so critical for life.


If You Can Do Just One Thing…

Conservationists, ecologists, and this blog repeatedly urge gardeners to use more native plants. Native plants are essential to a healthy ecosystem because they are the first link in the food chain. Insects native to a particular region generally cannot eat plants from other regions, and insects are the primary food source for birds and many other animals. We know that insect and bird populations are declining rapidly, so we ask homeowners, residents, and property managers to replace lawn, which has no ecological value, with abundant plantings of native trees, shrubs, grasses, and perennials. 

But not everyone can do that. Gardening is not everyone’s hobby and, for many people, taking care of a lawn and a few shrubs is really all they can manage. So, what if you want to help save songbirds, butterflies, and fireflies, but transforming an entire landscape to native plants is not an option? 

In a recent interview, Dr. Douglas Tallamy, research scientist and best-selling author of several books about the interaction between native plants and insects, was asked whether there are any simple things that anyone with a yard can do to benefit insects and birds. He immediately responded, “Plant an oak tree.”

Autumn foliage on a Pin Oak (Quercus palustris)
A young White Oak (Quercus alba) in summer

Planting a native oak tree — or saving one — may be the single most valuable thing you can do to support nature. Oak trees are “keystone” plants, which means they are essential to the survival of many other species. Without them, there would be a cascade of species extinctions.

 Baby birds need insects

The importance of oaks to our native birds is perhaps the most dramatic example. Virtually all songbirds need insects to feed their young. Baby birds cannot eat seeds or berries. They must have insects, especially caterpillars. Caterpillars, the larvae of moths and butterflies, are soft, easily digested, and loaded with the nutrition baby birds need. Dr. Tallamy’s research has shown that a pair of Black-capped Chickadees needs 7,000 to 9,000 caterpillars to raise a single clutch of 3 baby chicks to maturity. Chickadees are very small birds and, if there is enough food, they can raise 2 clutches of babies in a season — that’s a lot of caterpillars! All of our other backyard birds have the same needs. Adult birds spend all day finding and transporting thousands of caterpillars to their nests. And where is the best place to find all those caterpillars? On the leaves of native oak trees!

 Black-capped Chickadee with caterpillar
Photo: Dr. Douglas Tallamy

Oak trees are caterpillar factories. Over 500 species of moths and butterflies lay their eggs and hatch their caterpillars on native oak trees. By comparison, not one single species of North American moth or butterfly caterpillar can mature on the leaves of a Norway maple! In fact, none of the popular non-native trees typically planted in suburban yards help birds feed their babies. Japanese maples, crape myrtles, Korean dogwoods, Norway spruces, Callery pears, and Kwansan cherries are essentially “barren” – they do not support caterpillar populations or other insects of value to birds. 

Caterpillars of Hairstreak butterflies must hatch on oak leaves

Planting a native oak tree, or saving one from destruction, is an easy way to support biodiversity. There are over 90 species of oaks native to the US, and many of them are widely available, hardy, easy to care for, and very long-lived. In the Northeast, white oak, red oak, scarlet oak, burr oak, pin oak, and black oak are all good choices.

And you don’t need a big property to have a happy oak tree. Although an oak can reach 100 feet tall with a crown spread of 120 feet given a couple hundred years, planted in an average-sized lawn, 20 or 30 feet from house and pavement, an oak can live its long life without causing any problems. The roots of oak trees tend to run deeper than most trees, so they are less likely to buckle your driveway or sidewalk than many other species. And oaks make great specimen trees in lawn areas because they typically have a more open canopy than maples or other big shade trees. They allow enough sunlight through to permit lawn (or native groundcovers) to grow underneath.

 Oak trees do very well on average-sized suburban properties
Even mature oaks allow enough sunlight through for lawn and other plants

Oaks do best in full sun, and average, well-drained soil. Young trees will need regular watering until their roots are well-established, but once established, oaks need very little care. Professional pruning in the first decade will assure healthy branching, but supplemental water and fertilizer is rarely needed. 

It is easy to add an oak tree to any landscape because the best practice is to start small. Transplanting a large oak can be expensive and problematic. Oaks devote most of their early life to developing the root system that will keep them healthy for several hundred years. Large specimens from nurseries have been severely root-pruned to make transplanting possible, but the loss of root structure also makes them more vulnerable to transplant shock. So, starting with a small tree, or even a sprouting acorn, is inexpensive and likely to produce the healthiest tree in the long run. In just a few years, a young sapling will catch up to a severely root-pruned specimen and surprise you with how fast it grows!

Starting a tree from an acorn is fun!
Photo: Alix Dunn
The Oak Circle at the Greenburgh Nature Center just 7 years after planting saplings

So, do this one thing. If transforming an entire landscape to native plants is not an option, consider planting a young oak tree. If you have a lawn, you already have a good spot for the most valuable keystone plant there is. 

Plant an oak tree!

For further information, read the fascinating book The Nature of Oaks by Douglas W. Tallamy

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