Nature in View – Page 3 – My Chicago Botanic Garden

Shrew-ed Observations

Several years ago, while walking the nature trail in McDonald Woods, I stopped, having heard a high-pitched squeaking emanating from the sedges and grasses along side the trail. (This was when my hearing was still acute enough to detect such high-frequency sounds.) It took me a while, but based on the emphatic commotion, I finally realized I was hearing either a romantic interlude or territorial dispute between two of the smallest carnivorous mammals in our woodland: shrews.

Actually, shrews are technically known as insectivorous mammals. Insectivores are critters that depend, to a large extent, on invertebrates, mostly insects, for their survival. I wasn’t sure which shrew this was, but more than likely, it was one of the commonest species, the short-tailed shrew (Blarina brevicauda).

Blarina brevicauda by Gilles Gonthier from Canada [CC BY 2.0],via Wikimedia Commons — Short-tailed shrew *(Blarina brevicauda)* by Gilles Gonthier from Canada [CC BY 2.0], via Wikimedia Commons

The short-tailed shrew averages about 4.8 inches (122 mm) in length, with the tail being about a quarter of the length of the body and head combined. It is by far the largest of the shrews we will see here. They are generally a velvety, dark gray color and have a conical, pointed snout. The ears and eyes are quite small and are mostly embedded within the fur. To aid in moving through the environment, and perhaps catching prey, short-tailed shrews use a form of echolocation, similar to bats, to move around in tunnels and the dark of night.

These high-energy, secretive animals are active year-round, so their presence is more noticeable when the ground is covered with snow. If a healthy population exists in good habitat, it is not unusual to spot their miniature tracks trailing away from small tunnel openings in the surface of the snow. If you are particularly lucky, you might happen upon a real nature drama where an owl has captured a shrew, leaving behind a dead-end trail of tracks and wing patterns in the snow.

Imprints in the snow of a screech owl's wings tell the story of the shrew that didn't get away. — Imprints in the snow of a screech owl’s wings tell the story of the shrew that didn’t get away.

Although short-tailed shrews are primarily crepuscular or nocturnal in their habits, they are often spotted scurrying around during the day under bird feeders in winter or around woodpiles or similar habitats other times of the year. Most people who spot shrews believe they are seeing mice, voles, or moles. In fact, some of the common names for these critters include mole shrew or shrewmouse. Mice and voles are rodents, which have incisors—those chisel-like teeth for consuming plants and seeds. Moles, like the shrews, are insectivores. The shrews, being insectivores and occasionally preying on other small mammals, have teeth designed for ripping and tearing, not unlike miniature wolves or weasels.

The teeth of the masked shrew (Sorex cinereus). — The teeth of the masked shrew (*Sorex cinereus)*

Short-tailed shrews, when active, are constantly in motion and can be easily irritated. They become aggressive if confronted by other shrews or predators. I once had a captive short-tailed shrew that I was trying to photograph in a terrarium. I placed an upright log in the enclosure for it to climb up on so I could get a better picture. As I approached with the camera, the shrew spun around to face me and leapt at the camera, then scurried away out of sight.

The short-tailed shrew has an additional distinction of being venomous. Venomous mammals are rare in nature, so this gives the short-tailed shrew a particular distinction among our local fauna. (There have been two toxins found in the saliva of this shrew: blarina toxin and soricidin.) Grooves on the outer surface of its lower incisor teeth that help inject the saliva into its prey. This venom can easily kill or immobilize the insects and worms it feeds on, but it sometimes uses the venom to help it feed on prey larger than itself and is able to subdue frogs, rodents, or even small rabbits.

Although this venom should be of concern to a mouse, bug, or frog, humans do not have much to fear. On the rare occasion that anyone would handle one of these secretive animals, the bite might burn and produce some swelling, but it is not life threatening. Interestingly, research has been conducted to investigate the use of this shrew venom in treating a number of medical conditions.

It is not unusual to find shrews lying dead on paths and in fields or woodlands. Although there are quite a few species of shrews, in our region the most common species are the short-tailed shrew and the cinereus, or masked shrew (Sorex cinereus). Just the other day, while walking along the edge of the woodland, I discovered two dead masked shrews. This is the smallest shrew species we are likely to find here, and it is also quite common. It is also insectivorus but does not have venom for subduing prey. Like hummingbirds, shrews have an incredibly high metabolism and do not live very long. In fact, much of the time they are not hunting or eating, they spend curled up asleep to conserve energy. In the case of the short-tailed shrew, however, its toxic venom probably makes it taste bad, so they are often killed but not eaten.

A long-tailed shrew, the masked shrew (Sorex cinereus). — A long-tailed shrew, the masked shrew *(Sorex cinereus)* has a pointed nose and is browner in color. It averages about 3.8 inches (97 mm), nearly half of which is its tail.

If you should be observant enough on your walks through any woodland to find an owl pellet—the regurgitated fur, bones, and feathers from past meals—you can dissect it to see what the owl has been eating. Since owls have more primitive digestive systems than hawks, the bones are not digested and turn up in the pellets. Most small mammals can be identified by examining their teeth. Shrew remains are often found in the pellets and can be quickly identified by the fact that the tips of their teeth are stained a dark brown.

Shrews are fascinating and valuable components of our natural world. Since much of their diet includes larval stages of moths, they help control many of the pest species of moths such as cutworms, army worms, spruce budworms, and other caterpillar pests of forests and gardens. Next time you are out in a natural area, keep an eye and ear alert to these miniature predators.

Autumn Asters

The harbinger of fall, for many folks, is when asters finally bloom. Their flowers look like miniature daisies and come in shades of purple, blue, white, and occasionally pink. These cool tones allow autumnal hues of yellow, orange, and red to truly pop throughout the landscape. Aster blossoms twinkle across roadsides, meadows, woodland edges, and even home gardens. Interestingly, astéri is the Greek word for star.

White wood aster (Eurybia divaricata) — White wood aster among birch trunks near the Bernice E. Lavin Plant Evaluation Garden sets the perfect fall scene.

Hosts of pollinators favor asters. The late-season blooms provide vital sustenance for adult monarch butterflies during their annual migration to Mexico. Each flower contains plentiful sources of pollen and nectar, because the central disc is comprised of up to 300 tiny florets. After pollination, a disc will turn darker and reddish, informing other insects to keep moving. In the end, birds come to consume the seeds.

Asters belong to a huge family called Asteraceae, which also includes daisies, black-eyed Susans, and sunflowers. They are mainly native to North America and Eurasia. More than 600 species once made up the genus known as Aster. However, in the 1990s, taxonomists decided to divide New World species into ten other genera. The most common ones are Eurybia and Symphyotrichum. Few nurseries adopt these names and continue to list their plants under the genus Aster.

Asters are easy to please with well-drained soil and adequate sunlight. Some even prefer shade. An assortment of heights (1 – 6 feet tall) allows them to shine in the front, middle, or back of the border. Powdery mildew is problematic for some, but you can always hide the unsightly lower stems among grasses or ferns. While pretty in nature, some asters just look scruffy in the garden. Selecting the right type is the key to a tidy look. The following asters perform best:

Jindai Tatarian aster (Aster tataricus ‘Jindai’) originates in Asia and has uniquely large and toothed foliage. From mid- to late fall, lavender-blue daisies appear in showy flat-topped clusters upon 3 – 4 foot tall stems. Best planted in the back of a bed with plenty of sun and space, its roots slowly spread into a weed smothering ground cover. Pair it with some equally tall and tough switchgrass (Panicum virgatum).

White wood aster (Eurybia divaricata) blooms for a long time, starting in late summer and lasting throughout fall. Clouds of starry white flowers are borne on 2-foot stems with heart-shaped leaves. It grows in woodlands of eastern North America where it spreads slowly by rhizomes and quickly from seed. Cut spent flower stems off if you do not want extra plants. Combines wonderfully with ferns, sedges, and shade-loving goldenrods like Solidago caesia or Solidago flexicaulis.

Avondale blue wood aster (Symphyotrichum cordifolium ‘Avondale’) is an extra-floriferous selection of an eastern North American species found at forest edges. A plethora of attractive blue flowers begin in early fall on 2 – 3 foot stems. Grows well in either sun or shade, where it adds additional color to perennials like Japanese anemone (Anemone hupehensis), monkshood (Aconitum), and the yellow fall foliage of blue star (Amsonia hubrichtii).

October Skies aromatic aster (Symphyotrichum oblongifolium ‘October Skies’) is a great alternative to New England aster (S. novae-angliae), because it is less prone to powdery mildew. With full sun, it forms a compact 2- x 2-foot mound of nicely scented foliage. In autumn, hundreds of blue-purple flowers cover the plant. The species naturally occurs across the central and eastern United States. Try it with fountain grass (Pennisetum alopecuroides).

Frost aster (Symphyotrichum pilosum) — Frost aster *(Symphyotrichum pilosum)* overflows the center plantings of the Heritage Garden.

Frost aster, or hairy aster (Symphyotrichum pilosum) is a 3- x 3-foot, clump-forming plant with many branched and arching stems. In fall, it becomes loaded with little white daisies and creates a baby’s breath appearance among flowers like Japanese anemone (Anemone hupehensis). Frost aster is common in a variety of dry, sunny habitats in eastern North America. It spreads happily by seed, so if you have too many, cut off the spent flower stems before they develop any further.

Patriotic (and rare) true blue blooms you’ll want in your yard

The fourth of July is upon us, and while many beautiful flowers can be found in patriotic shades of red and white, the color blue is very difficult to find at the Garden.

In fact, blue is a rare sight in the entire natural world. Less than ten percent of the plant kingdom features blue flowers, which is extraordinary, since pollinators don’t seem to have a problem with them. Scientists have been investigating the origins of blue flowers for a long time, and it was not until recently that they came up with a result.

Blue sea holly (Eryngium planum) — Blue sea holly *(Eryngium planum)*

Flower colors are based on pigments that include anthoxanthins and anthocyanins. Anthoxanthin colors contribute to yellow flower petals and are quite common in the plant world. Anthocyanin colors impart red, purple, and blue in blooms, but are found much less often in flora. For anthocyanin to steer blue, complex scenarios must occur. Most often, metal atoms and ions interact with the pigment to modify the color. In addition, they alter the pH of cellular fluids to be alkaline, while most organisms have an acid or neutral chemistry.

What is thought-provoking is that a red rose and a blue cornflower (Centurea cyanus) contain the same anthocyanin pigments. Cardinal flower (Lobelia cardinalis) and big blue lobelia (Lobelia siphilitica) are of the same genus, but one flower is red and the other is blue. It is the rare and complex modification of that pigment that contributes to the blue flower being blue. More surprising is that hybridizers have yet to develop a truly blue rose or carnation (without resorting to pigmenting water, which a plant takes up, changing the color of its bloom).

Royal Aspirations larkspur (Delphinium elatum 'Royal Aspirations') — Royal aspirations larkspur *(Delphinium elatum* ‘Royal Aspirations’)

Lobelia (Lobelia erinus) — Lobelia *(Lobelia erinus)*

Pacific Giant Cameliard larkspur (Delphinium 'Cameliard') — Pacific Giant™ cameliard larkspur *(Delphinium* ‘Cameliard’)

Since blue is uncommon, visitors at the Garden should take extra time to enjoy the flowers in the English Walled Garden, where they will find containers full of adorable Felicia daisy (Felicia heterophylla ‘Forever Blue’) right beside sky-colored plants called southern star (Tweedia caerulea ‘Heaven Born’)—a member of the milkweed family. In addition, there are cool-hued drifts of Magadi™ electric blue lobelia (Lobelia erinus ‘KLELE10670’) weaving throughout several garden beds, as well as spilling out of containers.

Another area with a good deal of blue flowers is the Heritage Garden. In the plant family area, you will find intricate love-in-a-mist (Nigella damascena ‘Miss Jekyll’) blossoms mingling with wispy yet showy Siberian larkspur (Delphinium grandiflorum ‘Blue Butterfly’). And nearby, nile lily flowers (Agapanthus ‘Queen Anne’) explode like bright blue fireworks. And finally, in the geographic area, sea holly (Eryngium planum) creates a shiny and spiky blue accent.

(Agapanthus africanus 'Queen Anne') — Nile or African lily (Agapanthus africanus ‘Queen Anne’)

Love-in-a-Mist (Nigella damascena 'Miss Jekyll') — Love-in-a-mist *(Nigella damascena* ‘Miss Jekyll’)

Blue Butterfly larkspur (Delphinium grandiflorum 'Blue Butterfly') — Blue Butterfly larkspur *(Delphinium grandiflorum* ‘Blue Butterfly’)

While it is difficult to achieve blue pigments in plants, the ones that did are certainly successful in this world. The word “perseverance” comes to mind, which just so happens to be what the blue within the American flag represents. Anyone who has marveled at a field of Texas bluebonnets (Lupinus texensis) and witnessed the huge number of bees and butterflies working to gather its pollen would agree.

Southern star (Tweedia caerulea 'Heaven Born') — Southern star *(Tweedia caerulea* ‘Heaven Born’)

Flying Saucers morning glory (Ipomoea tricolor 'Flying Saucers') — Flying saucers morning glory (Ipomoea tricolor ‘Flying Saucers’)

Happy Fourth of July everyone!

The Local Disappearance of Garlic Mustard

When it comes to controlling invasive plants, a little faith can’t hurt. This is particularly true for garlic mustard (Alliaria petiolata).

We have been struggling to get this highly invasive biennial plant under control at the Chicago Botanic Garden for more than 20 years. When I first began working on restoration of our 100-acre Mary Mix McDonald Woods, it took weeks of hand-pulling with many volunteers each spring to clear just 10 or 11 acres. After years of not letting the garlic mustard set seed in the McDonald Woods, a few years ago we finally began to see a light at the end of the tunnel (though we’d still end up with mountains of pulled garlic mustard each year). Thanks to the tremendous help of Garden volunteers, garlic mustard growth in the Woods has finally been curtailed, and each year we are now able to remove all flowering garlic mustard in the Woods’ entire 100 acres.

Garden volunteers pose with a pile of removed garlic mustard at an annual "garlic mustard pull" event. — Over nearly two decades, Garden volunteers have played a critical role in helping remove garlic mustard from the McDonald Woods.

About six or seven years ago, we began a new ecological restoration project in the Barbara Brown Nature Reserve (located at the south end of the Garden near Dundee Road). The area was highly degraded and choked with buckthorn shrubs (Rhamnus cathartica). After the buckthorn was removed, the following spring was a nightmare in terms of garlic mustard. Acres upon acres of garlic mustard monoculture required removing several dump truck loads just to begin making a dent in the population.

Garlic mustard takes over after buckthorn is removed from the woods. — After buckthorn was removed from the Barbara Brown Nature Reserve, garlic mustard plants completely dominated the understory vegetation for several years.

Garlic mustard became so dense in the Brown Nature Reserve that we were reluctant to pull it, since the resulting soil disturbance would greatly enhance sprouting of the soil’s dormant garlic mustard seeds. Fortunately, one of the Garden’s creative mechanics devised a basket system on a hand-held scythe. This ingenious tool allows us to harvest the plant tops by cutting and collecting the unripe seedpods—but unlike hand-pulling, using this tool completely eliminates soil disturbance.

Although the Reserve covers only six acres, in the first few years we were not able to remove all the garlic mustard plants before they began to drop their seed. This led to several more years of hand-harvesting to get the population more under control. Fast forward to spring 2017, and we’ve only found about 75 flowering plants to remove so far. What was once viewed as an impossible goal to achieve (i.e., near-total elimination of flowering garlic mustard from the reserve) has actually happened! Too good to be true, perhaps?

A handmade garlic mustard "rake" captures unripe seed heads. — This ingenious device fabricated by one of the Garden’s maintenance mechanics allows us to capture the garlic mustard’s unripe seedheads cut by the scythe’s sharp blade (the curved metal piece along the bottom).

Even with faith as small as a mustard seed, then you can move mountains: nothing will be impossible ― Viola Shipman, The Charm Bracelet

There have been recent field observations circulating in the Chicago region regarding a possible disease that apparently is having a significant negative effect on garlic mustard (see woodsandprairie.blogspot.com).

Over the past several weeks, observers have reported an almost complete absence of garlic mustard in areas that are undergoing habitat restoration—and this absence has even been observed in areas where no invasive species management has been done. Further, some restoration workers have reported garlic mustard with very “weird” rhizomes that have many small plants emerging along them. This is not at all a normal growth form for garlic mustard. The speculation is that a virus or some other pathogen is deforming and/or killing the plants. This potential pathogen might explain why we have observed such an incredible decline of garlic mustard at the Barbara Brown Nature Reserve this spring.

I have also taken note of several roadside areas along my commute to work that in past years had dense stands of garlic mustard. This spring, I’m not seeing any garlic mustard flowers there at all. Yet quite interestingly, I’m still seeing dense stands this spring in areas outside the Chicago area. What’s going on with our region’s garlic mustard?!

The next few weeks offer a great opportunity for Garden members to check their yards and other nearby areas that in previous years had shown dense stands of flowering garlic mustard. Maybe you’ll see a dramatic decline as well. Since this seems to be a very recent phenomenon, natural resource managers will need to continue monitoring to see if the decline persists.

Wouldn’t it be great if nature offers a way to rid our region of an invasive plant that has been plaguing our natural areas for so long? Stay tuned!

Take 5 steps to bring back pollinator populations

In recent years, the plight of pollinators has gotten a lot of press, and rightly so.

I spoke with the editorial board of the Chicago Tribune when they were investigating the well-intentioned distribution by General Mills of “one size fits all” wildflower seed packets to combat the declining populations of bees and other pollinators.

The decline of pollinator populations is well documented around the globe. Much attention has focused on honeybees, which are extremely important agricultural pollinators, but many of our native bees are vastly more imperiled. For example, the rusty patched bumblebee, native to the Upper Midwest, was just listed this month by the U.S. Fish and Wildlife Service as endangered.

Many people are concerned about these losses and asking what they can do to help support bees, butterflies, and other pollinators. For a start, it’s more beneficial to pollinators to plant species that are native to your region, and perennial. Here are five more pollinator-friendly actions that everyone can take.

Provide resources: For pollinators, this means flowering plants with pollen and/or nectar. Diversity is key, as flowers of different colors and shapes will attract different pollinators. Be sure to provide resources across the entire growing season, so include species that bloom in spring, summer, and fall. Regional native plants are the species our local pollinators evolved with, so they recognize and use them…and you don’t have to worry that they will become invasive!
Provide host plants: The larvae of many butterflies and moths have particular species that they need to eat to develop, as monarchs need milkweed. Providing host plants will ensure that the next generation of butterflies can mature. Just be willing to accept hungry caterpillars eating those plants.
Provide nesting sites: Many insects like to nest in bare ground, hollow stems, or leaf litter. Allowing your yard to be a little less tidy can benefit insects. Many attractive bee houses are available for sale, and do-it-yourself instructions can be found on the web.
Avoid pesticides: Pesticides are designed to kill insects, but sometimes they also kill pollinators unintentionally. Systemic pesticides can persist in plants for long periods of time and are present in all parts of the plant, including nectar and pollen. So if you choose plants for a pollinator garden, make sure they haven’t been treated with systemic pesticides. If possible, make your entire yard pesticide-free.
Learn more about pollinators: There are some great resources on the web—including those created by the Pollinator Partnership and the Xerces Society—that can help you do even more for pollinators.

Help for pollinators begins in your own backyard. These native plants below are recommended to bring back pollinator populations. (Don’t overlook trees—native maples and willows can provide critical resources early in the season.)

Beebalm or bergamot (Monarda fistulosa) — Beebalm, or bergamot (*Monarda fistulosa*)

New England aster (Symphyotrichum novae-angliae) — New England aster (*Symphyotrichum novae-angliae*)

Stiff goldenrod (Oligoneuron rigidum) — Stiff goldenrod (*Oligoneuron rigidum*)

Prairie blazing star (Liatris spicata) — Prairie blazing star (*Liatris spicata*)

American pussy willow (Salix discolor) — American pussy willow (*Salix discolor*)

Purple coneflower (Echinacea purpurea) — Purple coneflower (*Echinacea purpurea*)

Read more about the science behind this important topic in the Natural Areas Journal article, The Importance of Phenological Diversity in Seed Mixes for Pollinator Restoration by Kayri Havens and Pati Vitt, Chicago Botanic Garden.