Wild ginger spices up the Maryland spring

As a pollination biologist, I have the immense privilege of studying really cool plants who trick their pollinators in fancy and incredible ways, and I tend to be naturally attracted to flowers that may not be super showy to most (but are among some of the most mind-blowing things in nature). These flowers are such a wonderful thing in their own right, and in this post I want to do them justice. Because it’s spring and some of these are starting to point their noses out of the ground, in today’s post I would like to (re)introduce you to a plant you may be familiar with, but that I hope after today you will get to look at with new amazed eyes (in case you don’t already 😉 ). Come with me and let’s chat a bit about the wonderful hidden queen of our forests: the wild ginger!

Is wild ginger, ginger?

The short answer is no. While ginger (the plant we eat) is native to Southeast Asia, wild ginger (Asarum canadense) is native to right here, and more specifically to the deciduous forests of Eastern North America. In case you are not familiar with the plant, it belongs to the family of birthworts, which have really interesting ways of interacting with their pollinators. Unlike other birthworts that tend to have flowers that hang in the air from the plant, wild gingers are very “shy” and the whole plant is restricted to the ground level.

Wild ginger is starting to peek out their leaves right now. Once the leaves are fully grown, they get their characteristic heart-shape and can create nice mats to cover the ground. Photos: A. Espíndola; threelark.

The plant is perennial (it lives for several seasons) and exits dormancy in the early spring when its heart-shaped and fuzzy leaves start to unfurl and emerge from the ground. Eventually, the plant becomes a little mat and over time it creates colonies. This is a reason why wild ginger can be a great groundcover plant to use under trees or in shadier and humid parts of one’s yard (see here for how to do this).

Wild ginger is cool – The flowers!

Unlike other birthworts, wild ginger holds its flowers close and parallel to the ground. Wild ginger’s flowers are not showy, being of dark brown and not very large. These flowers are engaged in mimicry pollination, meaning that “disguise” as something else (here, fungi), to trick pollinators into doing something they don’t necessarily want to do. In the case of wild ginger, the flowers are held low to the ground and close to the base of the stems.

Wild ginger flowers are displayed on the ground, at the base of the fuzzy stems. Being dark and close to the ground helps them lure their pollinators, small flies that feed on decaying matter. Photo: A. Carlson.

Wild ginger flowers are dark, particularly moist, and produce specific odors that attract small flies that feed on decaying matter. The tricking consists in making the flies enter the flowers to lay eggs in what the flies consider is fungi (their egg laying sites). While doing this, the flies contact the pollen-bearing structures, and while visiting different flowers, they cross-pollinate them. In this case, we talk about antagonistic interactions between the plants and their pollinators because the interaction does not benefit both partners. In fact, here the plants have the upper hand, and the flies simply loose their eggs to the plant since their larvae can’t feed on the floral tissues. If this is not sufficient to amaze you, keep reading; it gets better!

Wild ginger is cool – The seeds!

After pollination, the flower ovules grow into seeds. Unlike seeds in most plants, wild ginger seeds have a special “addition”. Indeed, the seeds have attached a special extension (called an elaiosome) that is particularly rich in lipids and proteins. This structure makes the seeds very attractive to ants, who collect the seeds, carry them away from the plant, and, after having consumed the elaiosome, discard the seed. By doing this, the seeds can get dispersed farther away from the mother plant, and the population can slowly grow and expand. Isn’t that super neat????!!!

The seeds of wild ginger have a special nutrient-rich body called elaiosome, which is a delicatessen for ants. This allows the plant to use ants to disperse their seeds. The shiny brown (left) and yellow (right) bodies attached to the seeds are the elaiosomes (arrows). Photos: Sid Vogelpohl, Arkansas Native Plants Society; B. Patterson.

Wild ginger as a human ally

Wild ginger was and is still well known to Native Americans of Eastern North America, and it is very likely that they were the ones who showed the European colonists how to use it. Among the Native names still known for this plant is namepin (see here to learn how to say it), which means “plant of small tubers”. Even though it is hard to find the original local names for Maryland tribes, we know that the roots of the plant were used to treat fever and coughs by Cherokees, Iroquois, and Rappahannocks, and that it is very likely that most of the tribes and bands of Maryland (e.g. Shawnee, Piscataway, Pocomoke, Assateague, Nause-Waiwash, Accohannock) use(d) it as well because the plant was and is abundantly present in the area.

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

New! Anahí also writes an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish speaking friends and colleagues in Maryland. Bienvenidos a Extensión en Español!

Hummingbirds Add Grace to the Garden

In a few weeks, they will return; flashes of emerald green winging their way through our gardens. The hummingbirds will be back.

Around April 15, hummingbirds return from their winter digs.  Weighing about the same as a dime, they pack plenty of power in that petite package.   Their wings beat 50 times a second and their aerial acrobatics are second to none. 

Our local hummingbird is the ruby-throated hummingbird.  The males sport a jaunty red handkerchief of feathers they flash to attract females and warn off aggressors.  Hey, baby.  Whoa, bud. 

As they dip their bills into flowers, hummingbirds pick up pollen on their feathers which they transfer to other flowers.  Bees and butterflies get all the press, but hummingbirds also are good pollinators.

Hummingbirds’ powerhouse metabolism needs constant fuel.  One hummingbird needs the nectar from about 1,000 blossoms a day to survive.  As gardeners, there is much we can do to help these flying jewels.

To attract hummingbirds to your garden, plan blooms from April to October to provide them with a steady source of nectar.  They supplement their diet with tiny insects and spiders, but it’s nectar they need most.

A perfect addition to your garden is the native columbine, Aquilegia canadensis.  It blooms in concert with the hummingbirds’ arrival in April when few flowers are blooming. Plus, it has the tubular form that’s custom-made for a hummingbird’s long, slender beak.

The rumors are true:  hummingbirds favor red and orange flowers.  If they also have a tubular shape, your hummingbirds will be ecstatic.  Think coral honeysuckle, salvia, and bee balm. 

Some plants fool you by having a hidden tubular base.  Look at a petunia, morning glory, lantana, or phlox to see what I mean. 

Nectar-heavy flowers without tubular shapes score big with hummingbirds, too.  Lupines, hollyhocks, and foxglove are all favorites.

Plants provide wonderful natural food sources for hummingbirds, but many people – myself included – like to put up hummingbird feeders.  The best feeders are sturdy, easy to clean and hang, and have multiple ports and perches. 

Skip the pre-made hummingbird food mixes and make your own.  Simply dissolve 1 part sugar in 4 parts water.  I boil a cup of water and add a quarter cup of sugar.  Clean and refill your feeders weekly. 

Hummingbirds prefer showers to baths, so you can make them oh-so-happy by adding a water dripper or mister to your garden.  They will delight you by dancing in the spray.

If you’d like to help your hummingbirds even more, avoid using chemicals in your garden.  Their fast metabolism and tiny size make them especially vulnerable to insecticides and herbicides.  So, use kinder, gentler controls.

I hope you will welcome hummingbirds into your garden this year.  There are few sights more joyful, few birds more charming.   

Some plants are not cool, skunk cabbage heats up

IMG_3725-eastern skunk cabbage at pine hole bogEastern skunk cabbage at pine hole bog by dreamexplorer is licensed under CC BY-NC-SA 2.0

The middle of the winter may seem like an odd moment to think about flowers. In fact, if I look out my window, I can barely see the ground, with most of it covered in snow or ice. So, flowers and all the greenery of spring and summer seem like something that happened in another world which today seems sooooo far away! There are some flowers, however, that defy some of these rules of low temperatures and do a revolution in nature (OK, maybe not a revolution, but still…). In today’s post, and although surrounded by ice and snow, I invite you to join me and warm up using the heat that some plants produce, since we’ll be talking about heat-producing plants!

Really?! Can plants produce heat?

The short answer is yes, which is super cool in itself. The long answer is yes, but let me tell you how, and what are the advantages of producing heat (and why not all plants do it).

The production of heat in plants is relatively rare, and this feature is found mostly in plants considered to have evolved a long time ago from an ancestor to most living plants. Today, heat production in plants is restricted to groups associated mostly with tropical and subtropical environments, such as water lilies, aroids, palms, and birthworts.

Unlike what we may expect, heat production in these groups has not evolved to keep the plant alive, but rather to help the plant reproduce. In these groups, heat production is associated with floral maturation and in particular to pollinator attraction. In these cases, different parts of the flowers increase their metabolism at a specific point in their development, leading to an increase of temperature that in some cases can be extremely noticeable.

In some cases, the heat has been described as a reward for pollination. (Check out this other post for other “special” rewards pollinators get from plants.) This is because it may occur at times of the year (or the day) when the environmental temperatures drop a lot, and when pollinators that visit the flower could benefit from an extra source of heat.

In other cases, heat is known to promote the release and spread of floral odors, which attracts the preferred pollinators. In many cases where heat production is present, it has been observed that plants also display a way to retain the pollinators, such as floral chambers, and in many of those cases the interaction between the plant and its pollinators involves luring and temporarily trapping the pollinators!

plants in the arum family
Some arum family plants (here, the European Arum maculatum) temporarily trap their pollinators. The species shown here displays a chamber in the lower part of its “flower” that is closed by hairs (shown on the right), which let the insects in but makes it hard for them to leave. While the flies are trapped in the chamber, the flowers mature, dropping pollen on the flies. These flies will be released after a while, and some of them will be caught again by another plant, leading to the cross-pollination of the species. Sneaky, sneaky! Photos: A. Espíndola.

While it takes a lot of energy from the plants to produce heat, this usually allows them to flower early in the season while other flowers are not around. This reduces inter-plant competition for pollinators, makes the plants easy to find by pollinators, and increases the chances of having pollen be transferred from one flower to another — all of which increases the number of seeds plants are able to produce.

Our very own heat-producing plant, the Eastern skunk cabbage

Many of you may be familiar with Eastern skunk cabbage (Symplocarpus foetidus), which is among the first plants we see peek out their leaves in the snow or the ice in the early spring. Besides being among the first plants to appear in our region, they are actually also among the first to flower, and that flowering and their pollination are intrinsically related to heat production.

Skunk cabbages belong to a mostly tropical family of plants, the arum family (Araceae). Fortunately to us, some of them do occur also in more temperate regions like ours (another native Araceae from our region is the beautiful Jack-in-the-Pulpit, Arisaema triphyllum). As with many other Araceae (for example, the titan arum), skunk cabbage attracts their pollinators through the production of a very pungent odor, which gives the plant its common name. And like all Araceae, their flowers have a very special shape that allows them to not only produce but also retain heat.

skunk cabbage
The skunk cabbage has a typical arum family flower with a bract that covers the central part of the flower. The central part displays all the reproductive parts. In the picture shown here, it is possible to see the yellow pollen exposed on the flowers of this plant. During flower maturation, the reproductive part heats up, reaching temperatures of over 20˚C (about 70 ˚F)! Center and right images show pictures of the flowers taken using a camera able to measure surface temperature, with a color scale that relates shown colors with temperatures. Photos: left: Janet and Phil; center and right: Onda et al. 2008.

When their flowers start to mature, the “head” of the flowers heats up reaching temperatures of about 70˚F (!!!), even if the surrounding temperatures are below freezing. This heating leads to the release of aromatic odor bouquets, formed mostly by compounds rich in sulfides (thus, the stinky odor). Even though this odor may not be the most attractive to us, it is very much so to the skunk cabbage’s favorite pollinators: small flies and beetles that may be lured by the flower “thinking” it is their favorite food or egg-laying site.

In defense of the plant, though, even though the attraction may be slightly dishonest, the lured pollinators may actually benefit a bit from the visit. While some of them may indeed find laying sites on the plant material, most of them will benefit from the heat received, which especially that early in the season is a much welcome reward! This heat also allows the pollinators to become more active and sometimes even mate within the plant’s flower, which also benefits their own reproduction. Finally, and most importantly for the plant, through this heat release and all the insect movement associated with it, insects passively pollinate the flowers, getting covered in pollen and later transferring it to other equally stinky and warm skunk cabbage flowers. Isn’t this super cool?… I mean, warm?

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.

New! Anahí is starting an Extension Blog in Spanish! Check it out here, extensionesp.umd.edu, and please share and spread the word to your Spanish speaking friends and colleagues in Maryland. Bienvenidos a Extensión en Español!

Readers’ 2020 Gardening Highlights Vol. 2

At the end of 2020, we asked readers to share any notable stories, projects, or accomplishments from their past year in gardening activities. We received some great submissions. We will feature a portion of the submissions in this post and more in the future.

View more 2020 Highlights

Pollinators love Mexican sunflower

Anne Henochowicz in Montgomery County wanted to share her success with this pollinator attracting plant.

Pumped about pumpkins

Kelly Domesle and daughter Helena had great success with pumpkins down in Washington D.C.

“During the shutdown this Spring, we spent an afternoon exploring the physics of “Pumpkin smashing” from our deck. My daughter, Helena, salvaged a few pumpkin seeds and planted them in our front yard. I was skeptical, but she tended to the plants all summer and had an amazing harvest this Fall! People stopped and talked to us about our pumpkin patch all year and we loved watching the bees buzzing in and out of the flowers. We gave the pumpkins away to neighbors and cooked some, too.”

  • Pumpkin harvest
  • Big pumpkin patch
  • Pumpkin vine

Brittany’s bountiful Baltimore garden

Brittany Croteau, a Master Gardener in Baltimore City shared her amazing turf reduction/garden expansion, native flowers, and fruit and vegetable haul this year:

“Over 2020 I anticipated having a really sad garden year… I was newly pregnant, and had just accepted a promotion which had me traveling to Cecil County daily, which left me with little time to think about my garden. Then COVID hit and I found myself at home 24/7, with a LOT of free time on my hands. My husband and I decided to rededicate that time to our garden, removing more turf, planting more natives, and meeting (socially distanced) with neighbors to swap produce and flowers. This year was the most fruitful garden we had, both with native plants, native birds, and veggie production. I was so grateful to spend time outside and create a space I was happy to welcome my daughter into in August 2020. A year I thought my garden was going to be neglected ended up being our best garden year yet. “

The Itchy Truth About Poison Ivy

poison ivy vine climbing a tree
Poison ivy uses hairy aerial roots on its vines to cling to trees. Photo: Betty Marose

It starts with a twitch and an itch. Then it grows into full-blown scratchiness and dreadful knowing. You have poison ivy. Again.

I tip my hat to those immune to the maddening rash that contact with this plant brings. You are indeed the Fortunate Ones. The rest of us will try to quiet our whimpering.  

It pays to know the enemy. Poison ivy is a perennial plant that can climb trees as a vine, form a shrub, or snake over the ground. It spreads by seeds and rhizomes, sneaky underground stems that help it form colonies. 

A native plant whose berries feed over 50 species of birds, poison ivy has glossy leaves, attractive berries, and striking fall color. If it weren’t for the itch, we’d love it. 

The key to managing poison ivy is learning to recognize it. “Leaves of three, let it be,” is a wise adage. Most poison ivy has three pointed leaflets that form one compound leaf. 

young poison ivy plants have three leaflets
Poison ivy has compound leaves with three leaflets which inspire the phrase, “Leaves of three, let it be.” Photo: University of Maryland

Nearly all poison ivy leaves have wavy or toothed edges, but some are smooth. In spring, they are shiny and reddish, turning green as they mature. In the fall, leaves turn yellow, orange, or red.

Another giveaway is poison ivy’s hairy vines bristling with aerial roots that help it cling to trees.

Lookalikes abound. Virginia creeper has similar leaves with 5 leaflets to each compound leaf. Box elder seedlings have nearly identical 3-part leaflets. When in doubt, steer clear.

To help you tell the real deal from imitators, we’ve created a handy identification guide with photos here.

Every part of the poison ivy plant – leaves, stems and roots – carries an oil called urushiol that irritates skin. Even dead plants can cause a rash.  

Symptoms of exposure – itching, burning, swelling, rash and blisters – can show up a few hours to a few days after contact. You can also get it from tools, clothing, or pets.  

How do you prevent the torment that is a poison ivy rash? Learn to identify and manage the plant and treat yourself after possible exposure.  

Cover up well with long pants and shirt and gloves and dig out, bag, and trash small plants. Or spot-spray foliage of small plants with a non-selective herbicide with glyphosate, being careful to avoid desired plants.  

Penn State University advocates using the “glove of death.” Don nitrile or other chemical-resistant gloves, then cotton gloves, and wipe a glyphosate solution onto small plants.   

If poison ivy vines are growing up your trees, cut the vines to starve the top. Never burn poison ivy. That can send its irritating oils into the lungs and you to the hospital.

The best time to treat poison ivy is early to mid-summer when it’s actively growing, but now is not too late. After contact, wash clothing separately from other laundry and carefully clean tools.  

Now you have the tools to identify and manage poison ivy. Forewarned is forearmed. And much less itchy.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.

Why Do Pollinators Visit Flowers? Hint: It’s Not Just for Nectar and Pollen

Other than because I think they are pretty, I love looking at plants and their flowers. In fact, one of my pastimes has become figuring where and what is the reward that pollinators get out of their visits to their favorite flowers. You may be now thinking that my pastime is a bit nonsensical, since it is pretty clear that pollinators get pollen and nectar from flowers, so why bother checking? Well, actually, that is only partially true; did you know there’s a myriad of rewards that pollinators can get from their flower visits?

In today’s post I want to tell you a bit about some of those other rewards; the ones that fascinate me so much. Let’s talk about special floral pollination rewards and where you can see them in real life!

We like essential oils, some pollinators like floral oils!

The first time I heard about floral oils my mind was blown in such a way that I became obsessed with them, to the point that now a large part of my research program focuses on them. Floral oils are a reward that many types of plants offer to their favorite pollinators: oil-bees.

But don’t let me get ahead of myself! Floral oils are a special type of oil – different from essential oils – that are produced and presented to pollinators on different parts of the flowers of some plants. Independently of what exactly they look like, all these plants are visited and pollinated in a very specialized way by oil-bees. Unlike honeybees, these oil-bees are solitary and make their nests in the ground. These oils help these bees line their nests to waterproof (!!) and strengthen them. Along with that, they also mix the oils with pollen and feed that ‘pollen ball’ to their larvae.

Macropis oil bee
The whorled yellow loosestrife (left; photo: Eli Sagor) is one of Maryland’s native plants that offers floral oils to their Macropis oil-bees (right; photo: Don Harvey). Note the shiny load of oils and pollen on the hind legs of this Macropis!

Oil flowers are present all around the globe. In our region, they are represented by several species of the yellow loosetrife plant genus Lysimachia. With their floral oil rewards, these loosestrifes sustain the rare oil-bees of the genus Macropis. At the level of the country, most oil-flowers (and their specialized pollinators) are restricted to the Southern USA, where they are visited by the large bee genus Centris. Some of these plants are the wild crapemyrtle, the prairie bur, and the purple pleatleaf.

Hungry? Please, help yourself!

Along with nectar, pollen, and floral oils, food for pollinators can come in many different shapes and forms. In fact, some flowers even offer parts of their flowers to their pollinators. In cases like this, flowers develop special structures – usually around their petals – with the only function of becoming food for pollinators. Flowers providing this type of reward are usually pollinated by beetles, who can use their strong mandibles to chew on and eat the special structures.

calycanthus
Sweet shrubs display nutritious structures to their pollinators, small sap-feeding beetles of the family Nitidulidae. Photo: Wikipedia commons.

One of the coolest examples of the use of this type of reward is our very own sweet shrub, Calycanthus floridus. This spring flowering plant (flowering right now in Maryland!) attracts small beetles that enter the flower and stay there for quite some time. To maintain and support them while they are helping the plant reproduce, the sweet shrub flowers englobes them during parts of their flowering (this is why sometimes these flowers seem to be opening and closing throughout the day) and present small extremely nutritious structures at the base of their petals. It is on these structures that the beetles can feed on to stay strong and healthy while they are on the flowers. If you have one of these flowers in your yard, or happen to see them in one of your walks, take a second to stop and check them; you may get to meet their little beetle friends! 

Need a hand taking care of the kids? Here I am!

Some other flowers have established even more intricate relationships with their pollinators, and what they provide is not just food, but also a house! Because in these plants the offered reward is a place for the larvae of these pollinators, these interactions are called ‘nursery pollination’. Here, the pollinator visits the plants, collects pollen, and sometimes even actively places pollen on the flower tip. By doing so, the pollinator makes sure that the plant seeds develop. This is important, because their larvae will need some of them to feed on throughout their development.

yucca moth
Joshua trees (left; photo: Shawn Kinkade) are some of the most iconic plants of the US Southwest. These plants offer a brood site to their super-specialized small moth pollinators (right; photo: Judy Gallagher).

Along with this being the reward we see in a plant we love to eat (figs!), one of the most spectacular examples of the use of this reward is found in an iconic plant of the deserts of the US Southwest, the Joshua tree. Indeed, Joshua trees produce flowers that are visited by a group of moths, the Yucca moths. These moths visit the flowers, collect their pollen, and then literally push it into the flower tip to actively pollinate it. Because the moths lay eggs on the flowers, this assures that the flower develops seeds so the larvae have something to feed on. What is fascinating, though, is that these larvae never eat all the seeds, so this really is a win-win relationship between the plant and the moth.

To see how this is done, take a look at this video!

yucca moth video
Larvae of the Yucca moths feed on a Joshua tree’s seeds. To make sure that there is something for their larvae to eat, these moths actively pollinate the plants, exchanging a brood site for pollination, and in the process display some of the most fascinating behaviors one can see in pollinators. Check out the video to see it for yourself! Video: University of Nebraska-Lincoln. 

By Anahí Espíndola, Assistant Professor, Department of Entomology, University of Maryland, College Park. See more posts by Anahí.