Flowers

Some plants are not cool, skunk cabbage heats up

February 8, 2021March 22, 2021Maryland GrowsLeave a comment

Eastern 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.

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!

Delightful Daffodils

March 27, 2020March 25, 2020Maryland Grows2 Comments

Dutch Master Daffodil — *‘Dutch Master’ Daffodils in Bloom. Photo: Rachel J. Rhodes*

The signs of spring are everywhere from the sounds of spring peepers in the woods to the red hues of maple buds to the yellow blooms of daffodils. The tidbits of spring trickle in like the mist of early morning fog slowly then all at once. As if waking up from a long winter’s nap, you see buds on trees swell or the tiny green stems of bulbs that gently peak through the mulch. The next day, you hear the sounds of spring peepers. Then, all at once, the baby pink blooms of cherry trees are floating like confetti in a ticker-tape parade while crocus shine like amethyst and daffodils glitter like drops of gold in flowerbeds and all of a sudden, spring is here.

daffodils near the woods — *Photo: Rachel J. Rhodes*

As the daffodils I planted last fall leisurely woke from their long winter’s nap, I began to think about how beautiful they would be in a few weeks with their golden yellow cups and their egg yolk petals, my mind wandered to their name “Daffodil.” When I became a mother, names and the meanings behind them captivated me. As a parent, when you name your child you research everything: the meaning behind a name, where it originated from, the many spellings, and so forth. When the time came to hold my sons for the first time, I was completely and utterly prepared with names that would suit them. The names that would help define them and would help guide them as they traversed through our uncertain world. Did I put too much
weight on a name? Maybe.

As Juliet said to Romeo, “What’s in a name? That which we call a rose by any other name would smell as sweet.” There is a great name debate between Daffodils, Narcissus, and Jonquil. Daffodil refers to the common name for the spring-flowering bulbs in the genus Narcissus. Jonquil is the common name for Narcissus jonquilla within the Narcissus genus. To avoid any ambiguity, you can never go wrong by calling these flowers by their genus name Narcissus.

According to the American Daffodil Society, there are between “40 to 200 different daffodil species, subspecies or varieties of species and over 32,000 registered cultivars (named hybrids) divided among the thirteen divisions of the official classification system.” Daffodils range from the tried and true yellow trumpet to ones with double flowers and clustered flowers, to small cups, and ones with open cups. Flower colors come in an array of white to yellow to orange. There are even some with splashes of pink.

daffodil in bloom — *Photo: Rachel J. Rhodes*

Daffodils are hardy spring-flowering perennial bulbs that should return year after year. During blooming, they require generous amounts of water. After blooming, always deadhead the spent flowers. Even though daffodil foliage can get unruly, allow the leaves to remain for at least six weeks. You will see people braid or tie the leaves together with rubber bands. This timely endeavor results in the leaves manufacturing smaller amounts of food for the bulb, which in turn results in smaller blooms the following year. After the allotted six weeks have passed, you may remove the leaves.

For Maryland’s hardiness zones, plant daffodils in the fall (from late September to late November). The soil needs to be cool but the ground should still be workable and not frozen. Picking out bulbs is just like picking out the perfect apple. You want a bulb that is firm without blemishes. Bulbs should never be soft, damaged or moldy.

Daffodils are an easy dependable flower that is ideal for the beginning gardener. Don’t forget to pick some up in the fall for your garden!

By Rachel J. Rhodes, Master Gardener Coordinator, Queen Anne’s County, Maryland, University of Maryland Extension. Follow the Queen Anne’s County Master Gardeners on Facebook. Visit the UME Master Gardener webpage to find Master Gardener events and services in your county/city.

Helen’s flower hails pollinators

February 3, 2020September 15, 2022Maryland Grows2 Comments

common sneezeweed flowers — *Helenium autumnale.* Photo: Beverly Turner, Jackson Minnesota, Bugwood.org

Helen’s flower is an underdog when it comes to native plants. It is not as well known or as popular as butterfly milkweed, bee balm, or black-eyed Susans — but perhaps it’s time for its day in the sun. It makes a nice addition to a pollinator garden.

Helenium autumnale is the species name of this North American native perennial plant. It goes by the (somewhat unfortunate) name of “common sneezeweed” because dried parts of the plant were formerly used for making snuff to induce sneezing. As an ornamental garden plant, it is not known to prompt sneezes from pollen dispersal (it relies on insects for pollination) and I prefer to address it by its lovelier common name, Helen’s flower… or just plain Helenium.

Wild Helenium autumnale boasts cheerful yellow button-like flowers tended by a skirt of turned-down petals in late summer to fall. Its natural habitat in Maryland includes swamps and moist riverbanks, so in your garden, it will like a location where it has some regular soil moisture. It can grow in full sun or partial shade and stretches in height from 2 to 5 feet tall. The flowers support a variety of pollinators such as bees, wasps, syrphid flies, butterflies, and beetles.

A wide variety of cultivars of Helenium are now available. They range in color from bright canary yellow to orange and crimson and various combinations in between. Many of the cultivars tolerate drier soil and have a more compact habit.

Mt. Cuba Center in Delaware conducted field trials of 44 Helenium species and cultivars from 2017 to 2019. They evaluated plants for their habit, vigor, disease resistance, floral display, and pollinator visits.

helenium flowers in a garde — *Helenium flowers in a garden, “The warm glow of early Autumn” by hehaden, Flickr*

Given the high interest in pollinator gardens right now, I was curious about their observations of pollinator visits in particular.

The native Helenium autumnale had the most observed pollinator visits (162), while the cultivar H. ‘Zimbelstern’ came in second (151). Both of these had excellent powdery mildew resistance as well. Other cultivars such as Helenium autumnale ‘Can Can’ and H. ‘Tijuana Brass’ also had excellent ratings for these two characteristics. The best performers in the study overall (considering all the characteristics evaluated) were ‘Kanaria’, ‘Zimbelstern’, and ‘Can Can.’

The native Helenium autumnale had the most observed pollinator visits (162), while the cultivar H. ‘Zimbelstern’ came in second (151).

For all the details and results of the evaluation, read the report online.

If you plan to start (or add to) a pollinator garden this spring, do consider adding Helen’s flower if you have a moist site in full sun or partial shade. Mt. Cuba’s report provides good information on plant care, including staking and pruning tips and recommendations for managing the two most common diseases — powdery mildew and aster yellows.

To purchase plants, check the Maryland Native Plant Society’s website for spring native plant sales and nursery sources.

Visit the Home & Garden Information Center website for additional resources on native plants and gardening for pollinators.

By Christa K. Carignan, Coordinator, Digital Horticulture Education, University of Maryland Extension Home & Garden Information Center. Read additional posts by Christa.

Winter sowing: How I get a jump start on my summer flower garden

January 23, 2019January 23, 2023Maryland Grows9 Comments

poppies — *These June-blooming flowers were started by winter sowing. Photo: C. Carignan*

Winter sowing is a technique gardeners can use to start growing seeds outdoors during the winter months. If you have limited space for starting seeds indoors, winter sowing might be an option for you, depending on what you want to grow.

I first tried winter sowing last year with several types of flower seeds. Winter sowing works best for plants that are cold tolerant or even require a period of cold in order to germinate. When you are looking at seed descriptions, look for words like “cold tolerant,” “cool season”, “hardy annual,” “perennial”, “sow in autumn”, “sow in early spring”, or “self-sows”. These words indicate the best candidates for winter sowing. Continue reading →

Cardinal Flower Is for Hummingbirds

August 10, 2018October 19, 2022Maryland Grows2 Comments

I gave up on my hummingbird feeder years ago. It was more than I wanted to do to keep up with changing the sugar solution every two to three days, as recommended to keep the food free of spoilage that could be harmful to the birds. I saw that hummingbirds would visit some of my garden flowers just as much as the feeder, so I decided just to provide flowers for them. More flowers for me, more natural nectar for them. A win-win.

In my garden, ruby-throated hummingbirds most often fed at my scarlet bee balm, blue salvias, brilliantly colored zinnias, and orange butterfly weed. This year they have an additional choice that appears to be their new favorite. It is the flower whose color resembles that of a different bird, cardinal flower (Lobelia cardinalis).

This Maryland native plant produces 2-4′ tall spikes of bright, cardinal-red flowers that are irresistible to hummingbirds in mid to late summer. In fact, hummingbirds are an essential pollinator of these plants.

Cardinal flower was easy for me to grow from seeds sown directly outside. In the fall of 2016, I scattered seeds in a low area of my yard where water frequently would puddle after heavy rain. They sprouted and grew low foliage and a few small flower spikes the following season. This year I have plants that are well established and the flower spikes are tall and brilliant. Cardinal flower grows best in moist to wet soils, so this has been a fabulous year for it!

If you have a shady or partially shaded area that tends to stay moist in your yard, cardinal flower might be a great choice for you. Allow these plants to reseed naturally so you’ll have flowers — and a natural hummingbird feeding station — year after year.

Additional Resources

By Christa K. Carignan, Coordinator, University of Maryland Extension Home & Garden Information Center

Q&A: What’s wrong with my hydrangea flowers?

August 6, 2018March 11, 2022Maryland GrowsLeave a comment

Q: My hydrangea bloomed white but instead of turning red it turned brown. What is happening to the petals and what can be done?

A: A disease called Botrytis blight can cause spots and browning symptoms on the flower petals of Hydrangea and other types of flowers as well. Extended periods of cloudy, rainy weather like we had recently can favor the development of this fungal disease. Botrytis first appears as water-soaked spots that gradually expand into brown blotches. There is no remedy for this damage. Prune out and dispose of the damaged flower parts.

The spotting on the leaves is common on Hydrangeas in late summer, especially in our humid climate. Leaf spots can be caused by fungal and bacterial pathogens. The leaf spots are mainly a cosmetic problem. They will not kill the plant. Chemical control is not recommended in most home garden situations.

Keep Hydrangeas watered regularly during drought periods and avoid overhead watering to minimize wetness on the flowers and foliage. Clean up and dispose of symptomatic leaves at the end of the growing season.

Visit the Home & Garden Information Center website for more information on common problems of trees and shrubs.

By Christa K. Carignan, Coordinator, University of Maryland Extension Home & Garden Information Center

Have a plant or pest question? University of Maryland Extension’s experts have answers! Send your questions and photos to Ask an Expert.

Hibiscus sabdariffa

September 6, 2012June 24, 2022Maryland Grows11 Comments

One of our favorite plants this year at the Derwood Demo Garden is Hibiscus sabdariffa, or roselle hibiscus (or sorrel, sour-leaf, flor de Jamaica, and many other names). It is an Old World plant (Africa and Asia) that is also grown extensively in the West Indies. In its natural warm habitat, it can be a woody shrub, but here it’s grown as an annual. I started the seeds inside in March and by July it was over two feet tall.

The roselle flower looks a lot like that of okra; they’re in the same plant family, Malvaceae. One of the useful parts of the plant is the flower bud:

which is picked when about an inch long and completely red. To make a simple nutritious infusion, use 2-3 buds per measured cup of water, and simmer the buds in the water for about ten minutes until the water is a rich red. You can drink this tea hot or cold, and add herbs to it for variety. The commercially sold Red Zinger tea has roselle hibiscus as its base.

MG Millicent Lawrence told me how roselle or “sorrel” is used in Jamaica for a winter drink (alcoholic). Here’s her recipe:

Jamaican Sorrel

Ingredients (makes about 2-3 pints of liquid)

1 cup dried sorrel buds

2 Tbs grated ginger (no need to peel)

5 cups boiling water

10-20 allspice (pimento) berries. If the allspice berries are large (pea size) use the lower amount

rum and sugar to taste

wine (optional)

Place the sorrel, ginger, and allspice in a large container and pour in the boiling water. Cover and let steep overnight. Strain through cheesecloth or a fine meshed sieve to remove all solids. Add a little rum to preserve and sugar to sweeten, and wine if desired. Pour into a glass bottle and refrigerate. The end product should be a rich ruby-colored spicy beverage.

You could also use fresh buds for this, but you’d need much more than a cup, and you’d need to infuse them, not just pour boiling water on. Dried sorrel or flor de Jamaica can be found at Hispanic groceries.

credit Barbara Dunn

This aerial shot of the demo garden was taken from a kite flown by the indefatigable MG Barbara Dunn.

You can see our fat patch of roselle hibiscus next to the blue-green coiled hose. There are perhaps seven plants in there – I can’t remember now – and the patch is about seven feet long.

Here’s a closeup of the pretty leaves – look, no bug damage! And it turns out the leaves are edible as well. I’d read this but hadn’t tried them, and then a very nice Burmese-American visitor to our garden saw the plant and recognized it and asked for some leaves to show us how it was cooked – and the next week we got a dish with “sour leaf” and bamboo shoots to sample.

I took some home that night and cooked them, but I won’t post the recipe because I’m still working on it. The leaves have a strong sour taste that needs to be complemented with other tastes, and the Indian spices I used weren’t strong enough to do the trick. I ought to have properly caramelized the onions, too.

Here’s a shot of my dinner, accompanied by a glass of roselle infusion. I served the roselle greens on a chickpea flour pancake (recipe here, from a delightful food blog).

So give roselle a try in your vegetable or flower patch next year! The seeds are available from Southern Exposure Seed Exchange and other sources (more next year, I expect, since this is a hot plant in the food gardening world right now).

Maryland Grows

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