Ragweed = Food of the Gods?

The Indianapolis Star reported last week that this is a terrible year for allergies.  Adults who have never suffered symptoms are being even being affected.  The severity of hay fever problems was attributed to the mild winter and summer drought.  I was happy to see that the photo that accompanied the article was one of ragweed (Ambrosia sp.), correctly identified.  Often on TV, and once previously in The Star, photos of plants in hay fever stories show the seeds of dandelion or a related plant.  I guess this is because pollen, the major trigger of hay fever, is too small to show easily.  While we can all related to seeing dandelions seeds spread by the wind, they don’t tend to end up in our noses.

Wind pollinated plants cause hay fever.  Ragweed is a classic.  Its long spikes of flowers are

Ragweed in flower in all its glory.

essentially made up of either all female reproductive parts (carpels) or male reproductive parts (stamens).  These plants do not rely on insects to vector, or carry, pollen from flower to flower to fertilize seeds.  Instead their strategy is to produce copious wind-blown pollen that must land by chance on the correct flower part to be able to fertilize an egg.  This strategy is chancy, so much pollen is made to increase the odds.  Wind pollinated species do not invest energy in making showy flowers to attract unneeded pollinators.  Indeed, petals would get in the way of wind-blown pollen transport.  This is why ragweed and other wind pollinated plants are often overlooked in flower; flowers are greenish and dull.  Grasses, some that bloom in the spring and some in the fall, are another plant group that uses wind to spread pollen.  So are hardwood trees that bloom in the spring.

Giant ragweed (Ambrosia trifida) is a native species that can grow 10 feet or taller.  Its most characteristic features are its three-parted leaves and spikes of flowers. 

Giant ragweed leaf.

Male flowers look like yellow clusters or packages of pollen close-up.  The genus name Ambrosia means “food of the Gods.” No one is sure why.

Male ragweed flowers.

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Tree-of-heaven, Ailanthus altissima, is a beautiful name for a pest tree.  I have heard it is one of the few species illegal to plant in Indianapolis, due to its tendency to spread aggressively via seed.  Male and female flowers are borne on separate plants.  Single female trees can produce thousands of wind-borne seed.

Tree-of-heaven on the Butler University campus.

It is a native of Asia where it apparently got its common name from growing so fast to reach heaven.  Twigs have the density of balsa wood.  I use them to help students learn to recognize the characteristics of twigs, like leaf scars and bundle scars, because these features are so large on Tree-of-heaven. 

This tree is the one immortalized in the book A Tree Grows in Brooklyn and, indeed, I did see if growing there when I spoke at the Brooklyn Botanical Garden this spring. 

Tree-of-heaven can grow quite large.  There is one in a backyard across from Binkley’s on College at Kessler

Tee-of-heaven’s very large leaves, with many leaflets on a single leaf, and wind dispersed seeds.

Ave. that my husband and I see every Monday late afternoon during discount draft day.  Even in this dry summer it had an impressive display of flowers and seeds. 

The plant also sends up multiple shoots from the same rootstock, resulting in patches.

Tree-of heaven is one of 30 trees featured on the Butler University tree walk.  For more a brochure or more information on the walk, visit www.butler.edu/herbarium.

The Butler University tree walk.

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Sidewalk Weeds in the Hot Dry Summer

I’ve been paying more attention lately to urban wild plants, often what we would call weeds, which appear spontaneously in places like crack in sidewalk.  One of the more prettiest, even without flowers,  is purselane (Portulaca oleracea) and introduced mostly creeping plant with succulent-like stems and leaves.  

Purslane and sidewalk

Purslane seems to be enjoying the weather this summer, looking plump even in the drought.  Although I have never tried it and don’t advise foraging plants from the wild, my friend Phyllis routinely eats this plant when it appears in her vegetable gardens.  It is apparently a tasty salad green.  The fleshy stems and leave do not look appealing to me.


Purslane's fleshy leaves and stems. Small yellow flowers aren't open on this plant.



The last year or so I have noticed in increase in another prostrate weedy creeper – carpetweed (Mullago verticillata).  Its common name is very apt.  It has small white flowers and is decorative in its way, but a single plant can spread out over a large area quickly.

Part of my increasing appreciation of weeds comes from reading the very interesting book

Carpetweed and sidewalk

WEEDS: In Defense of Nature’s Most Unloved Plants By Richard )MabeyEcco/HarperCollins Publishers. 324 pp. $25.99 papperback $14.99).  It chronicles the importance of weeds in England through history, from early agriculture to herbals to today’s urban settings.  Many of these weeds are familiar to us in Central Indiana.  I highly recommend this book.

Carpetweed lives up to its name

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Queen Anne’s Lace – a roadside beauty

Along with Chicory (see below), Queen Anne’s lace (Daucus carota) is one of the great roadside wildflowers.  The common name comes from the beautiful white flowers.  They are clustered into flowering stalks called umbels, with what looks like a single flower at first actually being a bunch of umbels each made of a group of individual flowers that arise from the same spot. 

Queen Anne's lace

Umbels look like tiny umbrellas (maybe from the same root word?). Queen Anne’s lace is in the carrot family, the Apiaceae, formerly called the Umbellifera because to the distinctive flowering stalks found in the group of plants.  Often inflorescences, or flowering stalks, are a key to the family a plant belongs to.

 Queen Anne’s lace is native to Europe.  It is the species from which the domesticated carrot was derived.  Wild plants have somewhat fleshy tap root. Their leaves definitely look carrot-like.

Note dark colored single flower in center of inforescence of Queen Anne's lace

Some inflorescences have a single black or dark purple flower in the center.  This is thought to make it more attractive to pollinators.




Lots of Queen Anne’s lace can be seen around Indy this summer, even with our heat and drought.  I nice stand is in the formerly landscaped area near the sidewalk at the former Bee Windows store on 54th Street near the Monon. 

Field shot of Queen Anne's lace




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Chicory – a great roadside wildflower

Chicory flowers - photo by Marcia Moore

Chicory (Cichorium intybus) is a striking wildflower on display this month.  It is a common roadside weed that grows so densely sometimes that it looks as if it was planted. 

There is a stretch of 38th St. near the parking area by the basketball sculpture at the Art and Nature Park that really looks this way.  Maybe the early spring and cities cutting back on mowing schedules has led to the increased visibility of Chicory this year.  It often grows with Queen Anne’s lace, a really nice roadside combination.

Chicory flowering head - photo by Marcia Moore

It has long been one of my favorite wildflowers/weeds.  A member of the sunflower family, it has composite flowering heads that are all ray flowers, no disc flowers.  Each head is only open for a day.  The color is a rare light purple/blue – even the anthers and pollen.  Plants are perennials with a milky sap.

This plant is introduced to our area. Chicory is found in cities all over the globe, probably due to its usefulness as a coffee substitute or extender and as forage for livestock.  Dried roots are still used in coffee in New Orleans.  C. intybus is sometimes grown as a salad green.  Curly endive is a related species of Cichorium.

Chicory along a roadside - photo by Marcia Morre

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Hello blog readers!  I have been absent for some weeks due to my daughter’s graduation from UIndy (hurrah!) and an invited speaking engagement at the Brooklyn Botanical Garden.  Now back to local flora.

Have you seen fallow farm fields of yellow flowers so dense they look like they must have been planted?  The flower is butterweed (Packera glabella, used to be call Senecio glabellus).  Other members of this genus are called ragworts.

Butterweed at Southwestway's Park

Butterweed fills an area so thoroughly that it looks like an invasive non-native but it is in fact a native – but invasive.  It is definitely on the increase in central Indiana and is showing up as a lawn weed on the Butler University campus.  Marcia Moore and I took these photos along the White River at Southwestways Park in Indianapolis this week.  We did not see this plant in the park when we inventoried the flora 8 years ago.

Butterweed’s striking yellow stands are beautiful.  It is a member of the aster or daisy family.  Both the disc and ray flowers are yellow.  Leaves are pinnately  divided (like a feather) and the stems are large and hollow, often with vertically running ridges.

Lots of yellow

It has little tuffs of hairs like dandelions that help spread the seeds around. It is a winter annual or biennial and seems to prefer moist soil.

I have read that no-till farming may be one of the reasons this plant is on the increase.  I do not know the origin of the common name but would like to hear any ideas.

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Beautiful redbuds

Redbud (Cercis canadensis) is in spectacular bloom this year. 

Redbud in a yard

Although it seems the common name should be pink or purple bud, I guess the flowers in bud are redder than when open in bloom.  I’ve always wondered how pioneers learned colors and kept them consistent before many folks had books in color or other ways to standardize.  Anyway, redbud is unusual in our area in that it is in the legume, the bean or pea, family and yet is it a small tree. 

Bean-shaped redbud flowers

A close look at the flowers shows the familiar bean flower shape and the seeds are borne in legume pods that split open along two sides. Black locust is another woody member of this family in our area.  Redbuds have cute hard-shaped leaves that come out after the flowers. 

Redbud leaves are heart-shaped

There is a very nice display of small redbuds in landscaping around Panera Bread at Glendale Mall here in Indy.  In my yard near Butler, redbud comes in on its own and grows quickly to reach flowering size within a few years.

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Silver maple flowers

Silver maple (Acer saccharinum) was in full bloom a few weeks ago.  All trees bloom.  We are sometimes unaware of this because forest trees are usually not as showy as dogwoods and Ohio buckeye.  Forest trees flower early, some as early as February.  They are wind pollinated, so flowers are mostly anthers that release pollen and stigmas that catch it.  No need for colorful petals.  The flowers are borne up in the branches and hard to see until you get an eye for them.

Counting on wind to make the connection is chancy, so lots of pollen is produced.  Tree pollen in the spring is a big source of hay-fever.

Silver maple flowers. Female cluster on top, male on the bottom

Flower clusters are either male or female on the same tree.  Male clusters tend to bloom earlier closer to the main trunk, with females out toward the tips, likely to increase the chances for outcrossing.

Silver maple is our most common street tree in Indianapolis.  They used to be favored because they grow quickly.  Because of this quick growth, they tend to be weak trees that are often brought down in ice or wind storms, so they have fallen out of favor. 

Silver maple has nice gray bark with a sculptural quality

In their natural habitat of riparian corridors along creeks and rivers, growing quickly to beat floods is an advantage. 

 I’m wondering if red maple gets its common name from its flowers.  They are striking red this year.  Silver maple must come from the silver undersurfaces of the leaves.  You can easily see these on a windy day.

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Flowers of harbinger-of-spring


Harbinger-of-spring (Erigenia bulbosa), aptly named, is one of our first native woodland spring wildflowers to bloom.  This tiny member of the carrot family can sometimes be found peeking above last year’s dried tree leaves through the snow in February.  I saw it blooming last Friday on the Butler campus. 


Nick Harby with Purdue University’s Kriebel Herbarium snapped this photo about a year ago near the entrance to Butler’s Holcomb Gardens.  Plants are blooming there now at the base of the giant beech tree about 30 feet past the entrance gate on the left, just off the road. 

Harbinger-of-spring in beech tree roots shot by Nick Harby




Some refer to the plant as salt-and-pepper due the blackish (more a dark purple it seemsto me) and white color pattern on the flowers.  Leaves come later.

Flowers of harbinger-of-spring

Early blooming plants have a strategy to get growing quickly in the spring.  Last time I wrote about the winter annual called whitlow grass.  It overwinters as a rosette of leaves that stay evergreen.  It can quickly send up a flowering stalk with just a few winter days.  Most early spring wildflowers have underground storage structures to provide energy to jump-start flowering without the need of current photosynthesis.  They are just like crocuses, tulips, and daffodils in this regard. 

Harbinger-of-spring’s tubers can be seen in this sheet from the Friesner Herbarium.

Another early flowerer, skunk cabbage, actually gives off heat to melt snow to allow the flowers to get serviced by pollinators.

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Plants blooming on Ground Hog Day, 2012

I looked for harbinger-of-spring (Erigenia bulbosa, aka salt and pepper) in the Butler University woods but couldn’t find it yet.  Some years it sticks flowers up through the snow around the last year’s decomposing tree leaves.  I did, however, find the reliable early February bloomer whitlow grass (Draba verna).

Rosettes of whitlow grass are the size of a quarter.

  This tiny mustard grows in a couple of places in sparse lawn on campus.  It is a native of Europe that I have read was used to treat inflammation of the toes or toenail fungus, whitlow, in England.  Maybe it was brought here intentionally.  It is a winter annual, germinating and forming a rosette of leaves in the fall and flowering in the early spring, setting seed and dying.  It persists through the summer as seed, starting the cycle again in the fall. 

USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York. Vol. 2: 148.

If you use a hand lens you can see the classic cruciform, or cross shaped arrangement of the 4 petals and two short, four long stamens found in the mustard family.

A speedwell was also blooming on Ground Hog Day this year in the warmth of the sunny base of the Science building at Butler University, Gallahue Hall.

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