Sunday, September 18, 2011

Flowers of the Fall Roadside

Hail to the flowers of the roadside – those unsung heroes of nectar and beauty.  “Nectar and beauty?”, you say.  The insects know what I mean.  If you were to stop your car and get out to observe these flowers, you would see that they are covered in insects: bees, wasps, flies, butterflies and even beetles.  Many of these plants have a structure (what you might think of an a “flower”) that is actually composed of many tiny flowers.  Look at this Eupatorium altissimum flower for example:

These are tiny flowers that are composed of even tinier disk flowers that all together make up what you might have considered “one” flower.  The whole group is called an inflorescence.  You can imagine how such a plant as this would be a veritable feast for a hungry insect.  Here is the whole plant as you might see it:

Tall thoroughwort, Eupatorium altissimum

These are just some of the flowering plants on the roadside right now (I won't mention Ragweed; by the way; if you haven't seen it already, be sure to check out my post about recognizing Ragweed and understanding it as the allergy culprit, not Goldenrod).

Plants with large, fluffy white/pink/mauve flower structures are probably in the Eupatorium genus or their close kin in the Eutrochium genus.  Common names include Joe Pye Weed (Eutrochium sp)., Boneset, Snakeroot, and Thoroughwort.

Eutrochium fistulosum

Eupatorium perfoliatum

A recent member of the Eupatorium family is now Conoclinium coelestinum, known as Blue Mist Flower and Hardy Ageratum.  You will often see this at older homes, especially in rural areas, and in roadside ditches.  This plant spreads readily by rhizomes underground and so was a favorite passalong plant as well as a very dependable perennial.  It is a gorgeous shade of blue and not so hard to control in the garden if you pay attention to it. 
Conoclinium coelestinum

A tall purple-flowering plant is Ironweed, Vernonia spp.  If you have ever tried to pick one with your bare hands, thinking you could just snap a bloom off, you understand how it got the name "Ironweed" - the stem is tough!  Seemingly tolerant of both moist and dry areas, this is strictly a back of the border plant in a garden setting.  I have seen certain species grow to over 10 feet tall.

Vernonia noveboracensis

A more petite purple plant is Liatris, known as Blazing Star.  The one that we find most often in the fall is Liatris pilosa which has a modest wand shaped bloom.  The color mixes nicely with the golden flowers of Solidago and Helianthus.  Blue Lobelia also has a similar wand shaped bloom spike.  My post on Lobelia provides more details and pictures.  I see both Liatris and blue Lobelia in old fields and power line easements.

Liatris pilosa

The yellow roadside flowers include the occasional Rudbeckia (Black-eyed Susan), the later blooming Helianthus, and a whole bunch of Goldenrods (Solidago).  You can read more about late summer yellow flowers in my earlier post.  I have Helianthus atrorubens blooming now; Helianthus angustifolius is just about to bloom on 8 foot stalks.  I'm expecting that to be spectacular.

Helianthus atrorubens

Goldenrods (Solidago spp.) can be found all over the roadside as well.  There are many different species, but I think the one most familiar to people in the metro Atlanta area would be tall Goldenrod, Solidago altissima. People often think that Goldenrod cause allergies with it's pollen.  That is not true and you can see my earlier post for the reason why it is not true.

Solidago altissima

Boltonia asteroides

White Aster-type flowers are just now emerging.  Several of the ones near me are Bushy Aster, Boltonia, and Calico Aster.  The purple asters will not bloom for another few weeks here.  Both Bushy Aster (Symphyotrichum dumosum) and Boltonia (Boltonia asteroides) are modest looking plants that explode into hundreds of tiny blooms in September and October.  White woods aster (Eurybia divaricata) is more modest but a treat to find when tucked in with a group of other plants.

Eurybia divaricata

All these plants aren’t just for nectar lovers.  Their leaves are munched by various caterpillars.  Those caterpillars are then food for birds.  Later the flowers turn into seeds and those also are food for birds and small mammals.  So appreciate these roadside flowers for all that they do in our environment - besides make us curious as we whiz by!


  1. Fall is definitely my favorite time of year for the roadside wildflowers, and with our recent rains, everything really is putting on a show now. It's impressive how many beautiful plants can grow with the neglect and abuse a roadside has to offer!

  2. We had tall thoroughwort when we lived in Maryland and it attracted the most amazing insects in late summer. Nice to see you have so much going on along the roadsides.