Plant Communities

A native plant by itself is not a native plant; it is “a plant”.  Native plants live in natural communities that are defined by their location aspects such as elevation, landforms, moisture level, geological characteristics, soils and are even influenced by the hand of humans over the last centuries.  While we can and do enjoy them in our gardens, understanding and appreciating their role in a community is often the basis for becoming a better advocate for habitat conservation.

Magnolia grandiflora

Southern Magnolia (Magnolia grandiflora) is an example of a plant that is native to the southeastern United States but which is used in landscapes in whatever areas are warm enough to support it.  I was recently vacationing in the San Francisco area and found it used quite often there.




I recently read Timothy Spira’s book “Wildflowers and Plant Communities of the Southern Appalachian Mountains and Piedmont” and learned a lot about 21 different plant communities in this particular region (which includes Atlanta). I highly recommend the book and hope to present here some of the things that I learned from it. This is a recent book, published in early 2011.

The region covered in the book extends from northern Virginia, a sliver of West Virginia, a slightly larger sliver of Tennessee, most of North Carolina, South Carolina, the northern half of Georgia and a small area of east/central Alabama. The area known as the Coastal Plain (the eastern portions of Virginia, NC, SC and the southern half of Georgia in this case) is not included and has its own very unique and diverse plant communities.  This book covers the 21 major plant communities found in the southern Applachian mountain and piedmont regions of the southeastern United States.

Twenty-one sounds like a lot of unique communities, doesn’t it?  It can be a little simpler if I list the high level categories:

In the mountains there are 4 categories: High-elevation communities (6 of those), Low-elevation moist to wet communities (5), Low-elevation dry communities (2).  In the piedmont (the author reminds us that “piedmont” literally means “foot of the mountains” – I love that!) there 3 categories: Moist to wet communities (3), Dry communities (3), and Roadside and Field.

The book includes some beautiful pictures and in-depth plant profiles so that it also serves as a field guide.  Before one gets into descriptions of plants, however, the author lays the groundwork for understanding how these communities have come to be.  He provides good background on factors as far back as when and how the mountains formed as well as the role that climate played in altering habitats and allowing species to expand or contract their range.  More recent factors include the effects of human activities and invasive species.

This area of the United States is incredibly diverse – according to the author: “the southern Appalachians support more tree species than any other area of comparable size in North America”.  In general the area is considered to be a temperate deciduous forest – or would have been without human intervention.  There are some particular areas that are not a forest, and these areas serve to increase the diversity of the plants even more.

The picture here was taken on the Shirley Miller Wildflower Trail in the area known as The Pocket at Pigeon Mountain (Walker County, Georgia).  The trail winds through a rich cove forest community.

Ferns, Trillium and dwarf Iris cristata on the Shirley Miller Wildflower Trail

The details provided in the description of the region covered by the book are fascinating.  For example, the region has 3 national parks and 6 national forests; together these areas have the greatest concentration of public land in the eastern United States.  As you read more about the wonderful habitat these areas protect, one is grateful that these areas have been conserved.  However, as you may know, imported diseases have devastated many of the trees in the area: American chestnut (chestnut blight), Fraser fir (balsam woolly adelgid), and Canada and Carolina hemlocks (hemlock woolly adelgid) are once dominant tree species that have been or are in the process of being destroyed.  The plant communities with hemlocks (Tsuga spp.) are changing right before our eyes as the woolly adelgid spreads.  Our increased understanding of these communities affords us a chance to provide some measure of protection here and in yet unaffected areas as we recognize more the importance of conservation.

Ok, that pretty much covers Part 1 of the book.  The remaining parts are:

Part 2: a pictorial representation of each of the 21 communities.  These collections give you a preview of the plants you might find.  A sample group of plants is shown to represent each of the 21 communities:

Spruce-Fir Forest (Mountains)

Grassy Bald (Mountains)

Heath Bald (Mountains)

High-Elevation Rock Outcrop (Mountains)

High-Elevation Red Oak Forest (Mountains)

Northern Hardwood Forest (Mountains)

Rich Cove Forest (Mountains)

Acidic Cove Forest (Mountains)

Spray Cliff (Mountains)

Rocky Streamside (Mountains)

Mountain Bog (Mountains)

Chestnut Oak Forest (Mountains)

Pine-Oak-Heath (Mountains)

Forest Edge (Mountains)

River Bluff Forest (Piedmont)

Alluvial Forest (Piedmont)

Basic Mesic Forest (Piedmont)

Oak-Hickory Forest (Piedmont)

Xeric Hardpan Forest (Piedmont)

Granite Outcrop (Piedmont)

Roadside and Field (Piedmont)

The picture below is a "roadside and field" community near my house.  Roadsides can be tricky - sometimes they are full of invasive or naturalized plants - not natives much at all.  But this one is good: it has at least 3 different species of Eupatorium, at least 3 species of Goldenrod (Solidago), at least 3 species of grasses (and perhaps a couple of non-native ones), several different asters, blue curls (Trichostema dichotomum), and slender leaf false foxglove (Agalinis tenuifolia) - just discovered this morning! 

Part 3 provides detailed descriptions of each of the communities. These profiles include Distinguishing features, Vegetation overviews, Seasonal aspects, Distribution, Dynamics, Conservation aspects, Suggested reading references, and good lists of Trees, Shrubs, Herbaceous plants, and Rare plants.

Part 4 has detailed species profiles for the plants listed in Part 3. One feature that I particularly like is the “Ecology” section of the profile. This section provides some details not found in the usual plant guides.

The book finishes up with a Glossary, a list of recommended natural areas throughout the region (with descriptions of the exceptional features to be found in each), suggested books for further reading (which includes some of my favorites), an index of scientific names and a second index of common names.
 
The depth of information in this book is excellent, and it is presented at a level that can be used by all levels of naturalists.  Back to that Southern Magnolia - it's not listed in the book, by the way.  That plant is not indigenous (i.e., naturally found) in the Southern Appalachian Mountain or Piedmont communities.  You can expect to find it naturally in south Georgia - in the Coastal Plains communities.

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!

Lobelia – Jewel of the Late Summer Garden

The genus Lobelia is truly an all-American flower – there are species that bloom red, white and blue!  It is also a genus with wide adaptability that, in general, enjoys a moist area, but some species can adapt to drier conditions.  Most species flower best in full sun.

Lobelia cardinalis

Lobelia is part of the Campanulaceae family which is in the Bellflower family.  They share the trait of milky sap (pull a leaf off to see) with many other members of that family.  They have another unusual trait: they have resupinate flowers.  This means that their flowers are inverted – what appears to be the top of the flower is actually the bottom.  You can see in this picture that they have an “upper lip” of two petals and a “lower lip” of 3 petals.  In reality, the lip with 3 petals is the top of the flower which has been inverted 180 degrees.

Lobelia cardinalis

The blooms open from the bottom up, seeds forming in the lower capsules even as the plant is still blooming.

Lobelia cardinalis

The genus is named after the Belgian botanist Matthias de L’Obel (1538-1616).  While members of the Lobelia genus can be found in temperate regions worldwide (yes, there is a Chinese one!), the red-flowered species, Lobelia cardinalis, was found in North America in the early 1600’s.  Seeds of this beautiful flower were taken back to Europe in the mid-1620’s where it earned the common name Cardinal flower.  This species is one of the most cultivated members of this genus today.

Pink flowered forms like Lobelia x 'Ruby Slippers' are hybrids of L. cardinalis and L. siphilitica.

Ok, enough with this gorgeous red flower - I promised you red, white and blue and you shall have it! The white flowering forms include the annual species Lobelia inflata, otherwise know as Indian tobacco, although some plants appear to be a very pale blue. The species name comes from the inflated appearance of the seed capsule.

Lobelia spicata

Another white flowered species is the perennial Lobelia spicata, found in my area in fields and on roadsides.  The long slender raceme of flowers provides for a very long bloom period.  My pictures really do not do it justice - it is a very graceful plant.  This site has very good pictures.

Lobelia spicata

I collected some of the seed this year and hope to grow it for myself next year.

Lobelias in general do not have "pretty" foliage.  The leaves are usually rather coarse looking, often dull and sometimes with rough edges.  I caution those that grow it for the first time to expect a weedy-looking rosette of leaves at first and to be careful not to weed it out by accident.

Lobelia cardinalis rosette

Also, don't let leaves or mulch cover the rosette over the winter or the plant may die.

The blue species of Lobelia are quite spectacular in their own right.  The "Great Blue Lobelia" is Lobelia siphilitica and it is a tall and handsome plant.  It prefers moist places, and provides brilliant color to the mid-summer garden.  I do not have it myself; the pictures here are from the gardens of friends.

Lobelia siphilitica
photo by C. Lim

Lobelia siphilitica

I do have the later blooming blue species, Lobelia puberula.  This species can handle drier conditions; in fact, we have found it the most in a full-sun field on a particular construction site.  The species name "puberula" indicates that it has some fine hairs on parts of the plants, and they are visible even to the naked eye on the stem and leaves.  The common name is Downy Lobelia.  I find the bloom to be much softer in color and texture than the Great Blue.

Lobelia puberula

Lobelia puberula

Consider adding Lobelia to your plantings.  Come late summer, you will be very glad you did.

Ragweed, not Goldenrod, is the culprit!

When the season of Goldenrod begins - the clusters of tiny yellow flowers gradually appearing on roadsides, I am careful to point the plant out to people.  The reason I do this is because I know that a lot of people think that Goldenrod (Solidago spp.) is the cause of fall allergies.  They often exclaim “Oh, that stuff bothers my allergies!”  That is my cue to educate them about the true culprit: Ragweed.

Goldenrod, likely Solidago altissima

Ragweed (Ambrosia spp.) quietly appears on roadsides around the same time.  The most familiar one around here is an annual plant: Ambrosia artemisiifolia.  The foliage is deeply cut – many gardeners mistake it for a seedling of Cosmos sulphureus, the familiar orange garden Cosmos.  People who aren’t gardeners just overlook it.  Another member of the same family is giant ragweed, Ambrosia trifida.  Even though it is also an annual, it grows to be over 10 feet tall in one season!  

Ambrosia artemisiifolia

While Goldenrod has bright yellow flowers, Ragweed flowers are green. The color of the flowers allows Ragweed to continue to be overlooked and ignored – people don’t even realize it is blooming.  When the allergens take to the wind, and people look for something to blame, it is the Goldenrod flowers that they see.

Could it be that both flowers bother you?  After all, if they are both blooming then they must both be throwing their pollen around, right?  Actually, the ability of pollen to fly through the air is limited by its own weight.

Plants that cause allergies have very light, dry pollen, and those plants rely on the wind to carry their pollen to another plant (of the same kind).  Plants with lightweight pollen include: oaks, hickories, mulberries and pines (spring), grasses (summer and fall), and ragweed (late summer to fall).  In fact these plants have non-showy flowers without petals that are just made for wind-pollination.

Ragweed flowers open and releasing pollen

In the picture above you can see the flowers. They don't have any petals - this is all they will ever do in terms of blooming. They don't need petals to attract any insects as the wind facilitates their pollination; in fact, petals would only get in the way!  As I was taking this picture, numerous grains of pollen were released from the flowers each time that I moved the plant.

Plants that are insect-pollinated have heavy, sticky pollen that is not picked up by the wind.  These plants have showy flowers that attract pollinators like bees, wasps, butterflies and birds.  The pollen brushes onto the pollinator and is then carried to the next plant that the critter visits.  Goldenrod is just such a plant.

Goldenrod flowers (Solidago altissima)

So now you have a perfectly logical reason to help you remember that Goldenrod is not a bad guy.  As the roadsides light up with the showy, yellow flowers of our native Goldenrods this season, you can smile and enjoy the show instead of eyeing them with dread.