Native Annuals revisited

The ubiquitous black-eyed Susan, Rubeckia hirta,
can bloom in its first season from seed
but may persist for up to 3 years.

A little over 10 years ago I kicked off this blog with an introduction to the idea of using native annuals in the home landscape.  I thought it was time to revisit this theme and add a little more detail with a focus on native annuals and biennials that can be used in the Mid-Atlantic garden.

While there is a growing interest in native trees, shrubs and herbaceous perennials there are very few native annuals promoted for landscape use in native landscape designs.  This lack of focus is due in large part because the longer-lived species can be counted on year after year to uphold the integrity of the design.  When included in a design, conventional annuals are often used as temporary accent pieces, just to add interest or fill a gap in the permanent landscape. 

In general, many of the annuals used in designed landscapes and home gardening are of exotic origin and have been further improved horticulturally for maximum visual affect.  These plants and methods are not bad or evil; they are just a several steps away from what would be considered natural to a given area.  While beautiful, these plants lack local character, certainly on a regional, if not continental scale.  To the extent that they are different from the local flora, they may not provide the same ecological value, such as food and shelter for wildlife in the area, as native species do. 

In contrast, native annuals may function more as perennials.  Those that are adapted to the local environment will die back after a season or two, but they will maintain a presence in the garden, by reseeding, though not necessarily in the same location.   For some people, this may be a problem since the plants will move around, disrupting the design.  Others would consider this as a natural phenomenon and appreciate how plants are able to find their proper niche.  The ideal native annual could be considered as a plant that develops quickly with more flowers, a longer flowering cycle than perennials, and that reseeds but is not invasive.

Plant Selection for the Mid-Atlantic

To generate my initial list of Mid-Atlantic annuals and biennials I used the USDA Plants database.  This database contains a listing of all plants identified as growing wild in the United States.  It does not, however, distinguish whether the plants in a location are indigenous or have escaped cultivation. Using the 'Advanced Search' function I first selected North American native species. Then I selected NJ, PA, MD, WV and VA as my Mid-Atlantic States.  For duration I selected annual and biennial and I selected 'forb' for plant type.  This resulted in a list of over 700 taxa.  This list of plant names included some duplication since varieties and sub-species are listed in addition to the species.  This database has since been revised but you can get similar results for your region using its new “Characteristics Search” feature.  Alternatively you can use the Wildflower Center’s combination plant search function on their database, but there you would be doing one state at a time.

Here are three short-lived Mid-Atlantic natives,
spotted beebalm over growing a patch of
American pennyroyal and
 backed up with black-eyed Susans.

Next, I scanned the list for species that I was familiar with that, in my opinion, had some garden value.  The attributes I considered included form, appearance of foliage or flower, scent of flower or foliage, or value to wildlife.  I came up with a list of over 40 species that I have or would like to have in my gardens.  These criteria are of course arbitrary in the sense that I am looking at features from a human perspective.  In reality each of these species has evolved to fill an ecological niche and, as such, has a real value in their natural home.  Most gardens, however, are created and curated by humans, and are not complete, natural ecosystems.  This is especially the case in urban and suburban settings where soils, water courses and wildlife corridors have been disrupted; although, we can aspire to create naturalistic areas where some semblance of a natural ecosystem can catch hold, particularly with the use of native plant species.

The Plants

Here’s a partial listing of the native annuals and biennials grouped according to their garden function.

Big Plants

Bearded beggarticks can grow from seed to about
5' tall in a season.  Bloom time is in late summer.

Despite their short life times some native annuals and particularly biennials can grow quite large, 4-6 feet tall.  These plants are best located in the background or in a larger format setting.

Bearded beggarticks (Bidens aristosa), American bellflower (Campanulastrum americanum), tall thistle (Cirsium altissimum), biennial gaura (Oenothera gaura, formerly Gaura biennis), jewelweed (Impatiens capensis), and evening primrose (Oenothera biennis).

Showy Plants

These species are of more manageable size and have good sized and/or showy flowers.

Climbing fumitory (Adlumia fungosa), partridge pea (Chamaecrista fasciculata and C. nictitans), plains coreopsis (Coreopsis tinctoria), Corydalis sempervirens, fleabanes (Erigeron annuus and E. philadelphicus), firewheel (Gaillardia pulchella), annual sunflower (Helianthus annus), cucmberleaf sunflower (Helianthus debilis), sneezeweed (Helenium amarum), standing cypress (Ipomosis rubra), spotted beebalm (Monarda punctata), sweet everlasting (Pseudognaphalium obtussifolium), black-eyed Susan (Rudbeckia hirta), clasping Venus looking glass (Triodanis perfoliata), and blue vervain (Verbena hastata).

Partridge pea returns reliably from seed
each year if open soil is available

Philadelphia fleabane is a prolific reseeder and
can grow anywhere there is an opening, such as a thin
 lawn.  Commonly grows as a biennial in my yard.

 Fillers

These plants will fill in space and while each has some interesting features, will not steal the show.

Hog peanut (Amphicarpaea bracteata), yellow corydalis (Corydalis flavula), American pennyroyal (Hedeoma pulegioides), Indian tobacco (Lobelia inflata), clearweed (Pilea pumila), red-whisker clammyweed (Polanisia dodecandra), Pennsylvania smartweed (Polygonum pensylvanicum), field pansy (Viola bicolor), and common blue violet (V. sororia).

American pennyroyal has very small flowers
but produces a strong minty scent when disturbed. 
Its tiny seeds can find their way into the smallest cracks.

Special Requirements.  

Most native annuals owe their long-term success to being adapted to some form of disturbance which makes it difficult for long-lived plants to get established.  Some species are adapted to very special conditions.  One common example is jewelweed (Impatens capensis).  This annual can grow quite large and sports distinctive orange flowers but it needs very wet soils to survive. 

Some interesting native annuals are hemiparasitic, their roots tap into nearby plants to help them develop fully.  Two examples are the False foxgloves, such as fernleaf false foxglove (Aureolaria pedicularia), which are parasitic on oaks, and Scarlet Indian paintbrush, (Castilleja coccinea), which grows with assistance from the roots of grasses. 

Winter annuals are a group of plants that have adapted their life cycles to avoid the heat and dryness of summer, or competition for sun light in a wooded setting, by doing most of their growth from fall into springtime, when light and moisture are more plentiful.

Spring blue-eyed Mary germinates in the fall and
blooms in early spring.  It is often found growing
under deciduous trees.

Some winter annuals found in the Mid-Atlantic include: Spring blue-eyed Mary, (Collinsia verna), Yellow fumewort (Corydalis flavula), Old field Toadflax (Nuttallanthus canadensis), Fernleaf phacelia (Phacelia bipinnatifida), Miami mist (Phacelia purshii), and Field pansy (Viola bicolor).

One trick with growing winter annuals is that you need to avoid pulling them out while you are cleaning up flower beds in the early spring. 

This clasping Venus looking glass came up on its
 own and bloomed in early June.  To encourage its
 return I avoided mowing the area so that it could
 set seed, but it will need open soil the following
 year so that it can grow.

A few of these species are commercially available as potted plants right now.  Others may be had by getting seed from native plant suppliers.  For others, these plants may occur naturally on your site and one just needs to be observant when they show up and then to take care that they are able to develop and set seed to create a new generation.

 

New Seedlings and Sprouts

While a few established plants did not make it through this past winter most did and are performing quite well now.   A number of plants that I put in last fall which I had written off as lost 'suddenly' reappeared in the middle of May.  These include a Passion Vine,  some New York fern and False Goatsbeard (Astilbe biternata).  It was very fortunate that I left the plant tags in the ground otherwise I may have totally missed these late arrivals and possibly removed them as weeds or planted something else on top of them.   The False Goatsbeard is an excellent example.  This was a new plant for me so I did not know when it would resprout or what it would look like.  As the photo shows the new shoot could easily be mistaken for a dead twig.  Now that it has leafed out it looks like what I would expect for and Astilbe.

The new shoot comes up reddish-brown with tightly curled leaves.

Astilbe biternata is the only North American species of Astilbe.  It grows to over 3' tall.

The intensity of the red markings on the leaves is variable in the wild type plants

I have mentioned many times before that we are on a mission to remove the Garlic Mustard from our property.  In addition to improving the biodiversity it is giving us the opportunity to closely observe the other plants that were growing under the mustard canopy.  The other day after pulling some garlic mustard I found a patch of Jumpseed, Persicaria virginiana, (formerly Polygonum virginiana) that was growing in an unmanaged area.  I wanted to compare this to some red-flowered Jumpseed that I got from a nearby nursery.  

These Jumpseed from a nursery have a similar number of leaf veins,
but the shapes of its leaves is variable.

 Because most Jumpseed blooms with whitish flowers I was uncertain whether the red flowered plants were North American (var. virginiana f. rubra) or from an Asian species (var. filiformis) which normally has red flowers.  These varieties have different leaf shapes and number of veins on the leaf.  See this link for the original publication.  The characteristic leaf shape for the Asian species is obovate with an attenuate or cunnate base.  The nursery-grown plants have similar number of veins as the wild type (5-9 pairs), but the leaf shape is variable with a single plant having leaf shapes that match either species description.  Bottom line... I'm just not sure.

No garlic mustard in these Mayapples, but there
was woodland phlox and some galium species mixed in.

Another thing we noticed was that there was a large patch of Mayapples (Podophyllum peltatum) that was nearly devoid of garlic mustard.  I don't know if the Mayapples are actively defending against garlic mustard invasion or if this area has just not been invaded yet.  It does support the practice of having a good dense ground cover to shade out/exclude invasive species.  

Seedlings

I am seeing seedlings returning from 2 native annuals that I set out last year.  I am finding large masses of American Pennyroyal, Hedoma pulegioides,  near where I had planted them last year.  The seed that I sowed last spring did not germinate well last year (only 1 or 2  plants).  But seeds that had over-wintered are germinating like gang busters.  So despite what the seed packet says, some cold, moist stratification or fall planting of this species gives much better results.  I am encouraging these in my vegetable garden because they are reported to repel crawling insects due to the strong aromatic scent.  I am hope that it will have a similar effect on mammals as well.

 

These seedlings look similar to those of some Salvia species;
however, they can be distinguished by their strong aromatic scent even at this age.

The other annual that is coming back is Partridge Pea, Chamaecrista fasciculata.  Last year I started most of these indoors after  2 weeks cold, moist stratification and pretreatment with an rhizobactrium innoculant.   These germinated quite well both indoors and out.  This spring I am seeing many new seedlings near to their parent plants. 

The leaflets of Partridge Pea will fold up at night and when briskly jostled.

These blooms have just opened, the white petals
doubled in length a couple of days later.

As I was coming back from pulling more garlic mustard I stumbled upon another plant that I did not see last year.  I believed that it was Robin's Plantain, Erigeron pulchellus, because of the larger flowers and the spatulate basal leaves.  On digging a little deeper I realized that this was Common Fleabane, E. philadelphicus.  This species is indicated by the clasping leaves on the flower stalk. While not a beautiful garden plant is a pleasant surprise in the woods.  Most of my plants are actually growing on the path on the more compacted soil.  Perhaps I didn't see them last year because they had gotten trampled before they could bloom.

Just a note on the invasives front:  The garlic mustard is starting to go to seed now (late May), so we are trying to bag it up right away; also Mile-a-minute vine is starting to grow and the stilt grass is about an inch tall now.  It is really best to pull the mile-a-minute now before the thorns develop later in the season.