Groundcovers, do they need to be green all the time?

As I think about the landscapes that I have idealized from an early age, they are green and full of life all year long.  But I grew up in an area that did not have four seasons and at a time when droughts and water management were not something that we worried about.  So the expectation of having some sort of green ground cover 365 days a year was not difficult to achieve.  Now after living in the Northern half of the US for 40 some years I have come to realize that having four seasons means that there is a good chunk of time when the plants in the landscape take a break and rest. 

Vinca minor is a widely used and invasive groundcover, originally from
central and southern Europe, that is often used where an evergreen carpet is desired.   

English ivy forms a dense evergreen cover that spreads by both
 runners and seeds.  It is particularly damaging when it is allowed to climb trees.

This brings up a question, does all the ground need to be covered all the time?  Yes, for protection from erosion, extreme temperature fluctuations and evaporation coverage is beneficial.  Groundcovers, both living and dead, also provide wildlife habitat.  There has been increasing awareness of the importance of  providing habitat for overwintering insects as they are critical sources of food for birds and other predators.

Alleghany spurge, Pachysandra procumbens, native to the mountains
of the Southeast, acts as a more naturalistic groundcover.

Does it need to be green all the time? No, not really.  But there is a desire among many for a lush green ground covering year around.  This desire is' might I say, for primarily aesthetic reasons.  To get this year-round green in temperate climates many folks are drawn to non-native species like Japanese pachysandra, English ivy, Vinca minor , yellow archangel (Lamiastrum galeobdolon), wintercreeper euonymus, mondo grass and lilyturf.  Most of these species are invasive in many parts of North America.

Here's my listing of the importance of having a ground cover, roughly in order of importance:

Minimize Erosion by holding soil against the forces of rain and wind;
Water management, by improving water infiltration and reducing evaporation;
Soil Health, by avoiding compaction, maintaining good aeration, moderation temperature and moisture extremes.  All these help maintain a healthy soil microbiota;
Maintain ecology by providing places for native insects to overwinter, less disturbance provides better survival rates for overwintering insects and nesting sites;
Weed management, its harder for seeds to geminate on shaded soil, in competition with established plants or where roots cannot take hold; and,
Aesthetics, create a visually pleasing composition.

As I alluded to above, the ground cover does not need to be green and growing year round.  In fact, depending on the climate and the environment the most appropriate ground cover may not be green at all.

In the majority of cases the material covering the ground will be some sort of plant material.  Having a actively growing root network under the soil to stabilize it and keep it biologically active is the ultimate goal. Where climate and conditions allow having a living mulch is an ideal solution for protecting the ground. The plants making up this living mulch need not be green though all four seasons.  They just need to continue to to hold the soil in place.  Green and actively growing on top is nice but not a year-round necessity.

The following are descriptions of how natural groundcovers function in three habitats that are similar to what you might encounter in a residential setting: Woodlands, Grasslands, and Deserts.

Mayapples, Podophyllum peltatum, provide a dense cover throughout
the spring as the forest canopy leafs out.  They hold the soil
with a wide spreading network of rhizomes.

Spring beauties are another spring ephemeral that are found on forest edges.

Woodlands: In Eastern deciduous forests the ground is covered year around by a layer of decomposing fallen leaves, natural compost.  Similarly, in coniferous forest there is a slowly decomposing layer of fallen needles.   Depending on the amount of light there is an understory of perennials and shrubs adapted to those conditions.  Where there are gaps in the canopy and accessible soil, new plants can get a start.  Depending on the composition of the seed bank these may be native or non-native species.  In a well balanced system the amount of undergrowth will be determined by the available resources.  Because of the way the available light changes through the year the nature of the ground cover plants also changes through the seasons.  In springtime the ground may be covered with ephemeral species like mayapples and Dutchman's breeches.  By summer these disappear and the ground plane is less densely covered with shade tolerant species like ferns and sedges and understory trees and shrubs.  Fall and winter feature the return of fall leaves which slowly decompose to replenish the soil with nutrients as well as serve as habitat for overwintering creatures.

Grasslands: In grasslands the winter ground cover consists of dead leaves and stalks from the past growing season and a network of crowns of the overwintering plants.  A healthy layer of this plant debris serves to protect the soil and fill the necessary roles of a ground cover.  The root networks of perennial grasses and forbs help to hold the soil.  Standing stalks of tall grasses and perennials form important habitat for some overwintering birds and insects.  Where the ground has been cleared by natural (fire) or unnatural (cutting and raking) processes, space is opened up for new plants to grow, both desirable and unwanted, depending on the seeds that are present.

Little bluestem, Schizachyrium scoparium, is a common
component of many eastern grasslands and dry meadows. 
Even after it dies back in winter it maintains its visual appeal.

Arid lands: In desert environments growth is limited by the availability of resources, particularly water.  Here you typically see plants growing much further apart because they are limited by the amount of available moisture. Root systems of perennial species tend to be much larger in order to access sufficient moisture for growth and survival.  Particularly in hot deserts most of the organic material that falls to the ground gets burned up and does not contribute to build organic material in the soil for the long term.  In these environments a natural ground cover would be inorganic in nature, rocks, stone and sand. While plants may not stabilize the soil on the surface, many have very wide spreading shallow roots systems adapted to harvest rainfall before it evaporates.   These wide systems can help to stabilize the soil, leading to less erosion.  Trying to maintain a green ground cover in a desert environment can be very resource demanding and not at all sustainable.

The ocotillo and purple-tinged prickly pear cactus each have shallow
wide-spreading roots to scavenge water thus limiting what else can grow nearby.

If green in winter is really what you need there are several native species here in the Mid-Atlantic that fit the bill.  Native (near)evergreens include, wintergreen (Gaultheria procumbens), green and gold (Chrysogonum virginianum), heuchera, tiarella, Alleghany spurge (Pachysandra procumbens), golden groundsel (Packera aurea), evergreen ferns (Christmas and intermediate wood ferns) and some sedges, like creeping sedge (Carex laxiculmis) are good for partly shaded locations.  For sunnier sites moss phlox (Phlox subulata), wild strawberry (Fragaria virginiana), common and creeping junipers, barren strawberry (Geum ternatum), as well as some grass-like plants like prickly bog sedge (Carex howei).  On most sites these plants will still be green through most of the winter, but they generally will not be lush with fresh foliage

Golden groundsel in winter.  The interconnected leaf rosettes
are held close to the soil.

In spring golden groundsel puts on fresh growth and sends up flowers.  

Getting into Spring: Wildflowers and managing Ticks

I have been fortunate not to have been bitten by any deer ticks so far.  One of the actions I am doing to keep that streak going is to put out homemade tick tubes twice a year.  These are paper tubes with several (5-8) cotton balls heavily treated with permethrin.  The idea is that mice will collect the cotton and use it in their nests.  There the permethrin will kill the ticks on the mice and break the deer tick life cycle early on.  Check out this link for more information.  We also spray our work clothes with a dilute solution of permethrin to deter ticks and especially chiggers.

I usually put out one batch of tubes in Mid-March, targeting a time when mice begin building nests.  I put them near brush piles and other places where mice might nest.  I use an orange flag to hold them in place and mark the location.  If there are still cotton balls left over I look for a different location to put the tube.  I also put out another set in the fall with the idea that mice will use them for their winter habitats.   

This springtime tube distribution also gets me out in the woods when the spring wildflowers are going to town.  This year has been more exciting than last.  It may have been the cold winter, or that my wife and I have been removing large quantities of garlic mustard, but the quantity of native wild flowers appears to be up. 

The flowers of Bloodroot only last a couple of days.

One plant that I missed entirely last year was Blootroot, Sanginaria canadensis.  In fact, I ordered a few of them to put into the garden, thinking I had none.  But an early March walk in the woods revealed that we have many of these plants.  One possible reason I missed seeing them before is that each plant has a very short blooming period, maybe 3-4 days, and I just wasn't in the right place at the right time.  

The three stem leaves on this Cutleaf Toothwort
are easy to see here.

Another early bloomer is the Cutleaf Toothwort, Dentaria laciniata.  The highly dissected leaves are a helpful clue to identifying this plant.  Also this Toothwort has three leaves on its flowering stalk, unlike its close relative D. diphylla, which has only two. These species have been moved over to the genus Cardamine and now it appears that the currently accepted name for the Cutleaf Toothwort is Cardamine concatenata.  

This was the only pink-tinged Dutchman's Breeches that I found.

One of the most common spring wildflowers in our woods is Dutchman's Breeches, Dicentra cucullaria.  Its flowers last longer than those of bloodroot.  Most of them are bright white.  However, a few plants have flowers that are pinkish.  Of the hundreds of plants in our woods I only found one with a pink coloration.  

Mayapples open like little umbrellas on the woodland floor.
These leaves will expand to 8 inches or more.

While they will not be blooming for a month or so, the leaves of Mayapple, Podophyllum peltatum, are appearing throughout the woodland areas.  Having a healthy layer of native ground covers like these should help in our battle against invasive species like garlic mustard and stiltgrass. 

I am trying a number of native ground covers like these under some pine trees
to replace the Vinca minor.

The Labrador Violet that I planted last season needed to be uncovered from a heavy layer of pine needles.  After a couple of days of exposure the leaves expanded and the first blooms opened up. 

I noticed that these blooms open the widest when the sun is at full strength.

In my last post I noted that there were many Spring Beauties and Spicebush beginning to bloom in the woodland areas.  I was asked whether these species would do well in full sun.  I do know of one or two Spicebushes that are growing in full sun in rather damp soil.  Then just the other day I noticed some Spring Beauties growing in the middle of the lawn in full sun.  So I guess the answer is yes; however, full sun is not their preferred habitat.

Needed to use my hat to get the flowers to be visible.

Last fall I planted several small Yellowroots, Xanthorhiza simplissima.  These plants flower just before the leaves open up.  It is very easy to miss these small maroon colored flowers.  The primary landscape use of Yellowroot is as a medium tall, fine textured ground cover.  

The pubescent flower stem is an identifying feature
of this species of Saxifage

My newest find while distributing the tick tubes was  Early Saxifrage, Micranthes virginensis.  These were growing at the base of a Beech tree mixed in with some white Spring Beauties.  The unique flower growing out of a basal rosette of bluntly lobed leaves stood out as something different from the other flowers in the area. 

The last wildflower that I spotted last week was a Dogtooth Violet, Erythronium americanum, growing near our house.  I had seen some growing near a stream but I was surprised to find this in an upland area.  It may have been planted there by the previous owner.  My wife spotted this as she was pulling out Garlic Mustard.  It is most easily recognized by the mottled foliage.  The flower is only present for a relatively short amount of time.

This Trout Lily started blooming about 2 weeks after the Bloodroot.  
This flower is on the pale side for E. americanum, it could be different species or a variation. (On looking more carefully, this is E. albidium, based on the spreading tip of the style; it's united in E. americanum.)

Spring is making an Appearance

With all the snow and low temperatures the Winter of 2013-14 seemed like it would never end.  But looking back at photos from this time last year, native plant growth is only a week or so behind 2013.  I almost did not venture out into the woods for an informal survey, but I'm glad I did.  While only a few native species were in bloom, many have broken ground and are forming flower buds.  Here are some photos of the highlights.

When walking through the woods, it pays to look up once in a while.

Many of the native spring wild flowers most active while the tree canopy is open.  Now they have have enough light to photosynthesize and store up energy.  Once the trees leaf out there is not enough light for these plants to continue to grow so many of them shut down for the summer.  These plants are known as the spring ephemerals.  

The first plants I noticed were the Virginia Bluebells, Mertensia virginica.  These first appear as purplish-gray buds through the leaf litter.  If last year is a guide they should be blooming in about 2 weeks.

As the leaves of these Virginia Bluebells mature they lose the purplish blush.

I was surprised to see the Spring Beauties in bloom.  There are only a few of them now.  Their number should continue to increase into May.  These grow from corms, so technically they are native bulbs.  If I happen to dig up any later this spring I will move them up into the bulb gardens closer to the house.  

These blooms are mostly white, pinkish ones appear later in the season.

The finely divided foliage of Dutchman's Breeches, Dicentra cucullaria, is also making an appearance.  I don't know if this species can be distinguished from Squirrel Corn, D. canadensis, just by the foliage.  I am making the assignment based on only seeing the former species last year.

The new foliage of all 3 eastern Dicentra species is very similar.
Off to the right are some leaves from Spring Beauties.

White Avens, Geum canadense, will bloom until later in the summer, but it is producing fresh foliage now.  It is recognizable by its deeply divided gray-green foliage.

One of the large basal leaves of White Avens  is at the lower right in the photo above.  

I saw a lot of leaves of Toothwort, Cardamine diphylla, and a few with flower buds. I also saw some leaves of cut-leaved Toothwort, C. laciniata.  These have similar coloration, but the leaves are deeply cut into five or more fingers.  These species were formally classified in the genus Dentaria.

You can see a mauve-colored flower stalk just left of center, above.

I purchased a couple of Golden Ragwort, Packera aurea, at a native plant sale last fall.  You can see that they over wintered well and it looks like they have already begun to spread.

Golden Ragwort should produce yellow daisy-like flowers on
long stems through spring and summer.

It's amazing that these little flowers will go on
to produce a couple of hazelnuts

The new growth was not limited to the perennials.  The shrubs are also beginning to bloom.  I got this American Hazelnut, Corylus americana, last fall.  It was bearing several nut clusters which grew to maturity last season.  This spring I only noticed the small red female flowers.  There were no male catkins on the shrub.  I don't know if their absence is due to the cold, or the deer.

I would have missed seeing the buds forming on this Yellowroot, Xanthorhiza simplicissima, if I had not remembered where it was planted.  The tops of the plant had been 'cut' back a bit.  Again, I don't know if this was from frost damage or deer browse.  

The flower buds of Spicebush, Lindera benzoin, are about to burst.  The flowering time of Spicebush is similar to Forsythia, but the color of the Spicebush is much more delicate.  In a week or so this area will be in a yellow haze of Spicebush flowers.  

Close examination of a Spicebush branch shows that the flower buds occur in pairs.
This helps with plant ID.

 All the new activity in the woods was not limited to the plants.  A small red speck racing along a a branch caught my attention.  It measured about 1/4 inch long and is 8 legged, like a spider.  Comparing images on a Google search for 'little red spider' led me to tentatively identify this as a Velvet Mite.  This is a predatory species feeding primarily on Arthropods.

This looks like it could be a Red Velvet Mite.  It moved very quickly for an insect so small.

More Maryland Wildflowers - 2nd Week of April

Deciding which native plant to use in a developed suburban landscape was fairly straightforward for me.  I could choose the plants I wanted without regard for to how it would impact the surrounding plant communities.  [Re]-introduction of nearly any native species into a sea of Euonymus and Barberries and the like would be a step in the right direction.

Now that I am working in a rural landscape I am becoming more sensitive to how my new plantings will affect the existing plant and animal communities.  I am cautious about introducing species that don't belong, native or not.  One very helpful resource for me is Native Plants for Wildlife Habitat and Conservation Landscaping Chesapeake Bay Watershed from the US Fish and Wildlife Service.  This publication lists many native species found in the Chesapeake watershed including their native ecoregion (Mountain, Piedmont or Coastal) and state where each is found.  

As a designer I also want to insert some visual effects with form and color.  This may require broadening the plant palette, drawing in materials from other areas and even a few well behaved non-native plants to achieve a particular aesthetic effect.  In general I will utilize a wider variety of plants in the immediate vicinity of a house or other man-made feature.  As I move out to the edges of a property I narrow the plant selection to the regionally native species.  I try to avoid introducing any species that don't naturally belong there.  

So before I get too far in planning and planting new native gardens I need to do some surveys of what is already present.  This (finally) brings me to the topic of what I found growing during the second week of April.  The tree canopy was still pretty open and the woodland floor was really greening up.




The first thing that really hit me was the masses of Virginia Bluebells that were coming into bloom.  These started coming up about a month ago.  Some had purple tinged foliage that has since turned green.



I was very pleased to see large masses of Mayapples coming up, especially I had just bought a half dozen to plant along the driveway.  These look somewhat alien when they first break ground.  They have a large white flower that stays just under the leaf.  

Mayapple leaves open up like umbrellas, 6-8 inches across.  

Once leafed out Spicebush can still be identified by the spicy scent of its bark.

The number of Spring Beauties has finally peaked,
now the blooms remain only in the shadier spots.
Note the garlic mustard off to the right.

Spicebush was another plant that I had just purchased to add to driveway area.  I was very happy to see a large mass of these growing near the creek.  The little flower clusters add an ethereal yellow haze to the scene.  These are not as garish as the Forsythia that are also in full bloom at this time.  






The Spring Beauties, Claytonia virginica, are continuing to come out - now the ground is sprinkled with the pale pink blooms.  The Dutchman's Breeches, Dicentra cucullaria, have also come into fuller bloom.  Some are white and others have a yellowish cast.  

Flowers started out a pale green
before opening up and turning white.

In with the Dutchman's Breeches is a plant with similar finely divided foliage, but this one had tubular yellow flowers.  It turns out that this is Yellow Fumewort, Corydalis flavula.  This native annual is 4-12 inches tall and has glaucous green foliage similar to other Corydalis.  I had never seen this before and was suspicious that it may some of the non-native Yellow Corydalis (C. lutea) that escaped from a garden.  The distinguishing feature from other yellow Corydalis (C. aurea and lutea) is that the upper lip of the flower is toothed.  This species is rare in New England, but not uncommon further south and west.

This winter annual was probably among the
early foliage seen back in January

The upper lip of the flower is toothed.  Also,
 seed pods are visible just below the flower on the left.

Should be getting some yellow flowers from these Trout Lilies in a couple of weeks.
If they are white, then these would be White Trout Lily, E. albidum.

Down in the leaf litter I noticed the spotted leaves of Trout Lily, Erythronium.  No blooms or buds were evident at this time, so I will need to get back down to these is a week or so to catch them in bloom.  As I was climbing back up away from the stream I noticed that the Toothwort were finally in bloom.  The dangling white flowers are not spectacular on their own, but they complement the other ephemerals. The Woodland Phlox, Phlox divaricata, are putting up flower buds, but I did not see any in bloom.  Back up on the lawn I am seeing Common Blue Violet, Viola papilionacea, complemented by the yellow flowers of Rough Cinquefoil, Potentilla norvegica.  Oops, these are actually the non-native Indian Strawberry, Duchesnea indica, see the comments below.

Each flower stalk of these toothworts has a pair
of deeply tri-lobed leaves, hence the epithet  'diphylla'.

Woodland Phlox has formed it flower buds.  Opps, this is actually Cardamine laciniata.

Common Blue Violet has hairless flower stalks,
otherwise this could be Woolly Blue Violet, V. sororia.

Unlike other weedy Cinquifoils, Rough Cinquifoil has
trilobed leaves and relatively large blunt-tipped flowers.  However, this is actually
Indian Strawberry, Duchesnea indica. with larger flowers than the Cinquifoil
and later a red berry.

Along with all of these natives there is a large population of garlic mustard that are beginning to bloom now.  Removing these will be a long and tedious process.  I have put a supply of black trash bags around the property to collect these.  In areas where the soil is moist it is possible to get most of the root out by gently pulling the plant by its crown.  Garlic mustard has a lot of stored energy in its root and may be able to set seed even though it has been pulled out of the ground.  A good practice is to bag them up and let them bake in the sun for a while before sending them to the landfill.  Garlic mustard should not be put into your compost. However, it is edible and you can make a decent pesto from it.

Spring Wildflowers: Texas vs Maryland

Two weeds ago we made a trip to Texas to visit family.  The end of March is the beginning of Texas wildflower season.  We flew into Austin then drove up to the Ft. Worth area.  You could see that Austin was really coming into bloom.  As we drove northward along I-35 the number of Bluebonnents along the highway dropped off considerably.

Even at 75 mph you can appreciate Texas Bluebonnets

One thing about seeing wildflowers in Texas is that they come in big patches.  Much of this is due to the efforts of Lady Bird Johnson with the Texas Highway Department to create and preserve wildflower habitats along the highways.

View of Courtyard at the Wildflower Center in Austin, TX

When we got back down to Austin we paid a visit to the Wildflower Center.  Here we saw many of the wildflowers we saw along the highways, but this time with handy name tags.

Texas Bluebonnets at low speed.

There are about 50 species and subspecies of
Indian Paintbrush (Castilleja).  I don't know
them well enough to tell them apart.

I've been looking for seeds for Groundsel.  This looks like it would be a nice addition
to a low-growing meadow/lawn alternative.  It has bright yellow flowers in spring
emanating from a basal rosette of leaves.

This Blackfoot Daisy is found on dry well drained soils.
I was interested in growing this plant, but the Northeast
does not provide the best conditions.

This little Prairie Verbena was all by itself, but it is known to
grow in large swaths, turning the ground purple. 

The narrow bronzy-green leaves of this Spring Beauty
blend into the leaf litter.

On our return to Maryland, the landscape was just beginning to turn from brown to spring green.  However, there were no massive swaths of color as we had witnessed the day before.  Inspired by all those Texas flowers I took a walk through the woods and found a few subtle surprises.  There were little pinkish white flowers along the edge of the woods.  These turned out to be Spring Beauties, Claytonia virginica.  This ephemeral perennial blooms in early spring, then essentially disappears after setting seed.



Further into the woods I found the masses of Toothwort continuing to expand.  The buds still have not opened, but they are nearly ready.

It's early April and these Toothwort are nearly ready to bloom.

The latest find was masses of finely cut foliage indicative of the genus Dicentra.  I searched around for a while and found one clump with developing flowers.  I'm pretty sure that these are D. cucullaria, Dutchman's Breeches.  I will keep a watch out for other family members, like Squirrel Corn (D. canadensis) and Wild Bleeding Heart (D. eximia).  These are most easily distinguished by the shapes and colors of their flowers.

When the flowers of Dutchman's Breeches are fully developed
they look somewhat like upside down pantaloons.

  

 I'm not keeping score, but the spring wildflowers in Texas are a grand sight to behold, but when the early summer temperatures creep into the 100's they will disappear.  In the Northeast the ephemerals will also slowly fade from view, but this will be due to the developing shade of the woodland canopy rather than the heat and dryness.  No matter where you live you've got to get out and appreciate that winter is coming to an end.