August, peak season for .... Stilt Grass 😒

As August settles in many of the landscape chores are on standby.  It's too hot and or dry to plant and mostly too late for pruning.  But it is prime season for pulling out Japanese stilt grass, Microstegium vimineum, and other invasive species before they start flowering and going to seed.  

Here's a shady hill side where I am pulling Japanese stilt grass. 
The right hand side is 'complete', but haven't started on the left. 
This is my third year of trying to manage this area.  There may
be fewer individual stilt grass plants, but they still cover the area.  

Actually I have been pulling up stilt grass as time allows since early July, but around here, August is when it puts on its growth spurt before starting to bloom.  Pulling is most effective when the ground is a little moist and this shallow rooted plant comes up easily.  Unfortunately it has been quite dry here again this year and the stilt grass stems are becoming brittle.  So rather than pulling up the entire plant, it breaks off leaving rooted portions close to the ground.  As I have written in earlier posts, stilt grass has flowers hidden in its stem (cleistogamous flowers) that will develop even if the upper parts of the plant are removed.  A single stilt grass plant forms roots at multiple nodes that are close to the soil, often extending 1-2 feet from its origin.

It is important to do one area really well, rather than pulling a little bit over a larger area.  By removing all of the offending plants in a small area, that area has the potential of becoming invasive free, requiring less attention in future years. (One still needs to monitor a cleared area to prevent reinfestation.)  If you only remove a portion of the invasive species it will continue producing a new crop of seeds and continuing the infestation.  In areas that used to take me over an hour to clear, I now only need about 20 minutes to clean up.

While pulling stilt grass is tedious it gives you the opportunity to get close to plants to identify what else is present.  This can reveal other plants you didn't know you had.  You can also find other undesirable species and get them out before they get established.

One relatively new invasive species to the Mid-Atlantic is wavy leaf basket grass, Oplishmenus hitrellus subsp. undulatifolius.  I have been finding increasing amounts of this each of the past three years.  It can form dense mats that exclude other species.  It bloom in mid summer to mid-fall.  I have left a large trash bag in the woods that I can put these in to minimize the chance to spreading any seed.

Wavy leaf basket grass can be recognized by its pointy leaves and
rippled texture (see arrow).  Like stilt grass it will root all along
the stem, making it a little trickier to remove.  

Another invasive that shows up later in summer is beefsteak plant or shiso, Perilla frutescens.  This exotic annual is originally from Asia where is it used as a culinary herb.  It is a member of the mint family and its leaves have a licorice-mint scent when rubbed.  It can displace native vegetation, particularly in moist locations.  Its leaves are toxic to wildlife, giving it a competitive advantage over native vegetation.

This beefsteak plant seedling could grow to several feet in height. 
It can be distinguished by its large deeply veined leaves and
its minty scent.  Leaves can take on a reddish cast as they age.

Some of the more interesting native species that I have uncovered while clearing out stilt grass include several species of tick trefoils (Desmodium sp.), a witch grass and at least one unfamiliar aster, which I flagged for future ID. Following are some photos of easily missed native species.

Clearweed is native annual usually found in shady, moist locations. 
It is a member of the nettle family, but has no spines.  It can be
recognized by its deeply veined leaves with rounded teeth (crenate)
on its margins.  Dense patches reappear every 2-3 years.

I usually find the showy tick trefoil growing in the midst of taller grasses. 
The egg-shaped leaflets are a clue to its ID.  In late summer
it blooms with panicles of 1/2 inch lavender-pink pea-like flowers.
[This may be a different species, possibly velvety tick-trefoil, D. viridiflorum]

Wild basil usually appears on the edges of taller grasses. 
The leaves are deeply veined and have a grayish
cast due to fine hairs.  The pinkish flowers are in dense heads
or in clusters on the upper leaf axils.  Note the silver-veined
 leaves to the lower right are from panicled tick trefoil, not stilt grass.

White grass is sometimes confused with Japanese stilt grass. 
It has a similar shade of green, but its leaves are longer
and lack the silvery midvein of stilt grass. It is found mostly
 in moist, shady locations but can be in drier areas as well.

These 'dead men's fingers' probably Xylaria polymorpha, is a fungus
that grows off of dead or dying wood.   In this case from the roots
of a former ash tree.  I spotted these in early July.

In addition to locating new plants I noticed a variety of insects that were new to me. I have found that the 'Seek' app is very useful in identifying many of the unknown plants and animals that I have encountered.

This 1/2 inch robber fly, Gray Goggle Eye, will perch on taller grasses
 and other plants while searching for prey.  It stayed in place long enough
for me to get a good photo to submit to the Seek app on my phone. 
It feeds on other flying  insects and is also known as a 'small gnat ogre'.

Some Forgotten Native Mints

The Mints, Lamiaceae, are a large family of plants with about 40 genera appearing in eastern North America.  Native species that we commonly think of used as landscape plants include Beebalms (Monarda), Mountain mints (Pycnanthemum), giant hyssop (Agastache), Salvias and Obedient plants (Physostegia).  There are also the non-native species commonly used a culinary herbs like  thyme, oregano and the spearmint.  Common attributes of mints include tubular bilabiate (having two lips) flowers usually occurring in whorls or dense spikes, square stems and often aromatic foliage.  I recently wrote about the mountain mints that I have been growing and it got me to thinking of some of the smaller and less common (in the garden) native mints.

Here you can see the dense flower cluster of wild basil.   Blooming
continues from these throughout the summer months.

One of the wild mints that always surprises me when I spot it in the meadow is wild basil, Clinopodium vulgare, (formerly Satureja vulgaris).  Although the leaves and flowers are essentially unscented, this is made up for by the  clusters of pink flowers appear scattered throughout the tall grasses.  The stems are not particularly stiff, but they lean up against the taller grasses and meadow perennials like ironweed and wingstem (Verbesina alternafolia) allowing the flowers to reach up to 3 or 4 feet into the meadow matrix.  My plants bloom sporadically throughout the summer months.  I've also seen this plant growing alone in shady sites.  Without taller plants to lean on it grows about a foot tall on lax stems.
  

Here is some wild basil that is growing in shade and had been surround, until recently,
by Japanese stiltgrass. Note how the stems are reachng out to find more light.

The native range of wild basil is from eastern Canada to Tennessee and North Carolina.  Outside of that area plants are likely introductions from Europe.  On-line suppliers of native seed include Toadshade Farm and Prairie Moon Nursery (as Satureja vulgaris).

Pictured here is self-heal blooming in mid-July.  The flowering
 stalk grows from about 4 inches to a foot in height.

Self-heal or Heal-all, Prunella vulgaris, is found throughout the Northern hemisphere.  The North American variety (var. lanceolata) has somewhat narrower leaves than its European relative, which is also found scattered through the eastern parts of North America.  This perennial overwinters as a low mat of leaves that push up flowering stalks, 6-10 inches in mid-summer.  In my opinion these wouldn't work as a ground cover on their own, since they are attractive for only a few weeks to a month in summer.  But they would be a useful component in a mixed ground cover including violets, low sedges, spring ephemerals and the like.  One year it was growing densely in the vegetable garden so I thought I would treat it as a green mulch around some tomatoes.  Turns out the tomatoes did not do well surrounded by self heal.  I guess that there was too much competition and the tomatoes lost out.  
This plant is edible and can be added to salads.  Among its uses as an herbal remedy treatment of wounds and infections of the throat.   It is attractive to bees and butterflies and is a host plant for the clouded sulfur butterfly.  Seeds are available from several sources found on-line.  To get the North American variety you may need to check  and verify with the supplier where the seed is from. 

Here is Meehan's mint (circled) growing in dry shade.  Also present here
 are Virginia creeper (good) and Vinca minor (bad).  

Meehan's mint, Meehania cordata, is native to the Appalachian Mountains from western Pennsylvania to Tennessee and North Carolina.  It grows well in shady moist areas as a trailing vine that roots where leaf nodes contact the soil.  It can also handle dry shade, though it will be less vigorous.  In general appearance it is similar to the weedy invasive, ground ivy, Glechoma hederacea.  Meehan's mint has slightly larger and stiffer foliage and has no scent when crushed, unlike ground ivy.  Under favorable conditions it blooms in late spring with clusters of  inch long lavender blue flowers held on 6 inch long stems.  In this respect the floral display of Meehan's mint surpasses that of ground ivy.  It is recommended as a native substitute for exotic ground covers like ajuga and lamiums.

Mine is growing in dry shade and has not bloomed yet.  Follow this link to see it in bloom. When getting it established one needs to be careful about not confusing it with other similar, but non-native species like ground ivy and ajugas.  You can find Meehan's mint at nurseries specializing in native species or on-line nurseries, such as Izel Plants.