Thursday, July 31, 2014

Shawnee Hills Floodplain Forest


The Shawnee Hills Floodplain forest is one of the new exhibits along the Walk Across Kentucky.  Planted during the spring and summer of 2013, it has quickly become established with some exceptional native plants from western Kentucky.  Presently, this area is overflowing with blossoms and pollinators.  In particular, the cardinal flower (Lobelia cardinalis) and its pollinator, the ruby-throated hummingbird (Archilochus colubris) are a sight to see.  

This specific site is a low-lying depression planted as a grove of willow oak (Quercus phellos) in 1991.  The area sees a substantial amount of surface water collect and flow through during heavy rain events.  Because the canopy of the oaks was so dense, there was minimal vegetation on the ground, and as a result this site was prone to erosion.  What may seem to be a location unsuitable for gardening is actually an ecosystem that is quite common, especially in the Shawnee Hills region of Kentucky.  Often referred to as a floodplain forest, areas such as these typically contain hardwood trees such as the pre-existing willow oak grove at The Arboretum.  The plant community is adapted to wet soils, often deep shade, and extended periods of submersion.  

The stunning transformation of this exhibit in the past year is a testament of the dynamism of native plants when planted in favorable locations.  Not only does this highlight that there truly is a right plant for all locations, but it shows how quickly (and relatively simply) sites such as these can be established.

Here is a look back at the development of this exhibit:
'before'; a very dense grove of Quercus phellos, complemented by false indigo (Amorpha fruticosa - front left) and eastern gamagrass (Tripsacum dactyloides - front right)
Step 1. Allowing visitor access required some pruning of the oaks for clearance as well as a boardwalk, since the area is prone to flooding.  This boardwalk was part of an eagle scout project.
The completed boardwalk in autumn, 2012.  The oaks had recently dropped their leaves, but the absence of ground vegetation causes them to wash away during winter floods.
Spring 2013, the Native Plant Volunteer group begins initial planting of the Floodplain forest.  This included removal of hidden patches of purple wintercreeper (Euonymus fortunei), a significant invasive species.

Autumn, 2013.  Over 500 perennial plant plugs were planted over the course of the summer, including blue star, iris (4 species), spider lily, ferns (3 species), Lobelia (2 species), starry campion, wood poppy, Elymus (2 species), and many others.  Also planted were some shrubs and small trees, including hearts-a-burstin', wahoo, american snowbell, swamp holly, and ironwood.  A willow oak was removed in the center of the grove to allow some filtered sunlight to enter the garden.  The trunk and limbs of the tree were left to help prevent washouts and provide shelter for the turtles that nest here.

Winter, 2014.  The floods arrive.  During heavy rain events this area stays flooded for days at a time.  The new boardwalk allows access through the garden, and the newly established vegetation helped to control soil erosion 
Spring, 2014. After concentrating energy on root growth the previous year, the perennials exploded in 2014.  The blue stars, trillium, phlox, beardtongue, and iris were extremely floriferous in early spring.
Summer, 2014. (today) 
Lobelia inflata (left), Lobelia cardinalis (right).
Swamp milkweed in a sunny spot at the entrance to the boardwalk, just beginning to open.
This informational sign was designed by Arboretum intern and UK Landscape Architecture student Will Coleman, and installed on the edge of the boardwalk.
A look back towards the WAKY, cardinal flower in all directions.  A pair of hummingbirds were taking full advantage of the red flowers but moving too fast to photograph.

Thursday, July 3, 2014

Rubus odoratus (flowering raspberry)

When it comes to summer flowering shrubs, one of the hidden gems on The Walk Across Kentucky is flowering raspberry (Rubus odoratus L.).  Of course, all raspberries flower, but Rubus odoratus blossoms are particularly showy.  The 2” diameter flowers are fuchsia in color, and are borne on terminal panicles throughout the course of the summer.  A member of the rose family (Rosaceae), the flowers are very similar in appearance.

In Kentucky, Rubus odoratus is quite rare, found predominately in the Cumberland Mountain region, though it may grow as an escape further west.  Of ~9 species of Rubus native to Kentucky, R. odoratus is the only species with simple leaves.   The leaves are palmately lobed and get quite large, with a size and texture similar to Hydrangea quercifolia.  Another nice benefit of this raspberry (unlike many) – it is thornless!

Culturally, this species prefers slightly acid, well-drained soils in sun to partial shade.  Like most species of Rubus, R. odoratus is a colonial plant that will sucker and spread, and must be kept in check in certain garden situations.  Cultivated plants can benefit from rejuvenative pruning every few years, and this should be done shortly after they have finished flowering.  Mature plants will reach 6’ tall.  

There are 3 accessions of flowering raspberry on the Walk Across Kentucky, near the Trail of Pines in the Appalachian region.  Their flowers, fruit, and architecture provide food and shelter for wildlife throughout the year.  

WAKY Trail of Pines

Tuesday, June 10, 2014

Keep on Rocking in the Free World

In April, the Walk Across Kentucky received an exciting new addition to the Shawnee Hills region: 40,000 lbs of rock.  More specifically, the rocks were sandstone boulders, seven of which accounted for an entire flatbed truck-load.  This delivery was made possible by the College of Agriculture, Food and Environment, as well as our dear friend Neville Crawford, a volunteer from western Kentucky who sourced the boulders for us.

The original master plan for the Walk Across Kentucky called for the use of various geologic features from across the state, including glades, cliffs, and other outcroppings.  We are slowly implementing these features as time and funding allow, for they truly bring their own unique character to the physiographic regions.  

Our new sandstone boulders can be seen from inside the visitor center.  Due to their imposing size they have begun to serve as a beacon, luring visitors southward beyond the rose garden.  It was no small feat moving and placing these boulders, the largest of which has a mass of nearly 5 tons.  We believe these rocks were formed over 400 million years ago when Kentucky was rising out of the ocean.  These sandstone monuments will become part of a future garden in the Shawnee Hills region, and surely last for many years to come.  

Here are a few images of the 200 mile journey from Mclean County to Lexington:

Mclean Co. Stones are assembled for loading.
Mclean Co.  Flatbed truck is fully loaded
Arboretum parking lot.  Stones are moved one at a time to the WAKY.
Shawnee Hills Region of WAKY.  Stones installed
View northward toward the Dorotha Smith Oatts Visitor Center
'Rock #1' in situ Mclean Co.
'Rock #1' ex situ and rotated 90 degrees
stones in the meadow

Even more recently, we had two other additions to the WAKY collections of the non-photosynthetic variety.  These installations were made possible by a donor in Jessamine County who allowed us to collect local limestone rocks from an excavation project.  These stones are far older than the sandstone, as they were formed when Kentucky was still underwater.  It is exciting to be able to display more of Kentucky's diverse geology, for it is geology that has played a major part in defining physiographic regions and plant communities across the state.

Here are the other two new installations, which should change dramatically as plants are added in the coming weeks:  
Bluegrass Scree Garden (above).  Limestone fragments form a skirt around a young Gleditsia triacanthos.  This area is well suited for plants that require dry soil and full sun.  Expect to see Opuntia, Manfreda, Yucca, and others planted here.

Bluegrass Fern Garden (below).  This enlarged sinkhole is the direct opposite of the scree bed, for it has moist soils in full shade.  Limestone was used to form artificial ledges, outcroppings, and a staircase to lead visitors into the pit.  This shady damp site has been planted with Hydrophyllum, Polymnia, and Elymus, and will be the site of a future bluegrass fern collection.  The limestone staircase can be accessed from a new mulched pathway that leads through a dense planting of maple, oak, and buckeyes.

Tuesday, May 20, 2014

A Tale of Two Citifications

Where plants come from is an issue easily taken for granted.  That is, where plants come from before your local retailer (but after your preferred narrative of creationism or evolution).  How convenient that we can go buy Lilium regale at the big box stores today, the same species that E.H. Wilson so lusted after that it took him seven years, three voyages to China, a broken leg, and a lifelong limp just to introduce into cultivation in the early 20th Century.

E.H. Wilson and Co.
 The allure of the exotic and unfamiliar is part of the reason why many temperate Asian species dominate domestic sales.  Yet there are many North American species that are unknown to gardeners, untested by growers, or ‘unimproved’ (transmogrified into cultivars) by breeders.  For these and other reasons these plants evade our gardens, and many people are missing out on the opportunity to cultivate species that are both attractive AND part of the indigenous ecological community.

Because we cannot preserve native communities themselves, The Walk Across Kentucky strives to preserve native genetics through responsible seed collection and propagation.  Seeds are collected or donated from across the state of Kentucky, and grown into mature plants here at a single site.  With proper record keeping and mapping we are able to track where everything originally came from, and potentially serve as a repository for seed, cuttings, or pollen of known provenance.   Even though a common species like red maple (Acer rubrum) may grow throughout eastern North America, red maples from Kentucky are genetically distinct from those in Vermont.  For less common species, safeguarding Kentucky genetics could prove invaluable in the future for reforestation, threatened species conservation, or just propagating local species that perform better in this region.

Below are two examples of collecting projects that have been recently undertaken for the Walk Across Kentucky collections.

Magnolia pyramidata
First: the pyramid magnolia, Magnolia pyramidata.  This magnificent small tree is virtually unknown outside of the Gulf Coastal Plain, yet there are confirmed reports of it from the most westerly part of Kentucky, near the banks of the Mississippi River in Fulton County.  The most recent data based on a herbarium voucher (UK), confirms the species location in 1970.  

Considered by many as a variety of M. fraseri, we hoped to locate this plant to confirm it still existed, and perhaps collect propagules to grow ex situ.  Kentucky appears to be the northernmost extent of the pyramid magnolias range, so collections from this location may have increased hardiness, among other things.  
Known distribution of M. pyramidata.  This species has only been found in the states shown above, and in those counties marked in green.

 As it turns out, the location of this plant in 1970 was since logged and developed into an industrial complex.  We can only hope that there are more plants hiding up in the loess bluffs that might someday be discovered; otherwise this species has been extirpated from KY and the few hundred mile radius surrounding.

'Boehler Knob'
Second, and on a slightly more positive note is Boehler Knob in Mclean Co., Kentucky.  This interesting site is a small mountain in the middle of a perfectly flat floodplain between Green River and Cypress Creek.  It is a mountain surrounded by soybean fields, and in actuality, it is an island of biodiversity that is isolated by agriculture.  
Some rescues from Boehler Knob, l/r, t/b: yellow trout lily, wild hyacinth, spider lily, cuneate trillium
 In fact, the site is so thick with wildflowers in the spring that it is nearly impossible to walk around without stepping on a trilliums, wild hyacinths, bluebells, and countless other spring ephemerals.  Thanks in large part to Neville Crawford who has tirelessly been collecting plants from Boehler Knob for almost 8 years, The Walk Across Kentucky now has propagated hundreds of plants from his original seed collections.  This includes the entirety of the ‘Shawnee Hills Ephemeral Bed’ and  innumerable other trees and wildflowers that now grow happily in the Shawnee Hills section of the WAKY.  
sandstone cliffs atop Boehler Knob, large drift of erect goldenrod
Solidago erecta flowers

We understand that sections of the Boehler Knob have now been opened up to logging, and the future of the site from a development perspective remains unclear.  We hope that the plants at this site can be protected or properly managed, and are thankful to Neville for sharing so many of them with us.  
Neville bringing another load of plants to The Arboretum
Sourcing native plants for your own garden can be more difficult than one might think. There are many nurseries and seed distributors in Kentucky that do a fantastic job of responsibly propagating wild collected material and making it available to consumers.  For each of these stellar nurseries (Prairie Dropseed, Roundstone Native Seed, Highland Moor, to name a few), there are a dozen others that care little about plant provenance, or in some cases, responsible collection.

We encourage people to try cultivating natives that are locally sourced whenever possible.  Or at the very least, consider something other than more ice pansies and marigolds.