Tuesday, May 24, 2016

Solidago ptarmicoides (white goldenrod)

Solidago (goldenrod) is special genus for Kentucky.   Not only is it (generically) the state flower, but over 30 species grow in Kentucky; several of which are globally threatened or endangered, including Solidago albopilosa which grows nowhere else on earth.  For those who instantly cringe at the mention of ‘goldenrod’, it is worth dispelling the rumors that 1. They are a weedy group of plants (only a few attain such status), and 2. They cause allergies in the fall (completely false, goldenrod pollen is too heavy to be wind-dispersed).

The presumption that goldenrods are weedy has led many gardeners to shy away from their cultivation.  In fact, the majority of species make fantastic additions to both sunny and shady garden environments.  One such species is the ‘white goldenrod’, Solidago ptarmicoides.   It has only been reported in Kentucky a few times, and while it generally occurs in more northerly prairie communities, it is to be expected in dry open woodlands and barrens.  In Walk Across Kentucky Collections, it is thriving in a dry, sunny site amidst two bear oaks (Quercus ilicifolia) in the Cumberland Mountain Region.  

S. ptarmicoides (2014-202) in the Cumberland Mountain Region
As goldenrods go, Solidago ptarmicoides is quite uncharacteristic of the genus.  As the common name suggests, the inflorescences are predominately white as a result of the cream-colored ray flowers.  Leaves are small and linear, and the plants themselves grow much shorter than most goldenrods.  This species dissimilarity to most goldenrods has led many to accept it within a new genus, Oligoneuron.   In Oligoneuron, it becomes O. album because of its original name: Inula alba.  Because of a blatant paraphylly of Oligoneuron within Solidago, we have chosen to retain the name S. ptarmicoides.

Last season (2015) our mass planting of S. ptarmicoides remained in bloom from July until October, and was a huge hit for both staff and visitors.  The cream-white blossoms were prolific and dense, and our monocultured planting grew into a nice ground-cover.  This plant would be a great choice for areas with full sun, especially in dry rock-gardens.

Thursday, February 4, 2016

Podophyllum peltatum (mayapple)

There is an entire suite of native plants which are the first species to emerge as winter subsides, and which persist for only a short time.  These plants remain dormant for the majority of the growing season, emerging as harbingers of spring to maximize sunlight before the tree canopy has developed.  They are aptly named the ‘spring ephemerals’ and include some of the most stunning and well-known native wildflowers including trillium, Virginia bluebells, trout lily, and bloodroot.  Among their ranks is mayapple (Podophyllum peltatum), perhaps the most ubiquitous of all the ephemerals, yet whose flowers go largely unnoticed despite their considerable size.

Mayapple typically grows in colonies which spread belowground via rhizomes (underground stems that grow horizontally).  Borne along the rhizome are single stems which yield either 1 leaf, or bifurcate into 2 leaves.  The leaves are radially symmetric and after being pushed from the soil they open much like an umbrella. 
Mayapple leaves in various stages of emergence
Stems that bear two leaves produce a waxy white flower (1-2” across) from the axil where leaf bases are joined.  The flowers are thus hidden from above by the large leaves.  Likewise the mayapple fruits which resemble small lemons also tend to go unnoticed by humans, and are readily consumed by animals.  Turtles are regarded as primary dispersal vectors, though a variety of mammals may serve in this capacity as well. Mayapple fruit is considered by many people to be delicious, but be warned that all parts of the plant (including unripe fruit) are poisonous.
Waiting for a turtle?  A ripening fruit awaits dispersal

Podophyllum is a member of the barberry family (Berberidaceae), and until recently a genus that included a number of species of predominately Asian origin.  Currently, P. peltatum is the type species and sole member of Podophyllum after the Asian clades were reclassified into Sinopodophyllum, Dysosma, and Diphylleia.  Both the genus and specific epithet were named in reference to the distinctive mayapple leaf shape: “duck-foot-leaf” and “shield-shaped”, respectively.

Sinopodophyllum hexandrum (formerly Podophyllum hexandrum) is native to the Himalayan Region.  Leaves here are just emerging, and unlike Mayapple, flowers are pinkish and held above foliage.
Dysosma pleiantha (formerly Podophyllum pleianthum) is native throughout much of China.  Burgundy flowers hang below foliage as in Mayapple, but are borne in clusters (vs. solitary).

Diphylleia grayi (a close Podophyllum relative) is native to northern Japan.  Petals turn translucent when wet, leading to the common name 'skeleton flower'.

Should you consider cultivating mayapple, consider the natural ecology of this species.  Foremost, it is a colonizing plant that with spread over time.  This is not to serve as a warning against a potential garden bully (for it is not), but rather a suggestion of how stunning mayapple looks when grown en masse.  
Natural colony of maypple
Mayapple will reach 12-18” in height, and monocultures are equally as impressive as mixed plantings with other tall ephemerals such as Virginia bluebells or wild-hyacinth.  The ability of Podophyllum to tolerate a variety of sun and soil moisture conditions is remarkable.  Nevertheless, dappled shade in rich, moist soil is ideal. On the Walk Across Kentucky, mayapple colonies may be seen in the Appalachian Plateau, Arboretum Woods, Bluegrass, and Shawnee Hills Regions.
Podophyllum peltatum (2006-007) growing in the Bluegrass region of the Walk Across Kentucky.

Wednesday, October 28, 2015

Symphoricarpos orbiculatus (coralberry)

Symphoricarpos orbiculatus 2000-3453-A

Despite being ubiquitous across Kentucky (and all of eastern North America) Coralberry (Symphoricarpos orbiculatus Moench) is a species which, paradoxically, goes unnoticed by many people.  Perhaps it is due to being one of the smallest woody plants in our flora, with similarly diminutive leaves and tiny greenish-white flowers.  Other plants tend to comingle with coralberry, further obscuring its miniature components and creating something of a botanical chimaera in the forest.  It is a curious species for many reasons, but also a plant in the ‘indestructible’ category for landscaping purposes.
coralberry, entrance to Arboretum Woods, here co-mingling with Elymus spp., Sambucus, and others.

Coralberry is the type species for the ~20 taxa genus Symphoricarpos Duhamel.  The name comes from Greek, symphorein – bear together, and karpŏs – fruit; an allusion to the berries which are borne in clusters along each stem.  This species fruit are clearly its strongest advertisement, for in addition to them yielding the botanical name they also account for the various common names including coralberry, Indian currant, buckberry, and waxberry.  Furthermore, it is the fuchsia-purple fruit which appeal to us as landscapers as a result of being persistent through the winter months.   This is apparently due to the presence of saponin in the berries, a mildly toxic natural detergent.  Wildlife consider coralberry a culinary last resort throughout the winter, ultimately consuming fruit only if all other food sources deplete.

Though fruit remains primarily an ornamental attribute, coralberry should not be overlooked when it comes to supporting wildlife.  Coralberry is a member of the honeysuckle family (Caprifoliaceae) and its flowers are visited by bees, wasps, and flies, while foliage serves as a food source for caterpillars of several moth species.  Coralberry is low mounding shrub from 2-4’ whose spread is typically accomplished clonally when arching branches touch the soil and adventitiously root.  As a result, these small thickets serve as good cover and protection for a variety of small animals.
A large coralberry thicket surrounding a memorial bench in the Bluegrass region (Walk Across Kentucky)

A partially shaded woodland would be an ideal spot to see (and cultivate) coralberry.  However, it is a species adaptable to various extremes including deep shade to full sun, and wet to dry soils.  It can do just fine as a small woody backbone for shade gardens, meadows, and rainwater gardens where it will slowly spread itself.  Deer are known to browse coralberry, and in our experience it responds well (with vigor) with simulated browsing including hard-pruning, mowing, and burning.  
Shawnee Hills region (Walk Across Kentucky) growing in wet moderate-shade at the edge of pin oak grove

For those who have paid close attention to the progression of The Arboretum Woods, you might have noticed coralberry increasing in abundance.  We suspect this may be due in part to the elimination of Amur honeysuckle (Lonicera maackii), another member of the Caprifoliaceae whose niche is being replaced.  Certain native plants struggle to establish by seed through the carpet of the exotic-invasive wintercreeper (Eounymus fortunei), yet the ability of coralberry to clonally spread by stem-rooting have allowed it to bypass this impediment.  We are glad to see it on the rise.

Monday, October 12, 2015

Appalachian Magnolia Bed

There are many parallels between natural ecosystems and ‘garden’ ecosystems (those shaped by the hand of nature vs. the hand of man).   One such parallel is the unwavering reality of change in living systems – plants (among other life forms) grow, battle, and die.  For gardeners it may be easy to overlook the beauty of that concept in favor of frustration when prized plants get too big, become aggressive, or perish. 

For several years now we have been both the drivers and passengers of an evolving garden called ‘Magnolia Bed’ in the Appalachian region.  While the Magnolias planted within seem insignificant now, the long term goal is for this area to be a thick forest of bigleaf magnolia (M. macrophylla).    This post is intended to track to the garden as it changes over time, and thus far it has been an interesting study of species dynamics.

Above left: a severely overgrown patch of (predominately) black locust, devil's walking stick, sweetgum, and brambles.  Above right: The Native Plant Volunteer Team charging into the thorn forest.
After a month of clearing, the woody debris was fully removed and converted to turf for the following (2012) season.

All of the woody debris had been piled-up and covered with mulch on the far side of the bed.  Bigleaf magnolia seedlings were planted throughout the bed and protected from rabbits using plastic pots.  In an effort to smother the turfgrass, newspaper and cardboard were laid down before a heavy layer of mulch. 
The newspaper/mulch combo was very effective at killing turfgrass.  Winter weeds were hand-pulled prior to planting. 
Spring 2014 plantings included dwarf blazingstar (Liatris microcephala), Rockcastle aster (Eurybia saxicastelli), silky wild-rye (Elymus villosus), gray goldenrod (Solidago nemoralis), purple coneflower (Echinacea purpurea), streambank mock-orange (Philadelphus hirsutus), wild hydrangea (Hydrangea arborescens), and sweet pepperbush (Clethra acuminata).  The ironweed (Vernonia gigantea) and large mass of common milkweed (Asclepias syriaca) pictured above were holdovers from the previous tangle of woodies that reemerged after nearly 2 years buried.
To reduce weed competition during the first season following planted, spring oats (an annual cover crop) seed was broadcast into the mulch at the time of planting.  In late summer the oats had turned golden-brown (above).

A favorable spring and early summer led to a wonderfully thick garden in 2015.  Common milkweed (above background) continued to expand its range via underground runners. 
 Purple coneflower blossomed exceedingly well.
 Looking east into the Knobs region, a sea of common milkweed goes to seed.  Giant ironweed (background) also spread considerably (by seed) from the lone mother plant of 2014.

The bigleaf magnolias are finally starting to grow up.  Their steady growth in the next few years will begin to shade out  the sun-loving wildflowers, and we will start to shift to an understory of shade-tolerant ephemerals, ferns, and sedges.
October 2015, an abundance of seed remains from the coneflowers, milkweeds, wild-rye, and ironweed.  Some of the composites like New England aster (Symphyothrichum novae-angliae) provide the last flash of color this year.
Rockcastle aster
dwarf blazingstar

sweet pepperbush
common milkweed
giant ironweed