Monday, July 27, 2015

Notes on Aronia

Aronia x prunifolia (WAKY accession 2012-018)
The Rose Family (Rosaceae) is well known for genera indispensable to both gardeners and wildlife.   The fruits of this group typify their importance ornamentally and nutritionally.  Among just native rosaceous genera, most people are familiar with Amelanchier (serviceberries), Crataegus (hawthorns), Fragaria (strawberries),   Malus (crabapples), Prunus (cherries and plums), and Rubus (blackberries and raspberries).    Perhaps less-familiar is the genus Aronia (chokeberries), not to be confused with chokecherry (Prunus virginiana) – another rare Rosaceous species in Kentucky.

Aronia taxonomy is not for the faint of heart.   The type species [A. arbutifolia (L.) Pers.] was first placed in to Mespilus by Linnaeus.   Various authors have gone on to classify Aronia Medik. into Adenorachis, Crataegus, Halmia, Photinia, Pyrus, and Sorbus.  Some references continue to treat Aronia (and other genera) as Photinia, apparently due to floral and fruit traits deemed indistinguishable.   Nevertheless, recent phylogenetic evidence clearly refutes the sensu lato Photinia hypothesis.  A clear method by which Aronia (s. str.) may be riven from the aforementioned genera is by examining the adaxial midvein - only among Aronia will the presence of small red glands be visible.
note the dark-colored glands on the midrib

In Kentucky, as in the rest of Eastern North America, there are generally three Aronia species recognized:  Aronia arbutifolia (red chokeberry), Aronia melanocarpa (black chokeberry), and Aronia x prunifolia (purple chokeberry).   Red chokeberry is readily distinguished from black chokeberry based on red fruit (vs. black) and strongly pubescent leaves/pedicels/twigs (vs. glabrous).  Purple chokeberry is typically regarded as an interspecific hybrid between red and black chokeberry.  Evidence to support this theory comes from geographic distribution of species, leaf chemistry, cytogenetics, and reproductive biology, but a hybrid origin is also reinforced when morphology is considered.  Purple chokeberry exhibits several characters intermediate between each putative parent, including purplish/black fruits whose size is <black chokeberry and > red chokeberry.  Leaf pubescence of purple chokeberry is likewise intermediary between the strongly pubescent A. arbutifolia and glabrous A. melanocarpa.  
Aronia arbutifolia, red chokeberry

Aronia melanocarpa, black chokeberry

Aronia x prunifolia, purple chokeberry (a purported hybrid)
From a much more practical perspective, all of the aforementioned Aronia species make fantastic ornamental specimens, and it is curious why they are not more widely cultivated.  Chokeberries are all deciduous spring flowering shrubs with small simple leaves, nice fall color, and persistent fruit.  Rhizomatous  suckering is frequent in Aronia, but never in an aggressive manner.  The red chokeberry is common in wetter environments like bogs, seeps, and moist edges.  Black and purple chokeberry may occupy similar environments but can also be found in drier/thinner soils.  Partial shade to full sun is suitable for Aronia, though the latter yields more abundant flowers and fruit, and better fall color.  
Black chokeberry...who needs burning bush?

Aronia fruits are consumed by a number of bird species, and are edible to humans.  Black chokeberry in particular is widely cultivated in Europe and Asia where the fruits are used for jelly, juice, and wine, as well as eaten whole.   Several cultivars have been selected for fruit characteristics, and are available commercially.  It seems typical to observe chokeberries holding fruit for extended periods – to the point where the fruit dries into raisin-like pomes still attached to the plant.  It has been speculated that the astringent taste or low protein content may make the fruit less appealing to birds.  Nevertheless, the fruit is high in vitamins, minerals, and folic acid, which has led to increased human cultivation.  

Red and purple chokeberries can be found in the Appalachian Region on the Walk Across Kentucky.  After some taxonomic verification this month we determined that our black chokeberries had been misidentified – so this species has been put back on the WAKY wishlist.  As of this writing, the purple chokeberry fruit is nearly ripe while the red chokeberries are 1-2 months away.  As always, our specimens can be located by searching the Arboretum Explorer Website.

Wednesday, May 20, 2015

Elephantopus carolinianus (elephant's foot)

Within the Arboretum Woods is a native wildflower that typically goes unnoticed, despite being widespread throughout the forest.   It is a species in the aster/composite family (Asteraceae) commonly called Elephant’s Foot.   This species intricate yet small flowers are best appreciated up close, and mid-late summer is the perfect time to do so.

There are a few dozen species of Elephantopus worldwide, four in North America, and two in Kentucky.  The species common in the Arboretum Woods is E. carolinianus (Carolina Elephant’s Foot), while E. tomentosus with the far-cooler name 'Devil’s Grandmother', is native to Eastern Kentucky.   The former is readily identified by its leaves which are chiefly cauline during flowering rather than basal -as are the other species native to North America.

Elephantopus is the Latinized combination of Greek words Elephantos (Elephant) and pous (foot), given by Linnaeus to the type species, Elephantopus scaber, probably as an allusion to the basal leaf rosette.  The word elephantopus has since been borrowed as the specific epithet to both a species of giant tortoise (Geochelone elephantopus) and the extinct  heavy-footed moa (Pachyornis elephantopus).  Many of the (plant) species of Elephantopus have been investigated and recognized for their medicinal properties, due the presence of aptly named elephantopin, a compound that has anti-tumor activity.
Pachyornis elephantopus

Carolina Elephant’s Foot is easily propagated via seed, and performs nicely in cultivation as a handsome, though humble, forest wildflower.  Though it reaches 2-3’ tall, the uppermost portions of the plant are bare stems adorned with smaller leaves and terminal blossoms.  Medium shade and moist soils are the niche for this species, but we have seen it perform admirably in sunny/dry locations as well.  Light self-seeding is to be expected, but Elephant’s foots is otherwise a well behaved and easily cultivated botanical gem.

Thursday, March 26, 2015

Plant Conservation

Shawnee Hills Floodplain on the Walk Across Kentucky

There are three pillars on which The State Botanical Garden of Kentucky supports its mission: Education, Research, and Conservation.  Of those, the latter is perhaps the least tangible, despite by many accounts being the most important.  We can Educate through classes, events, and signage; and Research is succinctly conducted by staff, citizen scientists, and various university projects.  Conservation is more difficult to quantify.  The Walk Across Kentucky Collection Policy stipulates that all plant material be collected from wild provenance, in an ecologically sustainable manner.  We regularly make collecting trips in addition to working with other professional organizations and private land-owners from across the state to enhance the WAKY plant collections.  Incoming plant material runs the spectrum of the ubiquitous [like the sweetgums (2014-190) we collected from seed in Barren County last year] to the exceedingly rare, including the Kentucky Clover we received last year (a newly discovered species that is only found in Kentucky).

As highlighted by Janet Marinelli in her recent article, Botanical Gardens and Arboreta can serve an important role in plant conservation by collecting, curating, protecting, and propagating native plant species.  Included in her report are some fascinating data compiled by Botanic Garden Conservation International:

·         17,000 - number of native plants in the US

·         33% - percentage of US plants requiring conservation action

·         217 - number of US species now extinct or extinct in the wild

·         57% - percentage of federal endangered species that are plants

·         3.86% - percentage of federal endangered species expenditures received by plants

·         4,000 - number of nonnative species that have escaped into the wild, many of them weedy or invasive

·         $25 Billion - amount spent by the US every year to control invasive plant species
Monotropa uniflora (indian pipe) in an Eastern KY forest.  The exotic species Vinca minor (periwinkle) is covering the forest floor.
At the end of 2014, The Walk Across Kentucky Collections included 2652 individual accessions of trees, shrubs, vines, grasses and wildflowers.  Those individual plants and populations represent 520 Kentucky native species from 265 genera, within 99 families.  
The Mississipi Embayment Wetland Garden on the WAKY

The collections are continually expanding in size and scope.  If you would like to become involved in native plants or plant conservation at the State Botanical Garden, please contact us to discuss the many opportunities.  Additionally, the Native Plant Volunteer Group meets every Thursday from 10am to noon, and is open to the public.  For even more information on native plants, plant conservation, and ecosystem management, please save the date for the 2nd Annual Kentucky Botanical Symposium to be held on October 9th and 10th, 2015 (details will follow shortly).

Monday, March 2, 2015

2015 Launch of Arboretum Explorer™

We are very excited to announce that the Arboretum Explorer web page went ‘live’ in January of this year.  Arboretum Explorer is an online interface that allows users to search and locate The Arboretum’s plant collections, garden features, memorials, and more.  This website draws data from our recently renovated plant-records software and makes pertinent information available in a user-friendly format. 

Perhaps the most useful and comprehensive feature is the SEARCH tab that is displayed from the home page.  This feature allows users to search for a plant by scientific or common name, Genus, Family, or ‘area’ (such as Arboretum Woods).  If you search for ‘oak’, a list of the twenty-three native oak species will display on the bottom of the page.  To go one step further, click on ‘bur oak’ from the list and a new page will appear showing an image of a bur oak, a list of each individual bur oak (we have 53), and a map displaying the exact locations of each tree within The Arboretum (images below). 

The MAP tab is useful for visitors who can access Arboretum Explorer in a mobile-friendly format while walking outside.  This will allow visitors to see their current location on the map in addition to all of the trees, allowing for instant identification of unknown species. 

Finally, the FEATURES tab is a sortable and searchable means through which memorial trees and benches, birdhouses, specialty gardens, facilities, and more can be located.

Please note that Arboretum Explorer is a work in progress as well as a dynamic inventory that is changed and updated regularly.  We hope you will utilize this new tool for connecting with The Arboretum’s plant collections.

Arboretum Explorer can be accessed from: