Monday, January 13, 2014

Native Green Medal Plants and Jenkins Arboretum

Oakleaf Hydrangea
In early January, Penn State Extension conducted a “Green Industry” conference at Delaware Valley College.  We’ve been collaborating with DelVal, The Pennsylvania Landscape /Nursery Association (PLNA) and The Professional Grounds Management Society (PGMS) for about 30 years to bring professionals in the green industry together for a day of learning and socializing. This year 175 people participated.

The afternoon keynote speaker was Dr. Harold Sweetman, Executive Director of the Jenkins Arboretum. Harold’s presentation was spellbinding. Great photography and beautiful plants are a winning combination. His message was about Green Medal Plants … plants native to the eastern United States that thrive in the Delaware Valley region and would be beautiful in residential and commercial landscapes throughout southeastern Pennsylvania. The designation is made by Sweetman and the Jenkins staff.  

Here, I’d like to share thoughts on a few of the Green Medal trees and shrubs. There are also Green medal herbaceous plants...wildflower and ferns.  But I’ll stick to the woody plants because I know them best.
You can see the entire list here And, I certainly won’t attempt to compete with the Harold's photographs by including lots of pictures! I encourage you to see multiple images of each species at the website link shown above.

One interesting thing about the Green Medal designation…. it is for the species not specific cultivars. For some plants (think Cornus florida) you’ll find many cultivars. But the focus of the program is to make us more aware of the species in general. You can branch out from there.

Ok, on to the plants. Maybe the reason I warmed up to Harold’s presentation so much is because I see the plants he discussed almost every day. I have most of them in my front or backyard. And we have some of them in the fledgling Almshouse Arboretum on the grounds of Neshaminy Manor Center where Penn State’s Extension office is located.

So here are a few woody plants that you really should consider adding to your landscape this year. What? You don’t have a landscape of your own? OK. Find a park, school, church, or other public area and set a goal to obtain each of the Green Medal plants.

Eastern Redbud. Cercis canadensis – not red buds…. purple/lavender buds! Before the leaves emerge! That last for weeks! This plant is simply stunning in early spring. White flowered forms are available. And, it also has beautiful clear-yellow fall foliage. There are many cultivars with interesting summer foliage... even variegated, if you must. Small tree.  Fits into existing landscapes.

Common Pawpaw. Asimina triloba – Ok, not so common. Of all the plants on the list, this one may be most unfamiliar to you. But after hearing Harold describe a Pawpaw Daiquiri, I know it has a future. My plants are still young and have not yet borne fruit.  But I have eaten it and they are as tropical tasting as a mango or bannana. Just wild. Pawpaw is tolerant of shade and mucho soil moisture which makes it a good fit for such otherwise challenging sites. Get at least two different individuals to insure cross pollination for fruit set.

Carolina Silverbell.  Halesia carolina or Halesia tetraptera - Looking for a small to medium sized, shade tolerant, flowering,  native tree. Gotta have Carolina Silverbell.  Silverbell refers to the white flowers that hang downward from the previous season’s growth. This plant requires good soil... .deep, moist, acidic, well drained but it will reward you with its unique attributes.

Sweetbay Magnolia. Magnolia virginiana – A semi-evergreen small tree. Ok, I just looked and the specimen at the Almshouse Arboretum is leafless. But the one year old stems are bright green! This magnolia is noteworthy for it flower fragrance. Shade and wet tolerant. Foliage is dark glossy green on top and silvery beneath.  Shade and soil moisture tolerance is a big plus.

Alternateleaf Dogwood. Cornus alternifolia – Here’s a plant I really want. And I hope I live a while because the older specimens have such great character. The appeal of this dogwood is not the flowers, foliage or fruit but the horizontal branching habit. Yes, it has flowers of consequence but since they appear after the leaves they do not have the impact of flowers on Cornus florida. Speaking of which, the very common Flowering Dogwood is still a great plant. In fact, it is hard to beat for flowers, form and fruit. With close to 100 cultivars and subspecies in the trade, you will have no problem locating something you like. Put it at the corner of your house, plant three or five in a cluster near a woods edge or set one as a specimen in front of a wall. You almost can’t go wrong with what plant authority Michael Dirr calls “the aristocrat of native flowering trees”.

Winterberry Holly
Winterberry Holly. Ilex verticillata ­– Want to make a big splash of color in you landscape? In mid-winter? Look no further than this native, deciduous holly. These plants are widely sold and dozens of cultivars exist. They have been bred and selected for heavy fruit set. I know a guy who has three acres of them that are cut for the florist trade. Red and yellow fruit are possible with red predominating. Yes, you’ll need one, dull male. That’s life. And there is not much sense in having a single female when half a dozen will really liven things up. These plants tolerate very wet sites. What better way to solve a landscape problem than by filling it with color. I have never seen a serious pest on this species.

Franklin Tree. Franklinia alatamaha – We don’t have space here to tell the fascinating history of this plant. And for landscape purposes I guess it doesn’t matter. This small tree (10-25 feet) produces beautiful, large, fragrant,  white flowers with bright yellow centers in mid-summer… for starters. Fall color is a beautiful reddish purple. The dark, fluted  smooth bark and interesting branch architecture  make it interesting when dormant.  Hard to transplant and maybe difficult to find except at specialty retailers.  
Most, (probably all) of these plants have important relationships with native insects and other critters. When you fill your landscape with such plants, you are not the only one who benefits.

One thing I have noticed over the decades of involvement with the Green Industry Conference at Delaware Valley College...we have no trouble finding outstanding horticulturists, like Harold Sweetman  right in our own back yard. Kind of like these native plants… you don’t have to go far to find a winner.

Finally, don’t miss seeing the plants we just discussed, and many more, live and “in person”.  Visit Jenkins Arboretum

1 comment:

Debby said...

Great to see your promotion of native plants. I've three of them in our small yard. I would omit Cornus alternafolia though as they are getting some sort of disease. Eric Burkhart of Shaver's Creek Enviro Center mentioned a few yrs. ago that the one in front of the Center has a fatal disease. I'm sorry I've forgotten the name. Ours is currently fine but I imagine will soon get same disease. Perhaps it's one of the pathogens mentioned in this NC article:
Thanks again for promoting natives. I particularly like Ilex verticillata because of the bright red berries in winter. Many people stop to comment on them so I have a chance to promote natives.