The John W. Nason Garden is filled with dramatic textures and forms.  The fine texture of Nasella and Amsonia juxtapose beautifully with large-foliaged plants like Catalpa, Paulownia and Silphium.  Firmiana simplex, the Chinese parasol tree, is another dramatic character.  The two specimens located on the grounds of the Scott Arboretum are found behind Trotter Hall.  Firmiana hails from Asia and is a member of the Sterculiaceae or chocolate family.

Firmiana simplex flower close up. photo credit: J. Coceano

The Hillier Manual of Trees and Shrubs notes that Firmiana is “a noble foliage tree of medium size for the mildest climates.”  The large, rich green maple-like leaves are the main appeal; however, Firmiana is not simply a one hit wonder.  Creamy flowers are produced terminally in June and July on 10 – 20” panicles!  The fruits and subsequent seeds are most intriguing.   While fruits may vary in form, many are star shaped.  As the seeds mature, the pods inflate and then open allowing the single seed to dangle within the cluster.  Other attributes include yellow fall color, noticeable lenticels along the bark, and few if any pest problems.  Firmiana can be grown as a single stem specimen or as a multi-stemmed cutback shrub.  The Morris Arboretum uses the plant as a cutback shrub in the Rose Garden to great effect.  While a noted invasive in southern states (Texas), this 30-45’ tree bears further consideration in Mid-Atlantic gardens.  However, Charles Cresson noted some “seeding around” in his Swarthmore garden.

Firmiana simplex in flower. photo credit: J. Coceano

]]> http://blogs.scottarboretum.org/gardenseeds/2010/07/firmiana-simplex/feed/ 0 http://blogs.scottarboretum.org/gardenseeds/2010/06/actaea-rubra/ http://blogs.scottarboretum.org/gardenseeds/2010/06/actaea-rubra/#comments Tue, 22 Jun 2010 13:37:32 +0000 Sam Keitch http://blogs.scottarboretum.org/gardenseeds/?p=2130

The Terry Shane garden is looking incredibly flush with foliage this time of year, with countless woodland plants striving for attention.  One gorgeous species that is hard to miss is the red baneberry, Actaea rubra.  A small patch of plants is holding vivid red fruits just above a backdrop of green foliage.  Most people associate bright fruits with autumn, but the red and white baneberry produce fascinating berries during the summer.

The attractive fruit of Actaea rubra. photo credit: S. Keitch

Despite the fruit’s attractiveness, it is highly toxic, hence the ominous common name “baneberry.”  The other moniker, “doll’s eyes,” is self-explanatory,…

The Terry Shane garden is looking incredibly flush with foliage this time of year, with countless woodland plants striving for attention.  One gorgeous species that is hard to miss is the red baneberry, Actaea rubra.  A small patch of plants is holding vivid red fruits just above a backdrop of green foliage.  Most people associate bright fruits with autumn, but the red and white baneberry produce fascinating berries during the summer.

The attractive fruit of Actaea rubra. photo credit: S. Keitch

Despite the fruit’s attractiveness, it is highly toxic, hence the ominous common name “baneberry.”  The other moniker, “doll’s eyes,” is self-explanatory, as the berries have a black dot that resembles the iris of an eyeball.  This is especially noticeable as well as creepy on the white baneberry, Actaea pachypoda.

Trifoliate foliage of Actaea rubra. photo credit: S. Keitch

The entire plant is diminutive when compared to closely related bugbane species, with the delicate racemes being held only two feet above the ground, and reaching only about two inches in length.  The native bugbane species, Actaea podocarpa and Actaea racemosa, are much taller, and have much more dramatic inflorescences later in the summer.

All of the Actaea species, which now include all of the former Cimicifuga species, have gorgeous foliage.  The leaves are trifoliate and deeply cut, providing texture for a woodland setting.  The cultivars of the larger bugbane species also offer dark purple foliage, which is spectacular when topped with white flowers late in the season.   However, the fruits of the baneberry are the topic at hand, and are well worth a trip to the Scott Arboretum.  Please come and explore the Terry Shane garden and try to spot the red-hot berries of the red baneberry!

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It is dubious to make a claim that something is your favorite plant, but when someone asks me what my favorite native tree is, I can narrow it down to a few.  At the top of that short list is the American yellowwood, Cladrastis kentukea.  I have the tendency to point out a plant every five minutes and claim that it is my new favorite, so when I have a definitive answer, it is after great consideration. Without hesitation, I can say that the Yellowwood is my favorite native tree. Right now there are several large ones putting on a spectacular show at the Scott Arboretum.

Leaf of Cladrastis kentukea. photo credit: S. Keitch

The common name is self explanatory, as the vascular system produces yellow wood.  The range of the yellowwood is not a contiguous expanse as many trees of the Appalachia are, but consists of small endemic regions that are located sporadically from the southeastern United States into the Midwest.  The foliage is very handsome, with each compound leaf reaching about one foot long and consisting of leaflets that are roughly four inches each.  This is not only creates a stunning texture, but provides a nice backdrop for the graceful white inflorescences that resemble pendulous wisteria flowers.  The white flowers reach a foot in length and are typical of the pea family.  Currently they are falling all over the Terry Shane garden, creating the impression that there was a light dusting of snow overnight.  The foliage also turns a rich yellow in autumn, and the steel grey bark, much like a beech tree, carries the specie’s ornamental appeal well into the winter.

Flowering Cladrastis kentukea. photo credit:S. Keitch

Personally, I think the versatility of the yellowwood may be its strongest attribute.  It can tolerate sun or shade, acidic or alkaline soil, and even compact or saturated conditions.  However, it will grow more slowly when it has to overcome adverse conditions.  Its optimum culture would include rich, well drained soil, with rapid growth being encouraged by shade.  An interesting yet unfortunate trait of the yellowwood is its likehood of splitting apart at the crotch of the tree.  After forty years or so, unpruned trees will eventually reach a threshold of pressure at their lower crotch, where all of the major limbs come together. In a tree’s juvenile period, leads may be thinned out in order to alleviate pressure to extend its life expectancy.

A view of the trunk of Cladrastis kentukea. photo credit: S. Keitch

This is such a promising tree that I would recommend it to anyone looking for an addition to their property.  In fact, everyone should plant one.  Please come to the Scott Arboretum for inspiration!  Once you are here, you will see yellowwoods all over the arboretum, in all of their glory.  Large specimens can be found in near the Wister Center, the Nason Garden, and Parrish Hall.

There is nothing more exciting than taking a hike and stumbling into a patch of the eastern redbud, Cercis canadensis.  It is quite common as an understory tree, with an extensive range from east coast to the central United States.  Right now the vivid purple flowers are abundant at the Scott Arboretum.  Although the straight species is exceptional by itself, there are several cultivars blooming in the Scott Arboretum that I would like to comment on.

The reason I love this small tree is its adaptability to sun exposure.  Naturally occurring in the understory throughout Appalachia, it is a nice candidate for confined spaces that may not receive direct sunlight, most notably alleyways or tiny yards that must conserve space for walkways.  Personally, I think every homeowner that has an ideal woodland edge should interplant young eastern redbuds en masse.  It is a worthy investment for a spectacular spring show.  The redbud itself isn’t very large, only reaching twenty to thirty feet in height, with a slightly smaller width.

Cercis chinensis 'Don Egolf''. photo credit: S. Keitch

There are several cultivars of redbud, some of which I love, while others I have yet to come to terms with. One of the two cultivars that I would use as a focal points is: Cercis canadensis ‘Hearts of Gold’ which has typical redbud attributes, but the foliage is an outrageous chartreuse color. Another is Cercis chinensis ‘Don Egolf’, named after the shrub breeder from the U.S. National Arboretum, Dr. Donald Egolf. It may be the most potent redbud in the collection as the entire compact plant is smothered from the branch tips to the trunk in flowers. Everyone seems to exclaim with awe upon viewing either of these cultivars.

Foliage of Cercis canadensis 'Forest Pansy'. photo credit: S. Keitch

Other hot examples in the collection are the plantings of Cercis canadensis ‘Appalachian Red’ in the Glade Garden. C. ‘Appalachian Red’ is a vivid red to mauve tone. If you prefer more subtle characteristics, then the white flowering form, C. canadensis ‘Alba’ may be to your liking.  Personally, I think the purple leafed form, C. canadensis ‘Forest Pansy’ is one of the top choices.  The rich purple foliage emerges to extend aesthetic appeal and varies from green to cool purple depending on the leaves relative position to the outer portion of the canopy.

Another subtle redbud form is the tightly branched Cercis chinensis ‘Ace Of Hearts’.  The foliage is arranged along stout branches that zigzag from leaf to leaf, forming two columns of tightly arranged leaves.  The foliage and overall size of this cultivar is diminutive in comparison to the native species.

Cercis canadensis 'Alba'. photo credit: S. Keitch

Whether you are driving along the highway or strolling through the Scott Arboretum during the next week, be sure to notice the spectacular purple flowers punctuating the ever-changing spring landscape.

It is official.  Spring is on its way.  Everyone’s mood is improving along with the weather.  The doldrums of winter are fading as the remaining snow piles melt away.  Color is igniting the landscape once again as spring ephemerals pop up all around the Arboretum.  Pure white snowdrops, Galanthus nivalis, the winter aconite, Eranthis hyemalis, and myriads of tommies, Crocus tommasinianus are blanketing the ground.  The witch hazel display continues to be as spectacular as ever, but now there are other trees and shrubs beckoning your attention.  The Cornelian cherry was looking very impressive today, along with the beloved Persian ironwood, Parrotia persica.  With all of this dramatic change, surely we have cause to celebrate.

Over the last few days I have been performing the normal spring maintenance of cutting back perennials, removing debris, and spreading compost.  Wherever I turn a gorgeous hellebore flower is greeting me, telling me to take a moment to appreciate it in all of its splendor.  So I not only have to watch my footing and garden tools, but I have to resist gazing too long at one of my favorite plants.

Helleborus niger 'Praecox' photo credit: S. Keitch

The flowers of the Helleborus species are typical of the Ranunculaceae, consisting of five sepals, which strongly resemble petals.  Inside of the sepals are modified nectaries and stamens.  The flowers vary widely among species in their size and color, but breeders are constantly introducing exciting new selections.

The most common species grown for their large flowers are the Christmas rose, H. niger and the Lenten rose, Helleborus x hybridus.  These flowers are large, colorful and demand attention.  Commonly found at local nurseries, the Helleborus X hybridus are complex hybrids with H. orientalis and other species.  These are the most vigorous and dependable, and would be promising additions to your early-blooming entourage.

The foliage and stems of the different species are highly variable.  Species with aerial stems, also known as caulescent, bear flowers on year-old stems.  After flowering, the flower stalk dies back, forcing tender growth to be initiated each year.  This fragile growth is often susceptible to winter damage.  Most species are actually acaulescent, or stemless, and have extensive rhizomes underground which makes them more resilient than their stemmed relatives.

Helleborus x nigercors 'Honeyhill Joy' photo credit: R. Pineo

Hellebore leaves consist of three primary leaflets on a petiole that may be have further subdivisions.  Some are roughly toothed while others have their outer leaves moderately divided, and some are divided to very fine textures.

My favorite species for texture will always be the stinking hellebore, H. foetidus.  The lack of odor is somewhat disappointing, but the foliage more than compensates for the misnomer. The interspecific form Helleborus x sternii is another hybrid I would grow for its foliage alone.  The simple toothed leaves are a gray-green tone that appears to have a silver finish.

Helleborus Royal Heritage Strain photo credit: S. Keitch

There are many cultivars and rare species of hellebores throughout the Scott Arboretum.   I suggest a visit to the Harry Wood Garden, where the H. x hybridus ‘Kingston Cardinal’  and H. x nigercors ‘Honeyhill Joy’ are located.   Other large patches of H. niger ‘Nell Lewis Strain’ and H. foetidus ‘Wester Flisk’ are blooming in the Terry Shane Teaching garden and around the Lang Performing Arts Center.  I can’t imagine a better way to enjoy an outdoor walk as spring begins.

When all of the deciduous trees drop their leaves in the fall we get the opportunity to admire the bareness of a landscape.  There is something very pure about observing the structure of a tree, the sprawling nature of its branches, with the overall stature contrasting against the gray sky.   In the winter, however, after a beautiful snow, we also look downwards. Silhouettes of smaller trees and shrubs become apparent against a pristine white backdrop.  Today, I was walking past the fraternity houses, admiring the spectacular Hamamelis display, when I saw the outline of Zanthoxylum simulans.  The lateral spines weren’t exactly welcoming, but they were certainly captivating.  I commonly see our native species, Zanthoxylum americanum or flatspine prickly-ash at arboreta, but this specimen deserves more attention.

The formidable thorns of flatspine prickly-ash. photo credit: S. Keitch

If you’re like me and don’t like people poking around your garden, then the flatspine prickly-ash isn’t just a beautiful small tree, but a functional addition to your strategic home defense plan.  The thorns may reach an impressive size of three quarters of an inch, large enough to be a visual deterrent.  Other possible plants to bolster your living barrier include the hardy orange, Poncirus trifoliata, the wintergreen barberry, Berberis julianae, or the Devil’s walking stick, Aralia spinosa.

Multiple lead trunk of Zanthoxylum simulans. photo credit: S. Keitch

All kidding aside, the overall form of Zanthoxylum simulans is graceful, with its multiple lead trunks striving upwards of fifteen feet. I slightly favor the finer branches because the thorns appear even more pronounced.

As a member of the citrus family, or Rutaceae, flatspine prickly-ash possesses a common citrus family characteristic of aromatic foliage when crushed.  The compound foliage is a lustrous green tone that complements the inflorescences, which turn a beautiful pinkish-red in the late summer.  However, it is the fruit, namely the pericarp, which is sought in Asia for its medicinal and flavoring properties.  The common names including the word ‘pepper’ are derived from the culinary use of the dried fruits as seasoning herbs, described as more pungent than black pepper.

Close-up of the surly nature of Zanthoxylum simulans. photo credit: S. Keitch

If you want to try something a little bit different, I would recommend any of the Zanthoxylum species. They are an interesting specimen for tough conditions.  Of course, I must warn you of their surly nature and to be mindful of where they are located.  During my first encounter with Zanthoxylum simulans, I was left with a painful impression that I will never forget.

One of the most majestic of all the native trees in the landscape is the American planetree, Platanus occidentalis.  In its native habitat the American sycamore is found in low-lying areas especially growing along rivers and streams.  Its native geographic range is extensive. It can be found growing from Canada south to Florida and west to Minnesota and Texas.  While in its native habitat it thrives in moist soils, it will grow in a wide variety of soils in the home garden.

At the Scott Arboretum we used to have a fantastic specimen below Sharples Dining Hall.  This mature specimen had alabaster-white bark and towered over one hundred feet tall. After the death and subsequent removal of that large tree, we made sure to continue to represent this tree in our collections.

We added a young specimen in the lawn between Alice Paul and the train station.  This area has never drained very well and tends to be water-logged.  While most trees would not grow in these conditions it should be a perfect site for Platanus occidentalis.

American planetree is sometimes confused with the London planetree, Platanus x acerifolia which is the predominant shade tree along the Benjamin Franklin Parkway in Philadelphia. Platanus x acerifolia is a hybrid between P. occidentalis and P. orientalis.  It differs from the American planetree in that the bark color tends to be more yellow than white.

The American planetree is susceptible to anthracnose which can make the leaves shrivel or, when the weather is especially wet, can cause the tree to prematurely defoliate.  If this happens, the tree will often send out a new flush of leaves.  Most of the time the effects of this disease are more aesthetic than causing long term detriment to the tree.

The leaves on the sycamore are a fairly large and can add considerably to the quantity of leaves raked in the fall.  Also, the leaves have a fine fuzz or indumentum which can aggravate the eyes, skin and throats of some people.

In both its native habitat and in cultivation, the American sycamore is a favorite nesting spot for the Northern Oriole (syn. Baltimore Oriole). Locally, one of the very best specimens can be found in Sycamore Park in Lansdowne where there is a fantastic 300-year-old specimen.

I have really been feeling the transition of the seasons lately.  Leaves are dropping along with the temperature, everyone seems to be under the weather, and certain plants are popping out among the flat landscape.  Here at the Scott Arboretum, however, there is never a dull moment, and several plants are vying for attention.

Ilex ''Sparkleberry' in the BioStream. photo credit: R. Robert

The winterberries keep catching my eye, especially the mass plantings of Ilex verticillata ‘Winter Red’ and ‘Winter Gold’.  The ‘Winter Red’ cultivar has always been one of my favorite shrubs, with its powerful display of thick red clusters of berries that are very persistent.  My nose has also become captivated by the fragrant wintersweet, Chimonanthus praecox ‘Luteus’.  It is exhilarating to catch such a pungent scent while everything else appears lifeless.

Ampelaster carolinianus. photo credit: R. Maurer

Finally, another plant worth mentioning is the climbing aster, Ampelaster carolinianus , which is hidden within the Pollinator Garden.   Horticulturist Chuck Hinkle is responsible for planting this exciting late bloomer.  It was full of personality in the midst of a wind storm!  It blooms this time of year with quarter-sized lavender flowers with  yellow centers. These are just of a few of my favorite performers this month, but my top choice is  Acer pensylvanicum ‘Erythrocladum’ planted right outside of the Cunningham House.

The fascinating bark of Acer 'White Tigress'. photo credit: S. Keitch

Lately I have been taking the time to notice the subtlety of plants, and the more I inspect the different snakebark maples, the more I appreciate their intricacy.  Hiking along the pathway behind the Lang Performing Arts Building, it is hard to notice the old maples tucked among the understory.  Acer davidii , A. rufinerve, A. grosseri var. hersii, and A. capillipes can all be found in this small area.  Another gorgeous mature specimen is Acer ‘White Tigress’, which hovers over a large portion of the hydrangea collection.  This is believed to be a hybrid of Acer davidii and Acer tegmentosum.

The white stripes on Acer pensylvanicum 'Erthrocladum'. photo credit: S. Keitch

All of these species have such fascinating bark evolutions.  As their bark matures it becomes embellished with vertical white stripes.  There is considerable variation among the species, but my favorite color patterns are of juvenile Acer davidii.  The bark of the ‘Erythrocladum’ however, turns from a tan or orange tone to an impressive hot red during the winter.  The red and white pattern is almost reminiscent of holiday candy.  From a distance the young tips of the tree appear  pure coral red, which beckons pedestrians for a closer look.  Spectacular fall color, as well as delicate yellow flowers in the spring, provides this selection with ornamental appeal throughout the seasons.  This native striped maple only reaches a modest ten to twenty feet, making it an ideal specimen for tight locations.

Brillantly red branches of Acer pensylvanicum 'Erythrocladum'. photo credit: S. Keitch

Acer pensylvanicum is the only native snakebark species, and is a questionable addition to a garden, but the ‘Erythrocladum’ variety is positively exquisite.   Most of these small trees are considered short lived, but they are well worth the investment.  They are nice compact plants that should be planted along walkways in order to expose pedestrians to the fine details of their bark.  I encourage everyone to stop by the Arboretum office and take a moment to closely inspect this fiery wonder.

Last weekend I was fortunate enough to visit the Swarthmore garden of the renown plantsman Charles Cresson.  I had visited the property several years ago during the spring season with a professor and I remembered it being very impressive, so I immediately realized I was in for a treat.  Across his garden, camellias were unapologetically strutting their stuff.  Flowers of every variety, consisting of blood reds, pinks, whites, doubles, and anemone tones, were apparent in every pocket of the garden.

Aesthetically, the floral display was spectacular, but the background stories Charles explained in detail were equally as elaborate.  Charles delved into the history of each cultivar, complete with parentage, its origin, and the attributes that make it a worthy garden addition.

Camellia 'Winter's Interlude' photo credit: S. Keitch

The sources of Charles’ camellias are the J.C. Raulston Arboretum, the U.S. National Arboretum, the Morris Arboretum, Camellia Forest Nursery, and Dr. William Ackerman’s seedlings.  Many of Charles’s specimens are from original cuttings obtained decades ago, many of which are Ackerman’s original seedlings.

Top Row, Left to Right: C. 'NCSU #5', C. 'Ackerman 79-897', C. 'Snowflurrry'. Bottom Row, Left to Right: C. japonica, seedling of 'Snowflurry', C. 'Winter's Interlude'. photo credit: S. Keitch

To better understand breeders’ goals, several species and their ornamental attributes should be recognized.  Personally, I enjoyed the anecdote of Camellia oleifera, which survived the brutal winters of the ‘70s while other plantings perished.  It has since been extensively incorporated into breeding programs, including the Ackerman program, for its winter hardiness.  The specimen of Camellia oleifera ‘Lu Shan Snow’ was very impressive with its large white flowers, but its sexy cinnamon colored bark is what truly captivated me.  Camellia oleifera is also an important crop in its native range in China, where its seeds are used to produce a valuable tea-oil.

Camellia sasanqua is another heavily bred species, with more subtle characteristics.   It has noticeably smaller leaves and thinner flowers, but this is in no way a negative aspect.  It is a parent of countless cultivars, a favorite being a hybrid with Camellia oleifera, ‘Carolina Moonmist’.

Camellia japonica from wild collected Korean seed. photo credit: S. Keitch

Then there are the spring blooming varieties, derived from Camellia japonica.  During the eighties, expeditions focused on these colder locations to find more resilient offspring.  The spring blooming varieties consist mostly of Camellia japonica parentage.  These flowers are big and ostentatious, consisting of white, pink and red tones, and the glossy foliage is larger than other species.

There were many other rare species, and unusual hybrids collected by Charles, all outstanding with their unique traits.  Charles also introduced me to several species I was unaware of, Camellia cuspidata, C. chekiangoleosa, and the mid-blooming hybrids C. X vernalis and C. X hyemalis.

These hybrids exemplify the potential of camellias in the landscape.   As breeding continues, and hardiness boundaries are tested, camellias will soon gain a more dominant role in the landscape.  Soon, one will be able to select which floral structure, color, and bloom period is desirable and a cultivar with those traits will exist.  When it comes to floriferous evergreen shrubs, only rhododendrons are comparable.

Of course, this means that we will all inherit a dilemma, having to choose between rhododendrons and camellias.  In my mind, context always dictates a plant palette, but if one were comparing the two side by side, it would come down to personal preference.  The sleek and lustrous foliage of the camellia and its long bloom period are assets that should make camellias included by more designers.  I would encourage everyone to take a chance and try something new, something bold, especially as the plethora of new cultivars on the market continues to grow.

Camellia (Ackerman 80-276) photo credit: R. Robert

Several camellias are in bloom at the Scott Arboretum, many of which are descendants of the Ackerman program, including Camellia ‘Winter’s Interlude’ in the Harry Wood Garden.  We also recently added Camellia (Ackerman 80-276) to the Terry Shane Teaching Garden. This unnamed selection was donate by donated Charles Cresson and shows much promise.

When autumn comes to mind, one conjures up images of rich hues of red, orange, and yellow. There are countless species that have appreciable fall color, and the Scott Arboretum is full of examples. Right now there are several species on campus with spectacular fall color, some of my favorites being the American smoketree, Cotinus obovatus, the sourwood, Oxydendrum arboreum, the black gum, Nyssa sylvatica, and the Fothergilla gardenii. Then there is the staghorn sumac, Rhus typhina clump along Chester Road, which I find to be quite exquisite.

Rhus typhina along Chester Road. photo credit: S. Keitch

Personally, nothing signals the changing seasons like driving past a fiery clump of sumacs on the highway. Of course, these are not always deliberately planted, but are nonetheless, some of my favorite colors. I think of many things as the unruly scarlet foliage passes by, one of these being adversity. Many of us could learn some valuable lessons from this “pioneer” plant. It takes a bad situation, when everything is damaged and nothing else is growing, and transforms it into something ideal. The rugged old Sumac is a great indicator of things to come in the process of forest succession.

Bold foliage of Rhus typhina. photo credit: S. Keitch

On the other hand, you can also simply admire the plant for its bold features. The compound foliage creates an almost tropical effect, with several species and their cultivars offering a variety of patterns. White plumes appear in summer then turn to clusters of fuzzy red fruits that persist through the winter. Then there is the notorious growth habit. I like chaotic forms and things of a wild nature, and the sumacs all have such rambunctious character that it is hard not to admire their tenacity. You can plant them in one bed, and they’ll pop up in another!

Clusters of fuzzy red fruits of Rhus typhina. photo credit: S. Keitch

Staghorn sumacs can colonize an area by sending up aggressive suckers, which slowly radiate outward to create an open crown. This is not something a meticulous gardener would appreciate, but it is quite entertaining. Another rewarding practice is to heavily cut back a sumac to rejuvenate its appearance. I highly recommend showing a Sumac some tough love, because it will keep coming back for more.