Callery Pear: Cut Them Down

Several years ago, I noticed something disturbing was happening to our prairie reconstruction.  Small little trees were popping up throughout the original prairie planting.  I could not figure out where they were coming from, but they looked like pear tree saplings.  It wasn’t until I saw a large white blooming tree in the spring that it all came together. 

Callery Pear

Although the flower clusters are beginning to fade, Callery pear’s white blooms are most obvious in the spring.  We planted them for their explosion of spring blooms and nice fall color, but this ornamental tree has become highly invasive.  It threatens native wildlife habitat and has become a nuisance for private and public landowners.

This once favorite tree was planted extensively throughout the U.S.  The Callery pear – also referred to as Bradford pear – formed a nice pyramid to rounded shape.  The vertical limbs made it a nice median and street tree as well, ultimately reaching 30 to 40 feet tall and 20 -30 feet in spread.  This Chinese native was a harbinger of spring for decades with its prolific white blooms.  An added bonus was its reddish-purple fall color.

Despite all those positives, these trees have become problematic. This non-native, flowering tree was assumed to be sterile, but it is not.  It now cross-pollinates with other cultivars of Callery pear to produce hybrid offspring.  The fruit is ingested by wildlife and birds that spread the seeds across the countryside and into your yards.  It is aggressively displacing native vegetation, causing economic and environmental damage. 

Escaped Callery Pears*

The message to property owners is to remove the trees now while you can easily identify them in bloom.  We need to keep them from spreading to native areas.  It doesn’t hurt my feelings to see them go, because they are a weak-wooded, thorny mess. 

Native alternatives to Callery Pear:

  • Eastern Rudbud (Cercis canadensis)
  • Serviceberry (Amelanchier arborea or Amelanchier ‘Robin Hill’)
  • American Plum (Prunus americana)
  • Chokecherry (Prunus virginiana)
  • Blackhaw Viburnum (Viburnum prunifolium)
  • Rusty Blackhaw Viburnum (Viburnum rufidulum)
Blackhaw Viburnum in spring
Blackhaw Viburnum fruit and fall color

We have cut down the culprit, but still have a bunch more saplings to remove this summer. There is one more larger tree to cut down near the Visitor Center. We will continue to eradicate these unwanted invaders in our prairies.  It will take time but I believe we can get the upper hand.  I would encourage you to remove them in your landscape as well and replace them with native trees.  Callery pear has no place in the landscape anymore. 

*Image Source

Plant Profile: The Versatile Viburnums

In addition to our interest in native trees, shrubs, wildflowers and grasses, one of the goals of the Arboretum is to grow plants which, while not native, are adapted to the rigors of the central Kansas climate. We are especially interested in displaying plants that are not widely grown in the area, but that show excellent hardiness and landscape potential.

The viburnums are a perfect example.  While not as widely known as forsythia and lilac, these shrubs deserve much more use in our landscapes. Not only do they offer year-around show of ornamental attributes, such as abundant floral displays, fragrance, outstanding fruiting characteristics, and fall color, they are also hardy and can serve a number of important uses in the landscape.

The Arboretum collection currently features a number of different viburnums, each displaying unique characteristics and qualities.  Most of the viburnums can be seen along the east border of the Arboretum, just south of the parking lot. A planting on the north bank of the Amphitheater features several additional kinds along with some newer varieties in the Pinetum.

Fragrant snowball viburnum – Viburnum x carlcephalum https://en.wikipedia.org/wiki/Viburnum_%C3%97_carlcephalum

The three most fragrant viburnums in the Arboretum’s collection are the Koreanspice Viburnum (Viburnum carlesii), fragrant viburnum (V. x carlcephalum), and Judd viburnum (V. x juddii). These three are somewhat similar in appearance because the latter two are hybrids involving a cross between the Koreanspice and another viburnum. They are medium size shrubs (6-10 feet tall). However, our collection also includes a dwarf form of the Koreanspice. All produce clusters of fragrant white flowers in April into May followed by inconspicuous black fruits.

Another fragrant type in the Arboretum is Burkwood Viburnum (Viburnum x burkwoodii). This semi-evergreen grows 8-10 feet fall and produces a white snowball-like flower cluster in April. The fragrance in somewhat sharper, almost spicy.

Like the burkwood viburnum, Willowwood viburnum (Viburnum x rhytidophylloides ‘Willowwood’) is semi-evergreen, retaining its furrowed, leathery leaves throughout much of the winter. This 7-10 foot shrub blooms in April and often to a lesser extent again in October. The blue-black fruits are attractive and can be quite abundant. Another form that is really attractive is ‘Alleghany’ which has tough, leathery leaves, attractive white flowers and abundant bunches of reddish-purple fruit.

Alleghany Viburnum. Photo by Emily Weaver

The Wayfaringtree viburnum (Viburnum lantana) grows as a large shrub or small tree (12-15 feet). While not fragrant to any degree, it produces an outstanding floral display in May, followed by red-black fruit in late summer that persists into fall. Fall color is often red, although it is not consistent.

Another large shrub is the Wentworth cultivar of the American cranberrybush (Viburnum trilobum ‘Wentworth’). The Wentworth viburnum was selected for its large, edible fruits, which progress in color from yellow to red to bright red and persist throughout winter. Birds seek out the fruits from fall through winter.  I have often thought that this shrub was at is best on bright winter days with the fruit highlighted against a snowy background. It is also attractive in May with its show of white, flat-topped flower clusters. A dwarf form of the American cranberrybush is found on the north bank of the Amphitheater.

Tucked up under the northeast corner of the Visitor Center is a viburnum that is very attractive. The Doublefile viburnum (Viburnum plicatum forma tomentosa ‘Shasta’) is stunning in bloom as the flowers are held horizontally above the branches.  It has insignificant fruit, but the spring flower show makes up for it.

Doublefile viburnum

The last two species in the Arboretum collection are the Blackhaw (Viburnum prunifolium) and southern or rusty blackhaw (V. rufidulum). These two species are native to Kansas and distinct from each other. Blackhaw viburnum is a large shrub or small tree that has smaller leaves and brighter fall color with oranges, yellows and reds. The dense flower clusters develop into purplish-black fruit that the birds love.

Rusty blackhaw is not widely available in the nursery trade at this time, but extremely adaptable and hardy. The glossy dark green leaves turn a nice burgundy-purple in the fall. Large, white, flat-topped clusters of flowers appear in early spring and later produce bunches of fruit that change from red to purple through the fall.  Again, many types of birds cherish the nutritious fruit.  These two native viburnums are my personal favorite, because they are the most adapted to our Kansas landscapes and have so many wonderful qualities.

Viburnum prunifolium. Photo by Janelle Flory Schrock

Viburnum rufidulum fruit. Photo by Emily Weaver

Any way you look at them, the viburnums are a versatile and highly ornamental group of plants that deserve a greater use in the landscape. We will continue to integrate new species and varieties into our plantings as development of the Arboretum progresses.






Plant Profile: Dwarf false indigo (Amorpha nana)

When we think of shrubs that grow in the prairie, lead plant (Amorpha canescens) is the first one that comes to my mind.  Rightfully so, the soft gray foliage and lavender flower spikes are a must for any summer prairie garden.  However, its lesser known cousin, dwarf false indigo (Amorpha nana) is blooming now in the Arboretum.  It makes you stop and take notice.

Dwarf false indigo can be found growing in the mixed-grass and shortgrass prairies throughout the Great Plains. In Kansas, I have seen it growing wild in Clark county.  It is not as widely distributed as lead plant, but I have found it to be quite adaptable.  It thrives in dry, open locations with plenty of sunlight.  Here in the Arboretum, it blooms in May but I have seen it bloom as late as mid-June.

The deep magenta flowers of dwarf false indigo have a sweet aroma like honey.  Each terminal flower cluster is covered in reddish-orange pollen that pollinators love to gather.  The flowers stand out against the bright green leaves.  This prairie shrub should not be pruned in the spring.  It blooms best from previous year’s growth.  A variety of pollinators flock to the fragrant blossoms, but the Silver Spotted Skipper butterfly use the soft leaves as a food source.  After the blooms, the small green seedpods develop, but turn dark brown later in the fall.

The name nana, meaning dwarf in Latin, refers to the shrub’s diminutive size, which ultimately reaches two feet tall.  While short, the deep tap root and finely textured leaves make it extremely drought tolerant.  Plant it en masse or along a border edge so you can enjoy the sweet fragrance of the flowers.  It prefers a well-drained soil, including clay and rocks.

Companion plants for this versatile shrub would be little bluestem (Schizachyrium scoparium), evening primrose (Oenothera macrocarpa), bottlebrush blazing star (Liatris mucornata), aromatic aster (Aster oblongifolius), shortstem spiderwort (tradescantia tharpii), narrowleaf coneflower (Echinacea angustifolia) and butterfly weed (Asclepias tuberosa).  This shrub deserves a place in your sunny prairie garden.

Join Us on Friday, May 12.

Dyck Arboretum of the Plains is offering a free wildflower to the first 25 families or individuals who obtain a new or renewed membership on Friday, May 12, for National Public Gardens Day!

We will also have FREE ADMISSION to the gardens for the day, and coffee and refreshments in the Visitor Center from 9-11 a.m.

THANK YOU TO EVERYONE WHO SUPPORTS THE DYCK ARBORETUM OF THE PLAINS!