Outstanding trees and shrubs appropriate for growing in the Delaware Valley are displayed in seven Featured Collections in the Kendal Crosslands Arboretum. These collections demonstrate how botany, horticulture, and landscape design can be successfully combined and in the process, educate residents and visitors to the Arboretum. The Featured Collections showcase four genera – Magnolia, Quercus (oak), Cercis (redbud), and Carya (hickory) on the Kendal Campus and four genera -- Magnolia, Cornus (dogwood), Hamamelis (witchhazel), and Ilex (holly) on the Crosslands Campus. Collections allow one to compare different species within a single genus, to assist the surrounding community in determining the appropriate plants for their landscape plans, and to provide an attractive landscape for Kendal Crosslands residents. Plants in the Featured Collections offer many attractive features, whether it is a flowering and fragrant tree in spring, soothing green foliage for shade in summer, colorful leaves and fruit in fall, or an architectural silhouette against the stark winter sky. Additionally, trees provide food and shelter for wildlife. Although many of the trees are newly planted, they represent gifts for future generations to study and enjoy.
Scroll down to select a collection. (Trees in other Featured Collections will be described later)
FEATURED COLLECTIONS: MAGNOLIAS
Worldwide, magnolias are cherished above all for their flowers. Growing as large shrubs or stately trees, they produce showy, fragrant blossoms that come in colors of white, pink, red, purple or yellow. While the flowers receive most of the attention, many magnolias also produce highly ornamental fruit – a prominent, cone-like structure decorated with shiny orange-red seeds. Some species are evergreen with glossy, leathery leaves and some evergreen types have buds, stems, and leaf undersides covered with attractive, coppery brown, felt-like hairs. Named after the French botanist Pierre Magnol, this ancient tree belongs to the genus Magnolia and is a member of the Magnolia Family (Magnoliaceae). There are more than 200 species of Magnolia native to the temperate, subtropical, and tropical regions of southeastern Asia, eastern North America, Central America, the Caribbean, and parts of South America. Depending upon the species and the hardiness zone one lives in, somewhere a magnolia will be in bloom every month of the year.
Magnolia flowers are borne solitarily and composed of 6 or more petal-like tepals. Unlike most other flowering plants where the petals and sepals are clearly differentiated, in magnolias these two floral parts are fused together and called tepals. The tepals are the showy parts of the flower, arranged in whorls of two or more. Beetles are the primary pollinators of magnolia flowers, in part because magnolias evolved long before bees and other flying pollinators were present on earth. The flowers do not produce nectar but produce large quantities of pollen which is high in protein and is an excellent food source for beetles. When pollinated the magnolia seed pods, resembling exotic-looking cones, split open to reveal shiny, orange-red seeds. The seed is surrounded by a brightly colored, fleshy aril that is high in fat and relished by songbirds. This fleshy covering provides migrating birds with a beneficial source of energy as they migrate south. Evergreen species of magnolia also provide shelter for birds and wildlife that stay north for the winter.
There are several excellent books about magnolias including The World of Magnolias by Dorothy J. Callaway (1994), Magnolias: A Gardener's Guide by Jim Gardiner (2000), and more recently The Plant Lovers Guide to Magnolias by Andrew Bunting (2016). Additional information on magnolias may be found on the Magnolia Society International website, www.magnoliasociety.org.
1. Evergreen Magnolias. The word “magnolia” immediately brings to mind our native Magnolia grandiflora, the iconic, stately Southern Magnolia with its large, deep green, glossy leaves and huge, fragrant, white blossoms – the state flower of Mississippi and Louisiana. Few trees rival it for year-round beauty. However it does have its drawbacks – both its shallow root system and the dry shade it creates make it difficult to garden beneath, and its large, leathery leaves drop continuously throughout the year creating a messy look. M. grandiflora grows well in sun to part shade and in well-drained soil; it is hardy from New York City southward to Florida and westward to California (Zones 6-10).
More cold hardy than the Southern Magnolia is another native, the Sweet Bay Magnolia (Magnolia virginiana var. virginiana, Zones 5-9). This is a smaller tree that is easier to fit into most gardens and is found growing along the eastern Coastal plain from Massachusetts to North Carolina. Though considered deciduous in its northern range it is evergreen in its southern range. There is also an evergreen form, Magnolia virginiana var. australis (Zones 6-10), native from South Carolina south to Florida and west to Texas. Flowers of both varieties are creamy white with a lemony fragrance and when the wind blows, the silvery undersides of the deep green leaves “twinkle” ornamentally. Sweetbay Magnolia performs well in full sun to full shade and thrives in normal garden soils as well as in marshy, wet ones.
Deciduous Magnolias with Saucer-like Flowers
2. Deciduous Magnolias with Saucer-like Flowers. This group includes the ever popular and most widely planted magnolia, the Saucer Magnolia (Magnolia ×soulangeana, Zones 4-9). Also called the tulip tree reflecting the shape and bright color of its flowers that come in various shades of white, pink, rose, purple, magenta, and burgundy, this French hybrid (Magnolia denudata x Magnolia liliiflora) was developed in the early 1800s. Saucer magnolias prefer fertile, acid, well-drained soil and they do not tolerate heavy wind or salt spray. Unfortunately early-flowering selections are prone to frost damage.
Related to these, but also less tolerant of winter cold and summer heat, is the spectacular magnolia from western China – Sargent’s Magnolia (Magnolia sargentiana, Zones 7-9). Though their early flowers may fall victim to late freezes, one spring season with untouched blooms will quickly make one forget the disappointments of years past. The size and the abundance of their huge, bubblegum pink flowers will weigh down the tree. The Goddess Magnolia (Magnolia sprengeri var. diva, Zones 5b-8), also native to China, flowers late enough to escape frosts and is considered the most beautiful of all magnolias displaying deep rose flowers on the outside and a streaked pale pink on the inside.
In its own category is the Oyama Magnolia (Magnolia sieboldii, Zones 5-9), a native to South Korea, southern China, and Japan where it grows as an understory plant and bears nodding, saucer-shaped, fragrant blooms after the leaves emerge. The pure white flowers have an attractive central cluster of deep maroon stamens. Commonly grown in Japanese tea gardens, this multi-stemmed shrub grows in full sun to full shade in any well-drained soil.
Deciduous Magnolias with Star-like Flowers
3. Deciduous Magnolias with Star-like Flowers. This group includes the Kobus Magnolia (Magnolia kobus, Zones 5-8), the Star Magnolia (Magnolia stellata, Zones 4-8) and a hybrid between these two, the Loebner Magnolia (Magnolia ×loebneri, Zones 4-8). All three are cold-hardy, heat-tolerant, and very adaptable plants, however late frosts may sometimes damage their early blooms. Very adaptable, they grow well in full sun and in a well-drained soil and are surprisingly wind resistant.
Magnolia kobus is native to Japan and South Korea where it grows as a tall, upright species. Flowers are usually white sometimes pink with tepal numbers ranging from 9 to 12.
Native to Japan and mostly shrub-like and multi-stemmed, Magnolia stellata is among the earliest of the magnolias to bloom with flower colors ranging from white to many shades of pink. The blossoms occur in great numbers and are extremely showy due to the large number of tepals per flower, ranging from 12 to 40.
Since Magnolia ×loebneri is a vigorous hybrid between the above two species, many cultivars have been developed from this cross, resulting in a diversity of habits (single-stemmed to multi-stemmed), flower colors (white to lilac purple), and tepal numbers, 8 to 30.
Large-leaved, Native Magnolias
4. Large-leaved, Native Magnolias. Less widely planted, but deserving of greater attention, is a group of large-leaved, native magnolias generally used as bold accents or shade trees. They can be found growing along the East Coast southward to the Florida panhandle, in the southern Appalachian Mountains, and westward to Arkansas and Louisiana. These magnolias grow best in moist, organically rich, well-drained soils in full sun to part shade and are generally intolerant of soil extremes (dry or wet). Protect from strong winds which may shred their large leaves. Hardy in Zones 5-9.
Cucumber Tree (Magnolia acuminata) and its smaller sibling, the Yellow Cucumber Tree (Magnolia acuminata var. subcordata) are the source of the yellow flower color of the many new hybrids with tulip-shaped, golden yellow blossoms. Brooklyn Botanic Garden was instrumental in the creation of the so called “yellow magnolias” incorporating the Cucumber Tree (Magnolia acuminata), the Yulan Magnolia (Magnolia denudata), and/or the Lily Magnolia (Magnolia liliiflora) into these hybrids.
The Bigleaf Clan – Bigleaf Magnolia (Magnolia macrophylla), Umbrella Magnolia (Magnolia tripetala), Fraser Magnolia (Magnolia fraseri), Pyramid Magnolia (Magnolia fraseri var. pyramidata) and Ashe Magnolia (Magnolia macrophylla var. ashei). These are medium-sized trees with huge leaves and large flowers that appear as/after the leaves unfurl. Magnolia macrophylla var. dealbata is the Mexican sister of big-leaved forms and is commonly called the Cloudforest Magnolia.
5. Hybrid Magnolias. Hundreds of hybrid magnolias have been developed over the past 200 years providing magnolia lovers with a wide range of floral characteristics (color, size, and fragrance) and plant habit (size, shape, and hardiness). The first hybrid dates back to 1820 when French botanist Etienne Soulange-Bodin hybridized M. denudata with M. liliiflora to create the world-famous Saucer Magnolia, M. ×soulangeana; it has become the most widely cultivated group of magnolias today. In Germany in 1914 the Loebner Hybrids were produced by crossing M. stellata with M. kobus, giving us the very hardy, multi-tepaled blooms of ‘Leonard Messel’ and ‘Merrill’. Another milestone occurred in mid-1950s when the U.S. National Arboretum crossed M. stellata with M. liliiflora and created “The Little Girl Series” – affectionately known as “The Girls” (Magnolia ‘Ann’, ‘Betty’, ‘Jane’, ‘Judy’, ‘Pinkie’, ‘Randy’, ‘Ricki’, and ‘Susan’), a magnolia perfect for the smaller garden. The quest for Yellow Hybrids occurred at the Brooklyn Botanic Garden, NYC starting in 1956 and spanning over some 40 years. M. denudata was crossed with M. acuminata, producing the first yellow magnolia, ‘Elizabeth’. Shortly thereafter the American species (M. acuminata) was crossed with an Asian species (M. liliiflora), producing ×brooklynensis which paved the way for such cultivars as ‘Hattie Carthan’, ‘Evamaria’, and ‘Woodsman’. Since the late 1980s an explosion of hybrids has occurred -- finding their way into gardens and landscapes around the world and leading the way for magnolias to become one of the most popular genera to grow and love.
The Magnolia collection is located on the Kendal and Crosslands Campuses. There are 49 trees representing 25 taxa on the Kendal Campus and 33 trees representing 13 taxa on the Crosslands campus. The total for both campus is 82 trees representing 32 taxa. There are 6 taxa duplicated on both campuses.
A detailed description of each of the 32 taxa listed below can be accessed by clicking on the botanical name. Maps showing actual locations on two separate maps can be accessed by clicking on the map name under the heading "Campus Location."
Kendal Campus Magnolias
Crosslands Campus Magnolias
Featured Collections: Cornus (Dogwoods)
THE DOGWOOD FAMILY
Nothing symbolizes spring more than the sight of a flowering dogwood. Native to eastern United States, Cornus florida is dearly loved for its large, white or pink inflorescences that blanket the tree just before the leaves emerge. After the blossoms fade, this small to medium-sized tree continues to enhance the landscape with its horizontal branching pattern, softening the edges of our homes. Bright red fruit and burgundy-colored leaves signal the arrival of fall, and in winter the bare branches become living, architectural statuary in the stark landscape.
Cornus florida is just one of a number of species in the genus Cornus. According to Paul Cappiello and Don Shadow in their book “The Genus Cornus, Dogwood”, the number of species ranges from 45 to 65 with 15 native to North America. In addition, new interspecific hybrids have been developed and introduced. The species range in size from the creeping, low-growing, herbaceous groundcover (C. canadensis), to colorfully multi-stemmed shrubs (C. alba, C. sericea, C. sanguinea), up to 30 foot-tall trees (C. florida, C. kousa). The small flowers may be arranged in flat-topped cymes (C. alternifolia, C. sericea) or surrounded by large, ornamental, petal-like bracts (C. florida). Cherished by wildlife, the rounded, colorful berries are displayed in hues of red, white, blue, or yellow. Finally for dramatic fall foliage the dogwoods are hard to beat, ornamenting the landscape in shades of burgundy, red, and orange.
Dogwoods are primarily deciduous and have simple, untoothed leaves with distinctive veins that curve parallel to the margins (edges). Most dogwood species have opposite leaves, while a few, such as C. alternifolia and C. controversa, have their leaves alternately arranged. In many species the flowers are borne separately in open clusters, while in other species, such as C. florida, the very small, yellow flowers are tightly clustered and surrounded by four, large, white or pink, petal-like bracts. The bark, especially those shrubs (C. alba, C. sanguinea, C. sericea) known by the color of their stems (yellow, red, orange, or coral), provide identification and winter landscape ornamentation. C. florida bark matures into grayish brown to blackish blocks while the mature bark of C. kousa exfoliates into a mosaic of tans, pinks, and grays. In winter against a snowy background, the bark of C. kousa is highly ornamental.
The fruits of all dogwood species are drupes that contain one or two seeds, are often quite colorful, and a few are quite tasty. C. kousa and C. mas are sold commercially as edible fruit trees. The fruits of C. kousa have a sweet, tropical pudding-like flavor in addition to hard pits while the fruits of C. mas are both tart and sweet when completely ripe and are very high in Vitamin C. For centuries they have been eaten in Eastern Europe both as food and medicine to fight colds. However the fruit of the shrubby species is mildly toxic to people, though readily eaten by birds. The native dogwoods are a favorite food source of the larvae of 118 different species of butterflies and moths.
Most dogwoods are reasonably tolerant of diseases if given minimal care and appropriate siting. Most will grow well in slightly acidic garden soil that is well-drained yet contains some moisture during hot and dry summers. Stem canker can be a problem in the ornamentally barked shrubs such as C. alba and C. sericea as well as C. alternifolia so it is best to keep those shrubs minimally stressed.
A breeding program at Rutgers University under the direction of plantsman Dr. Elwin Orton began in 1965 with the goal to develop novel cultivars of Cornus florida and C. kousa as well as interspecific crosses between the two. The birth of these improved dogwoods arrived in the early 1980s and the first six patented cultivars, botanically named Cornus x rutgersensis and known as the Stellar Series®, were Aurora®, Celestial®, Constellation®, Ruth Ellen®, Stellar Pink®, and Stardust®. They exhibited excellent hybrid vigor and disease resistance toward the growing threat of anthracnose. Two newer Rutgers’ introductions, Venus® and Starlight®, arose after Dr. Orton introduced the West Coast native, Cornus nuttallii, into his breeding program. These hybrids are listed botanically under Cornus x elwinortonii.
The destructive pathogen of the 1970s however has been the dreaded dogwood anthracnose caused by the fungus Discula destructiva that spread rapidly through populations of our native flowering dogwood, C. florida. The C. florida cultivar, ‘Appalachian Spring’, was selected in the early 1990s specifically for its resistance to dogwood anthracnose. Ironically it was found growing in the Catoctin Mountains of Maryland near the Camp David presidential retreat, an area where dogwoods had been decimated by the disease. The next serious threat to the flowering dogwoods occurred in the 1990s when powdery mildew (Microsphaera corni) arrived on the East Coast. Consequently powdery mildew resistant cultivars (‘Jean’s Appalachian Snow’, ‘Karen’s Appalachian Blush’, and ‘Kay’s Appalachian Mist’) were released in the early 2000s by the University of Tennessee’s Agricultural Experiment Station.
The genus name comes from the Latin word cornus meaning horn in reference to the strength and density of its wood. The common name, dogwood, is in probable reference to an old-time use of the tree’s hard, slender stems for making skewers once known as dags or dogs.
Classification of Cornus species
1. Big-Bracted Dogwoods (Cornus florida Group) – characterized by having large, petaloid bracts (a modified leaf that resembles a petal) that surround a compact cluster of flowers; red fruit occurs in clusters. This group includes our eastern North American species (C. florida), our western North America species (C. nuttallii), and a species from eastern Asia (C. kousa).
2. Non-Petaloid-Bracted Dogwoods (Cornus mas Group) – possess flowers surrounded by four, non-petaloid bracts (bracts that do not resemble petals) that are arranged in an umbel; oblong fruits appear in clusters and are red or purplish black. This group includes our western North American species (C. sericea), a species from Europe (C. mas), and several from eastern Asia (C. officinalis, C. chinensis).
3. Bractless Group (Cornus alba Group) – characterized by showy white flowers that do not possess modified or petaloid bracts; flowers are arranged in branched clusters; the clustered fruits are white, blue, or black. This group includes a species from eastern North America (C. amomum), from eastern Asia (C. controversa), and from eastern and central Asia (C. alba).
4. Dwarf Group (Cornus canadensis Group) – characterized by having minute clusters of true flowers surrounded by four, ornamental, petaloid bracts. C. canadensis is an herbaceous groundcover with edible, showy, bright red drupes.
An excellent book on the genus Cornus has been written by Paul Cappiello and Don Shadow, entitled “Dogwoods: The Genus Cornus” published by Timber Press in 2005. Another informative publication is “Dogwoods for American Gardens” by Willard T. Witte, Mark T. Windham, Alan S. Windham, Frank A. Hale, Donna C. Fare, Wayne K. Clatterbuck" https://extension.tennessee.edu/publications/Documents/PB1670.pdf University of Tennessee Agricultural Experiment Station, Knoxville, TN, 2002.
CORNUS FOUND ON THE CROSSLANDS CAMPUS
Photos and a detailed description of each of the 19 taxa listed below can be accessed by clicking on the botanical name. The actual locations on five separate maps can be accessed by clicking on map name under the heading "Campus Location."
|MapTree #||Botanical Name (# of trees)||Common Name||Campus Location
|5||Cornus alternifolia (3)||Pagoda dogwood||400's, CCNE|
|A||Cornus alternifolia 'Golden Shadows' Wstackman||Golden Shadows dogwood||CCSW|
|B||Cornus controversa [June Snow ™] 'June Snow JFS'||June snow JF' dogwood||CCNW, CCNW|
|2||Cornus florida (19)||Flowering dogwood||ALL|
|L||Cornus florida 'Appalachian Spring' (3)||Appalachian Spring dogwood||CCNW, CCSW|
|F||Cornus florida 'Autumn Gold'||Autumn Gold flowering dogwood||CCNW|
|D||Cornus florida [Cherokee Brave™] ‘Comco No.1'||Cherokee Brave flowering dogwood||CCNE, CCSW|
|E||Cornus florida 'Cherokee Princess' (2)||Cherokee Princess flowering dogwood||400'S|
|N||Cornus florida 'Jean's Appalachian Snow'||Jean's Appalachian Snow dogwood||400'S400'S|
|M||Cornus florida f rubra (3)||Red flowering dogwood||CCNW|
|1||Cornus kousa (13)||Kousa dogwood||ALL|
|G||Cornus kousa 'Pendula'||Weeping kousa dogwood||CCNW|
|3||Cornus mas (8)||Corneliancherry dogwood||CCNE, CCSE, CCSW|
|H||Cornus officinalis 'Kintoki'||Kintoki corneldDogwood||CCNW|
|I||Cornus sericea 'Flaviramea'||Yellow Twig dogwood||CCNW|
|O||Cornus sericea ‘Cardinal’||Red Twig dogwood||CCNW|
|C||Cornus x elwinortonli [Venus™] 'KN30-8'||Venus Hybrid dogwood||CCNW|
|K||Cornus x rutgersensis [Aurora®] ‘Rutban’||Aurora Hybrid dogwood||CCSW|
|J||Cornus x rutgersensis [Celestial ™] 'Rutdan'||Celestrial Hybrid dogwood||CCNE|