Explore the Leventritt Garden - Arnold Arboretum

Explore the collections housed in the Leventritt Shrub and Vine Garden below.

Shrubs | Vines | Dwarf Conifers

Shrubs of the Leventritt Garden

Link to a shrub tour on Arboretum Explorer.

Shrubs come in many shapes and sizes, but they can be broadly defined as multi-stemmed woody plants, usually under 20 feet (6.1 meters) tall. The shrub accessions in the Leventritt Shrub and Vine Garden have origins in North America, Europe, and Asia, and include wild-collected species as well as cultivated varieties. Within this group there’s a lot of diversity in size, growth habit, and ornamental features such as flowers, fruit, and fall foliage color.

Flowering in the Garden peaks in late spring to early summer, but there are also shrubs that bloom at other times. Early bloomers like Chinese witchhazel (Hamamelis mollis), Daphne tangutica, and dwarf fragrant viburnum (Viburnum farreri ‘Nanum’) bloom in late winter or very early spring. Late bloomers include seven-son flower (Heptacodium miconioides) in September and common witchhazel (Hamamelis virginiana) in October or November.
A number of shrubs in the Garden provide winter interest, but one of the most eye-catching is red-osier dogwood (Cornus sericea). This large shrub displays bright red bark on its stems throughout the winter. The color is brightest on young stems so this plant is pruned back regularly to encourage new growth.
Large shrub or small tree? Some plants in the Garden could be called either large shrubs or small trees. Seven-son flower (Heptacodium miconioides), native to China, is one such plant. It can have one or several main stems, typically has a low-branching habit, and grows 15 to 20 feet (4.6 to 6.1 meters) tall. Whether a tree or shrub, this handsome plant offers fragrant white flowers in September, followed by a display of rosy pink calyces, then boldly exfoliating bark through the winter.
Subshrubs are plants that share traits both with herbaceous perennials and woody shrubs. Much of subshrubs’ top growth dies back in winter, but short sections (usually less than 10 inches [25 centimeters]) of woody stem persist at the base. Examples of subshrubs in the Garden include heathers (Erica spp.), bluebeard (Caryopteris x clandonensis), and English lavender (Lavandula angustifolia).
Colorful fruit adds ornamental appeal to some of the Garden’s shrubs in fall and winter. Many viburnums (Viburnum spp.) and hollies (Ilex spp.) have showy fruit—notable examples include Viburnum nudum ‘Winterthur’, which also develops red to purple fall foliage color; Ilex collina, a rare native holly that the Arboretum conserves; and winterberry (Ilex verticillata), a deciduous holly represented in the Garden by several cultivars such as ‘Red Sprite’ and ‘Winter Red’. Ilex species are dioecious (male and female flowers are borne on separate plants) so both female and male plants are needed for fruit production.

‘Nikko’, a low-growing cultivar of slender deutzia (Deutzia gracilis), is covered with white flowers in May.

The low-growing forsythia cultivar ‘Courdijau’ (trade name Golden Peep; Forsythis intermedia) blooms in early spring.

Seven-son flower (Heptacodium miconioides) blooms quite late, usually in late September here.

The Arnold Arboretum works to conserve Ilex collina, a rare native holly.

In mid-autumn the fruits of Viburnum nudum ‘Winterthur’ change from green to pink to deep blue as they mature.

‘Dark Knight’ bluebeard (Caryopteris x clandonensis ‘Dark Knight’) is a subshrub—it dies back to within a few inches of the ground each winter but then produces new growth and late summer flowers.

Watch a time–lapse video of a hops plant (Humulus lupulus) taken over a period of several days, allowing us to accelerate the observations that Darwin made in real time on the movements of the shoot system in beer hops.

Vines of the Leventritt Garden

New! Link to a vine tour on Arboretum Explorer.

Over 100 accessions of vines are displayed in the southwest section of the Leventritt Shrub and Vine Garden. These vines include species from North America, Europe, and Asia. Many of the vines have notable ornamental features such as showy flowers, colorful fruit, or bright autumn foliage color. Most accessions in the collection are woody vines, but a few, such as hops (Humulus lupulus), are herbaceous perennial vines.

Vines require some sort of support in order to grow upright. The type of support structure needed is determined by the vine’s climbing method. Common adaptations for climbing include:

Twining: As the vine’s stem tips grow, they move in a circular pattern until they touch a support such as a branch or wire. The vine then twines around the support, allowing the plant to grow upward. Most of the vines in the collection—including wisterias (Wisteria spp.), honeysuckles (Lonicera spp.), and kiwis (Actinidia spp.)—are twiners and are provided with sturdy metal trellises.
Twining petioles: Clematis (Clematis spp.) use this unique adaptation for climbing. The petioles (leaf stalks) twine around supports, allowing the vine to continue upward growth.
Tendrils: Tendrils are threadlike modified leaves that wind tightly around supports such as slender stems, strings, or wire. Look for tendrils on the grape (Vitis spp.) accessions in the collection.
Adhesive tendrils and aerial rootlets: These adaptations allow vines to cling directly to vertical surfaces such as walls or tree trunks. Adhesive tendrils are branched structures with small, round disks at the branch tips that adhere tightly to flat surfaces. Parthenocissus species such as Virginia creeper (P. quinquefolius) and Boston ivy (P. tricuspidata) have these adhesive disks. Other clinging vines—including climbing hydrangea (Hydrangea anomala ssp. petiolaris) and trumpet creeper (Campsis radicans)—cling to surfaces with clusters of hairlike aerial rootlets.

Several excellent specimens of clinging vines grow on the tall stone retaining wall near the stairs to the Larz Anderson Bonsai Collection; notice the aerial rootlets and extensive woody branching structure on the climbing hydrangea (Hydrangea anomala ssp. petiolaris) and Japanese hydrangea vine cultivars (Schizophragma hydrangeoides ‘Moonlight’ and ‘Roseum’).
The vine collection includes wisteria species native to Asia and North America. All produce beautiful racemes of flowers in late spring—look for Chinese wisteria (Wisteria sinensis) and several cultivars of American wisteria (W. frutescens) [Nomenclature note: The American species formerly listed as W. macrostachya, represented in the collection by cultivars ‘Blue Moon’ and ‘Aunt Dee’, is now considered a synonym for W. frutescens by most authorities.]
Hops (Humulus lupulus) is a vigorous herbaceous perennial vine perhaps best known for the use of its aromatic fruits in beer brewing. The gold-leafed cultivar ‘Aurea’ is especially attractive and makes a fast-growing cover on fences and arbors.
The vine collection includes accessions of clematis (Clematis) with bloom times ranging from late spring to mid-autumn. Clematis ‘Blue Dancer’, with nodding blue flowers is a highlight in mid spring to early summer. In summer, cultivars of hybrid large-flowered clematis bear showy flowers, including the ornate ‘Starfish’ with its burst of petal-like staminodes in the center. In September, you’ll see masses of starry white flowers on the sweet autumn clematis (Clematis terniflora) that grows along the perimeter fence bordering Centre Street. [Nomenclature note: This species has undergone several name changes and is sometimes listed under the synonyms C. maximowicziana or C. paniculata.]
The large-fruited kiwi of commerce (Actinidia deliciosa) is not hardy here, but several other Actinidia species are represented in the collection. Hardy kiwi (A. arguta) is a vigorous vine that produces edible, grape-sized fruits (Actinidia species are dioecious so both male and female plants are required for fruit production). Kolomikta kiwi (A. kolomikta) is grown primarily for its variegated foliage—green splashed with white, and often with blushes of pink in cool weather. Silver vine (A. polygama) is similarly variegated, minus the pink, and bears edible yellow-orange fruits.

The terraced vine collection in the Leventritt Shrub and Vine Garden.

Some vines can cling directly to vertical surfaces with tendrils tipped with adhesive disks, like these on a Boston ivy (Parthenocissus tricuspidata) stem.

The attractive variegated foliage of kolomikta kiwi (Actinidia kolomikta).

Showy foliage and aromatic fruits of golden hops (Humulus lupulus ‘Aurea’).

Other clinging vines use dense clusters of aerial rootlets, like these on a climbing hydrangea (Hydrangea anomala ssp. petiolaris) stem.

This Japanese hydrangea vine cultivar (Schizophragma hydrangeoides ‘Roseum’) clings directly to a tall stone wall in the Garden.

Twining is the most common adaptation for upward growth in vines. The stems of this Chinese wisteria (Wisteria sinensis) have twined around the trellis supports.

Sweet autumn clematis (Clematis terniflora) blooms in early autumn.

Dwarf Conifers of the Leventritt Garden

New! Link to a dwarf conifer tour on Arboretum Explorer.

A small collection of dwarf conifers is located on the slope between the Leventritt Shrub & Vine Garden and the Bonsai & Penjing Collection. There are also several dwarf and weeping conifers within the Leventritt Shrub and Vine Garden.

Dwarf conifers are variants of conifers; they grow more slowly and remain significantly smaller than normal for the given species. For example, white pine (Pinus strobus) normally grows 80 or more feet tall, but the dwarf white pine cultivar ‘Blue Shag’ reaches only about 3 to 4 feet tall, growing slowly to form a dense, globe-shaped plant. A general rule of thumb is that true dwarf conifers reach 1/20th or less of the normal height for a species, grow less than 6 inches per year, and are still less than 6 feet tall after ten years of growth. Intermediate dwarf conifers are a bit bigger—they may reach 1/10th of the normal height for a species, grow 6 to 12 inches per year, and may be 6 to 15 feet tall after ten years.

Dwarf conifers originate in a number of ways. They may be seedlings with genetic mutations that reduce their growth, or they may arise as branch sports (mutated growth on otherwise normal plants) that are then propagated. A fascinating and fairly common origin of dwarf conifers is from witches’-brooms [pdf] —dense, twiggy eruptions of growth on branches of otherwise normal trees. Witches’-brooms may be caused by mutations, insects, or diseases. New plants propagated from a witches’-broom retain a dwarf growth habit. Most conifers are difficult to propagate from stem cuttings, so grafting is the usual propagation method for dwarf conifer cultivars.

A number of dwarf conifers are noted for their colorful (non-green) foliage. Plants with yellow or gold foliage can make effective accents in the landscape, since the lighter, brighter color stands out from surrounding green tones. Look for the gold-tipped foliage of Chamaecyparis obtusa ‘Golden Nymph’, a dense, mounded shrub about 5 feet tall and wide. Blue-foliaged dwarf conifers are also eye-catching; an example is the broad, conical specimen of Picea pungens ‘Hunnewelliana’.
Some dwarf conifers sport unusual foliar characteristics. One striking example in the collection is the Korean fir cultivar Abies koreana ‘Silberlocke’, an intermediate dwarf conifer that has short, dark green needles that curve upward around the stem, revealing silvery white undersides. Adding to its garden appeal are the purplish upright cones, often frosted with sticky resin.
Cryptomeria japonica ‘Rein’s Dense Jade’ is a dense, upright growing cultivar of Japanese cryptomeria. Its closely pressed, awl-shaped needles give the branches a ropelike appearance. Foliage is bright green in summer and develops bronze tints during the winter.
Dwarf Alberta spruce (Picea glauca ‘Conica’) is a popular dwarf conifer. It has very short, fine needles that form a dense outer layer on its neatly cone-shaped form. The original plant was found in Alberta, Canada in 1904 by J. G. Jack and Alfred Rehder of the Arnold Arboretum.
Several slow-growing weeping conifers are included in the dwarf conifer and shrub collections. In the shrub garden, look for the weeping European larch (Larix decidua ‘Pendula’) gracefully trailing over a stone terrace wall. This deciduous conifer has lovely bright green summer foliage that turns gold in autumn. Even the bare winter branches add interest, especially when outlined with fresh snow. In the upper collection, a weeping Carolina hemlock cultivar (Tsuga caroliniana ‘LaBar Weeping’) is set off by a backdrop of red-fruited winterberry (Ilex verticillata ‘Winter Red’).