Plant of the Month: Silver Bell

Silver Bell  Halesia  tetraptera, H. Carolina, H. monticola

What better plant to usher in the Christmas season?

H. tetraptera aren’t always associated with white Christmas’s however.  These small trees are actually native to mixed forests, often along streams, in the central and southeastern states, extending as far north as West Virginia, south to northern Florida and west to Oklahoma.  Silver bells can live up to 100 years.

Global Ranking:  G4G5  (see state rankings below)

Other Common Names:  Carolina Silverbell, Four winged Silverbell, Silverbell Opposum wood

SNR:  AK, MO, NJ, NY, PA, RI, SC, TN, TX
S1: IL,
S1S2:  KT,
S2: AL, OK
S3S4: VA
S3: WV
S4: NC, GA         Presumed extirpated in OH

Related species:

Mountain Si;verbell (H. monticola) up to 100 ft (30m) found primarily in the Appalachians differs from H. tetraptera only in size and is generally classed as the same species.

Two winged Silverbell or Snowdrop tree -- H. diptera,  a more southerly species.

Little Silverbell:  H. parviflora grows along the Gulf Coast, up to 20 ft (6m)

Bigleaf Snowbell, Styrax grandiflorius

American Snowbell Styrax americana  up to 10 ft (3m)

Range:

North to West Virginia, south to northern Florida and west to Oklahoma.  It grows mostly in the Piedmont mountains of the Carolinas, eastern Tennessee, Georgia and Alabama but is also found in pockets of the southeastern coastal plain, west Virginia, southern Indiana, southern Illinois, Kentucky, central Arkansas, southeastern Oklahoma, and historically in southern Ohio from where it now appears to have been extirpated.

Identification:

Silver bells produce abundant cream, or occassionally pink, 3/4 inch (2 cm) bell-shaped flowers that lend the tree its name.  The fruits or drupes have 4-wings, which in turn, offer an alternative common name:  Four-winged Silverbell.  Its oval leaves turn yellow in autumn.  Ht:  20-40 ft (6-12m), the mountain form is larger.  Flowering period:  March - May depending on location. 

Plant Communities:

In Piedmont areas, the species is associated with yellow-poplar (Liriodendron tulipifera), white ash (Fraxinus americana), red maple (Acer rubrum), white oak Quercus alba), American holly (Ilex opaca), eastern redbud (Cercis canadensis), and bigleaf magnolia (Magnolia macrophylla). In the southern part of its range it occurs with American beech (Fagus grandifolia), southern magnolia (M. grandiflora), American holly, various oaks, cabbage palmetto (Sabal palmetto), Florida maple (Acer barbatum), eastern hophornbeam (Ostrya virginiana), and eastern redbud (4). In the Black Mountains of North Carolina, Carolina silverbell is a significant associate in the northern hardwoods climax association at high elevations and in the cove climax and mesic slope associations at mid-elevations (10). It occurs and may share canopy dominance with eastern hemlock (Tsuga canadensis), yellow buckeye (Aesculus octandra), white basswood (Tilia heterophylla), sugar maple (Acer saccharum), and yellow birch (Betula alleghaniensis) in the Great Smoky Mountains and the Joyce Kilmer Memorial Forest (20,24,25,35). Prominent associates of the species in a gorge in the Blue Ridge Mountains of western North Carolina were northern red oak Quercus rubra), chestnut oak (Q. prinus), sweet birch (Betula lenta), yellow-poplar, flowering dogwood (Cornus florida), and Fraser magnolia (Magnolia fraseri).

Carolina silverbell is associated with the following forest cover types (Society of American Foresters) (13):
23 Eastern Hemlock
24 Eastern Hemlock-Yellow Birch
25 Sugar Maple-Beech-Yellow Birch
26 Sugar Maple-Basswood
27 Sugar Maple
28 Black Cherry-Maple
57 Yellow-Poplar
58 Yellow-Poplar-Eastern Hemlock
59 Yellow-Poplar-White Oak-Northern Red Oak
60 Beech-Sugar Maple
74 Cabbage Palmetto
76 Shortleaf Pine-Oak
82 Loblolly Pine-Hardwood
87 Sweetgum-Yellow-Poplar
91 Swamp Chestnut Oak-Cherrybark Oak

Wildlife:

The four-winged drups (seeds) that gives the tree it’s latin name,  are sometimes eaten by squirrels.  It produces a heavy flower crop in early spring, making it a great nectar plant prized by beekeepers for the resulting honey production.

Cultivation: 

Seeds require 2-3 months of warm moist followed by 2-3 months of cold moist stratification although even with proper treatment, germination rates are only about 50%.  The plant produces multiple stems and may grow as a shrub unless trained into tree form.  Sensitive to drought, mulch well.  Requires at least some shade in hot dry areas and can grow in fairly heavy shade.

Threats:

It is thinly distributed over its natural range, although a number of cultivars are propagated by the nursery trade.  Attractive to woodworkers, making it susceptible to exploitation.