Dig deeper at SERNEC, a consortium of southeastern herbaria.

You may also want to check Trees, Shrubs, and Woody Vines of North Carolina

Read more about Silverbell at Vascular Plants of North Carolina.

Recent drafts of Weakley's Flora don't recognize the two varieties but do discuss them: "monticola," a large tree, restricted to the Southern Appalachians (and especially the Great Smoky Mountains), the corolla (18-) 20-30mm long, the style included, the anthers well inside the mouth of the corolla tube, and "tetraptera," a smaller tree more widely distributed, the corolla (12-) 15-20mm long, the style slightly exserted, the anthers just within the mouth of the corolla tube. Read more by downloading Weakley's Flora (2022).

SYNONYMOUS WITH PLANTS NATIONAL DATABASE:
Halesia tetraptera var. monticola   FAMILY Styracaceae

INCLUDED WITHIN VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 152-01-001?:

Halesia carolina   FAMILY Styracaceae

COMMON NAME:
Mountain Silverbell

WEAKLEY'S FLORA OF THE SOUTHEASTERN US (4/7/08):
Halesia tetraptera var. monticola   FAMILY Styracaceae

SYNONYMOUS WITH PLANTS NATIONAL DATABASE:
Halesia tetraptera var. monticola   FAMILY Styracaceae

INCLUDED WITHIN VASCULAR FLORA OF THE CAROLINAS (Radford, Ahles, & Bell, 1968) 152-01-001?:
Halesia carolina   FAMILY Styracaceae