Halesia n. : A genus of American shrubs containing several species, called snowdrop trees, or silver-bell trees. They have showy, white flowers, drooping on slender pedicels.

Example:
What tree should I plant in my front yard?

Taxonomy
Halesia, Halesia carolina, eastern North America, monticola, unranked, genus, free encyclopedia, Species, family Styracaceae, fruit, parviflora, five species, Ellis, H. carolina, taxa, specimens, taxonomy, dispute.

Defination from the web:
Halesia ( which is named after Stephen Hales ) , also known as (Silverbell or Snowdrop Tree) is a small genus of four or five species of ... Halesia parviflora Michx. - eastern North America. Halesia tetraptera Ellis - eastern North America ...