Connecticut broadleaf is a tobacco grown in full sun in the Connecticut River Valley, the same region that grows Connecticut shade. It is a different plant grown a different way. Broadleaf plants are short and bushy with very wide leaves, and the crop is stalk-cut: the whole plant is cut at once instead of being picked leaf by leaf.
The leaf is thick and turns dark when cured. That makes it sturdy enough for the long, hot fermentation that produces a maduro wrapper, which is how most broadleaf is used. It is harder to roll than shade wrapper, and a good share of the crop is not fit to be wrapper.
Pennsylvania broadleaf, grown mainly in Lancaster County, is a related sun-grown leaf that is also used mostly for maduro wrappers. See wrapper types and colors.