[2] The genus has two species, one found in the Balearic Islands and north-west Africa, the other in east China, Korea, Japan and adjacent localities.

The flowers appear in the autumn and are borne in a dense raceme containing small narrow bracts.

Individual flowers are star-shaped, small, and with pink or more rarely white tepals.

The genus (represented by B. japonica) occupied a basal position in the Hyacinthinae in a 1999 molecular phylogenetic analysis, suggesting an early evolutionary origin.

[6] As of March 2013[update], the World Checklist of Selected Plant Families recognized two species:[7] Ali et al. (2012) suggest that B. numidica is not related to B. japonica and should be transferred to a genus of its own.