Character;"B. subhowii";"B. psilophylla";"B. cucurbitifolia";"B. parvibracteata" "Leaf blade shape";"asymmetric, widely ovate";"nearly symmetric, widely ovate to cordate";"nearly symmetric, orbicular, 3–4 lobed";"asymmetric, narrowly oblique-ovate" "Leaf blade base";"asymmetric, oblique-cordate";"nearly symmetric, obtuse";"nearly symmetric, cordate";"asymmetric, oblique-cordate" "Leaf margin";"irregularly serrulate";"minutely serrulate";"minutely serrulate";"usually almost entire or occasionally crenate" "Inflorescence bracts";"ovate-oblong, 50 × 30 mm, glabrous, apex acuminate";"elliptic to ovate-oblong, 7–9 × 4–5 mm, glabrous";"subglabrous, caduceus";"triangular, 6–8 × 3–5 mm, glabrous" "Tepal number of pistillate flowers";"usually 5, rarely 6";"usually 5, rarely 6";5;"usually 4, rarely 6" "Phenology (flowering; fruiting)";"April-May; May-July";"February-March; March-May";"July-August; August-October";"September-October; October-December" Habitat;"700–1500 m alt., limestone, Yunnan; Vietnam";"100–700 m alt., limestone, Yunnan";"430 m alt., limestone, Yunnan";"263 m alt., limestone, Guangxi"