B. rotundifolium: annual; stems erect, stiff, glabrous, one foot or more high, branched above; leaves broadly ovate, the upper ones embracing the stem, and joined round the back of it, so that they appear perfoliate, the lowest ones tapering to a stalk; umbels terminal of 3-6 short rays, without any general involucre, the partial involucres very much longer than the flowers, consisting of 4-6 broadly ovate, yellowish bracts. - Hare's-ear, or Thorow-wax. - Cornfields in chalky soils. Fl. July.

B. aristatum, and B. tenuissimum, are very rare dwarf annual species with grassy leaves, the first with non-granulated, the second with granulated fruits.