* Terrestrial plants with opposite leaves.
* Corolla without scales at the mouth of the tube.
(67) Pulmonaria - calyx tubular, the lobes not reaching to the middle; stamens included in the tube of the funnel-shaped corolla.
** Corolla having the mouth of the tube more or less closed by subulate scales.
(68) Symphytum - corolla tubular-campanulate, with five small teeth ; filaments entire.
(69) Scrophularia - corolla small, nearly globular, with five unequal lobes; stamens four, often with rudiment of a fifth.
(70) Lathraea - calyx bell-shaped, with four broad short teeth: upper lip of the corolla helmet-shaped.
* Two upper stamens longer than the two lower.
(71) Nepeta - calyx tubular, fifteen-ribbed; upper lip of the longtubed corolla straight, notched.
** Two upper stamens shorter than or only equaling to the lower. † Corolla distinctly two-lipped.
(72) Lamium - calyx regularly five-lobed; stamens longer than the corolla-tube.
†† Corolla apparently one-lipped.
(73) Ajuga - upper lip of corolla minute, tooth-like, entire or notched.
(74) Daphne - perianth four-cleft, often coloured; stamens eight.
(75) Ulmus - perianth bell-shaped, with four to six short lobes, and as many stamens.
(76) Asarum - perianth bell-shaped, regular, three-cleft; stamens twelve.
(77) Hippophae - perianth of male flowers with two small segments and four stamens, of the females tubular, minutely two-lobed.
(78) Buxus - perianth small, of four segments, in the male flowers with four stamens, in the females with three styles.
(79) Empetrum - perianth of six scales, in two rows, with external imbricating similar bracts, the males with three stamens, the females with six or more radiating stigmas on a very short style.
* Scales of the male catkins broad, imbricated; anthers longer than their filaments.
† Male and female catkins short, sessile, erect.
(So) Myrica - male catkins with spreading concave shining scales, the female ones shorter, with long protruding styles.
† †Male catkins cylindrical, usually pendulous.
(81) Alnus - flowers three distinct with four stamens under each scale of male catkins; female catkins small, ovoid.
(82) Betula - no distinct flowers; stamens six to twelve under each scale; female catkins short, cylindrical.
** Scales of the male catkins narrow-linear or divided; anthers small, on slender filaments.
(83) Salix - male and female catkins cylindrical, compact, the scales entire; stamens two, rarely three to five, with one or two gland-like inner scales.
(84) Populus - male and female catkins cylindrical, compact, the scales jagged; stamens several, within an oblique cup-shaped inner scale.