1	"Perianth absent or of 1 whorl, or of 2 or more similar whorls (sometimes falling off as an operculum at anthesis); prostrate or floating aquatics or semi-aquatic herbs with distinctly opposite leaves; fruit more or less circular, dividing into 4 semicircular mericarps"	Callitriche
1	"Perianth of 2 distinct whorls (sepals and petals), differing from each other in shape, size or colour (calyx or corolla sometimes deciduous at anthesis); if ever aquatic, leaves radical or appearing so"	2
2	"Petals translucent, colourless or brownish; inflorescence of a spike, the fertile part rarely more than 30 cm long (usually much less)"	Plantago
2	"Petals white or coloured, not translucent; inflorescence various, but if ever a spike, the fertile part usually longer than 30 cm"	3
3	"Bracteoles present (between bract or leaf and calyx)"	4
3	"Bracteoles absent"	5
4	"Fertile stamens 4, staminodes absent or present; corolla 2-lipped, blue to purple"	Stemodia
4	"Fertile stamens 2, sometimes with staminodes; corolla cylindric, pale to rosy pink or white"	Gratiola
5	"Stamens 2; calyx and corolla 4- or 5-(rarely 6-)merous, the corolla c. equally lobed"	Veronica
5	"Stamens 5 or 4; calyx and corolla 5-merous, the corolla usually unequally lobed (but more or less equally lobed in Limosella and Digitalis)"	6
6	"Stem leaves opposite (at least in lower parts), linear to narrow-elliptic"	"Misopates {Misopates orontium}"
6	"Stem leaves alternate (if opposite in lower parts, leaves broad-ovate)"	7
7	"Corolla closed at mouth by palate on lower side, the base of the tube spurred on lower side"	8
7	"Corolla mouth open, with or without palate, the tube symmetrical at base"	10
8	"Leaves reniform to semicircular, with 5–9 rounded to triangular lobes, palmately veined; capsules dehiscing by irregular longitudinal apical slits"	"Cymbalaria {Cymbalaria muralis}"
8	"Leaves with lamina entire or with a pair of large basal lobes, pinnately veined; cap- sules dehiscing by an apical pore or irregular longitudinal slits"	9
9	"Plants procumbent to ascending; leaves petiolate; flowers solitary; capsules dehisc- ing by an apical pore covered by a detachable lid"	Kickxia
9	"Plants erect; leaves sessile; flowers in terminal racemes or spikes; capsules dehisc- ing by irregular longitudinal slits"	Linaria
10	"Erect herb; leaves c. ovate, usually crowded at base; inflorescence a terminal spike- like raceme"	"Digitalis {Digitalis purpurea}"
10	"Tender twiner or climber; leaves c. triangular, cordate or hastate at base, not crowded at base; flowers solitary in axils"	"Maurandya {Maurandya barclayana}"