7b. Taste not peppery or mustardy 1a, in =HALORAGIDACEAE=, p. 79.

18a. Leaves pinnately compound 3b, in =HALORAGIDACEAE=, p. 79.

18b. Leaves palmately compound --19.

19a. Leaves opposite or in whorls of four 119a, in =COMPOSITAE=, p. 123.

19b. Leaves in whorls of 5-12 =CERATOPHYLLACEAE=, p. 34.

20a. Plants small, flattened, rounded or ovate, without distinction
of stem and leaf; the whole plant floating on or near the
surface =LEMNACEAE=, p. 9.

20b. Plant attached to the soil, with differentiated stem and
leaves --21.

21a. Leaves on long slender stalks, which bear also a cluster of slender
tubers near the leaf-base; leaves heart-shape
1b, in =GENTIANACEAE=, p. 88.

21b. Leaf-stalks without a cluster of tubers --22.

22a. Leaves all basal --23.

22b. Stem-leaves present --24.

23a. Leaves parallel-veined 1b, in =ALISMACEAE=, p. 3.

23b. Leaves net-veined 1b, in =NYMPHAEACEAE=, p. 35.

24a. Leaves opposite or whorled --25.

24b. Leaves alternate --26.

25a. Leaves less than 2 cm. long =CALLITRICHACEAE=, p. 68.

25b. Leaves more than 2 cm. long 1b, in =NAJADACEAE=, p. 2.

26a. Leaves attached by the center to the stalk
2b, in =NYMPHAEACEAE=, p. 35.

26b. Leaves attached by the margin --27.

27a. Leaves parallel-veined --28.

27b. Leaves net-veined, with a single mid-vein; lanceolate or elliptical
in outline 29b, in =POLYGONACEAE=, p. 28.

28a. Leaves not over 2 dm. long 1b, in =NAJADACEAE=, p. 2.

28b. Leaves very long and grass-like 14a, in =GRAMINEAE=, p. 5.

29a. Brown, yellow, or white plants, without green color --30.

29b. Plants with normal green color, at least in some parts --33.

30a. Stemless and leafless plants, consisting of flowers only and
partly underground 4a, in =ARACEAE=, p. 8.

30b. Stems climbing on other plants 1b, in =CONVOLVULACEAE=, p. 91.

30c. Stem and flower-stalks erect, not climbing --31.

31a. Corolla regular; stamens 6-12 1a, in =ERICACEAE=, p. 84.

31b. Corolla irregular --32.

32a. Sepals and petals each 3; flowers in simple racemes