EAE=, p. 113.

6b. Flowers yellow; leaves minute =LENTIBULARIACEAE=, p. 105.

6c. Flowers white, in clusters; leaves linear-lanceolate, acute,
not hollow 1b, in =ALISMACEAE=, p. 3.

6d. Flowers greenish, solitary at the end of elongated peduncles;
leaves very long and ribbon-like, flat or trough-shape
1a, in =HYDROCHARITACEAE=, p. 3.

6e. Flowers minute, whitish or lead-color, in heads
=ERIOCAULACEAE=, p. 9.

7a. Leaves alternate --8.

7b. Leaves opposite --10.

7c. Leaves whorled --12.

8a. Leaves with thin sheathing stipules 1b, in =NAJADACEAE=, p. 2.

8b. Leaves without stipules --9.

9a. Flowers greenish, in a head =SPARGANIACEAE=, p. 2.

9b. Flowers pale yellow 1b, in =PONTEDERIACEAE=, p. 10.

10a. Leaves serrate 2b, in =NAJADACEAE=, p. 2.

10b. Leaves entire --11.

11a. Leaves 2 cm. long or less =CALLITRICHACEAE=, p. 68.

11b. Leaves thread-like, 2-8 cm. long 2a, in =NAJADACEAE=, p. 2.

11c. Leaves linear to elliptical, more than 2 cm. long
1b, in =NAJADACEAE=, p. 2.

12a. Leaves in whorls of 3, abruptly widened at the base
2b, in =NAJADACEAE=, p. 2.

12b. Leaves in whorls of 3, widest near the middle
1b, in =HYDROCHARITACEAE=, p. 3.

12c. Stems straight and erect, at leaves the flowers emerged;
leaves in whorls of 4 or more 2a, in =HALORAGIDACEAE=, p. 79.

13a. Leaves with numerous small bladders attached, each bladder 1-3 mm.
long =LENTIBULARIACEAE=, p. 105.

13b. Leaves without bladders --14.

14a. Leaves alternate --15.

14b. Leaves opposite or whorled --18.

15a. Delicate and rare plants growing attached to stones in running
water =PODOSTEMACEAE=, p. 48.

15b. Plants 2 dm. high or more, with roots in mud or sand --16.

16a. Leaves once-pinnate --17.

16b. Leaves 2-3 times pinnate 15b, in =UMBELLIFERAE=, p. 81.

16c. Leaves palmately dissected 1b, in =RANUNCULACEAE=, p. 35.

17a. Taste peppery or mustardy 34, in =CRUCIFERAE=, p. 45.

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