16b. Petals and sepals each 5 or more --17.

17a. Leaves with stipules =ROSACEAE=, p. 51.

17b. Leaves without stipules 23b, in =RANUNCULACEAE=, p. 37.

--18--

18a. Stem-leaves a single opposite pair (basal leaves may also be present) --19.

18b. Stem-leaves none --23.

19a. Leaves entire --20.

19b. Leaves toothed or lobed --21.

20a. Flowers solitary; leaves broadly kidney-shape =ARISTOLOCHIACEAE=, p. 25.

20b. Flowers in racemes; leaves linear or lanceolate =PORTULACACEAE=, p. 34.

21a. Flowers in racemes; petals deeply toothed 23b, in =SAXIFRAGACEAE=, p. 51.

21b. Flowers solitary or few in a cl.u.s.ter; petals entire or nearly so --22.

22a. Petals 5 =GERANIACEAE=, p. 64.

22b. Petals 6 or more 2b, in =BERBERIDACEAE=, p. 40.

23a. Flowers or flower-cl.u.s.ters sessile, at or partly beneath the surface of the ground 4a, in =ARACEAE=, p. 8.

23b. Flowers or flower-heads solitary at the ends of the flower-stalks --24.

23b. Flowers or flower-heads numerous or several on each flower-stalk --38.

24a. Flowers yellow --25.

24b. Flowers not yellow --29.

25a. Juice milky 16, in =COMPOSITAE=, p. 115.

25b. Juice not milky --26.

26a. Aquatic or mud plants, with large entire leaves 1-4 dm. wide =NYMPHAEACEAE=, p. 35.

26b. Land plants, with smaller or lobed leaves --27.

27a. Flower-stalk scaly 110, in =COMPOSITAE=, p. 122.

27b. Flower-stalk bare or with 1 to 2 minute bracts --28.

28a. Flowers regular 10, in =RANUNCULACEAE=, p. 36.

28b. Flowers irregular, with a spur 3a, in =VIOLACEAE=, p. 75.

29a. Flowers obviously irregular, with a spur --30.

29b. Flowers regular or nearly so, without a spur --31.

30a. Leaves sessile or nearly so; stamens 2 =LENTIBULARIACEAE=, p. 105.

30b. Leaves petioled; stamens 5 =VIOLACEAE=, p. 75.

31a. Flowers 3 mm. wide or smaller; leaves thread-like 16a, in =SCROPHULARIACEAE=, p. 103.

31b. Flowers 6 mm. wide or larger --32.

32a. Ovary 1 --33.

32b. Ovaries numerous --37.

33a. Leaves lobed or cleft --34.

33b. Leaves entire or toothed --35.

34a. Leaves deeply 2-cleft; stamens 8 3a, in =BERBERIDACEAE=, p. 40.

34b. Leaf 1, palmately lobed; stamens numerous 1a, in =PAPAVERACEAE=, p. 41.

35a. Flowers dull red =ARISTOLOCHIACEAE=, p. 25.

35b. Flowers white or pinkish --36.

36a. Leaves entire; stamens with good anthers 5 13, in =SAXIFRAGACEAE=, p. 50.

36b. Leaves minutely toothed; stamens 8-10 14a, in =ERICACEAE=, p. 85.

37a. Leaves lobed or divided =RANUNCULACEAE=, p. 35.

37b. Leaves crenate or toothed 64a, in =ROSACEAE=, p. 56.

--38--

38a. Flowers of the composite type, with several or many small flowerets closely aggregated into a dense head surrounded by a calyx-like involucre of small bracts 10, in =COMPOSITAE=. p. 114.

38b. Flowers separate; variously cl.u.s.tered, but never crowded into involucred heads --39.

39a. Flowers in dense close spikes --40.

39b. Flowers in open loose cl.u.s.ters --42.