18a. Divisions of the perianth (4 to 6) all essentially alike --19.

18b. Perianth differentiated into sepals and 2 or 3 colored petals --21.

19a. Flowers in umbels --20.

19b. Flowers in dense round heads; petals 5 2a, in =UMBELLIFERAE=, p. 80.

19c. Flowers in spikes, racemes, or panicles 38, in =LILIACEAE=, p. 13.

20a. Ovary inferior, appearing below the perianth as a swelling at the apex of the stalk; flowers bright yellow; leaves linear =AMARYLLIDACEAE=, p. 14.

20b. Ovary inferior; flowers blue or white, terminating a flattened winged leafless flower-stalk 3a, in =IRIDACEAE=, p. 15.

20c. Ovary superior, i. e., in the center of the flower and separate from the perianth 31, in =LILIACEAE=, p. 13.

21a. Flowers in dense heads, yellow, 1 cm. wide or smaller =XYRIDACEAE=, p. 9.

21b. Flowers in umbels, blue or white, 2 cm. wide or larger =COMMELINACEAE=, p. 9.

22a. Flowers blue; ovary superior (defined under _20c_); stamens distinct from the other parts of the flower --23.

22b. Ovary inferior (defined under _20a_); floral structure complex; stamens attached to other parts of the flower and not resembling ordinary stamens in form or structure =ORCHIDACEAE=, p. 15.

23a. Leaves triangular-heart-shape at base; marsh plants 1a, in =PONTEDERIACEAE=, p. 10.

23b. Leaves not heart-shape at base =COMMELINACEAE=, p. 9.

GROUP 4, DICOTYLEDONES

1a. Foliage leaves all or princ.i.p.ally basal; flower-stalk either completely leafless, or bearing a single pair of opposite leaves only. Bracts and scale-leaves are not considered foliage leaves --2.

1b. Stem-leaves present on the stem, either one or more in number, and not limited to a single opposite pair --3.

2a. Leaves compound --7.

2b. Leaves simple --18.

3a. Stem-leaves all or chiefly opposite or whorled (the bracts of the flower cl.u.s.ters may be alternate) --4.

3b. Stem-leaves all or chiefly alternate --5.

4a. Flowers small and inconspicuous, the perianth none or greenish or chaffy, and never petal-like in appearance --50.

4b. Flowers with a white or colored petal-like perianth --66.

5a. Flowers small and inconspicuous, without any white or colored petal-like perianth --118.

5b. Flowers large or small, but with a white or colored petal-like perianth --6.

6a. Flowers small, not exceeding 3 mm. in length or breadth --144.

6b. Flowers larger, more than 3 mm. in length or breadth --166.

--7--

7a. Leaves twice to three times compound or dissected --8.

7b. Leaves once-compound --11.

8a. Flowers in racemes 2b, in =FUMARIACEAE=, p. 41.

8b. Flowers in umbels --9.

9a. Flowers about 3 mm. wide, white or greenish-white --10.

9b. Flowers 10-20 mm. wide, conspicuous 45b, in =RANUNCULACEAE=, p. 39.

10a. Leaflets 5-15 cm. long 5b, in =ARALIACEAE=, p. 80.

10b. Leaflets not over 2 cm. long 16a, in =UMBELLIFERAE=, p. 81.

11a. Leaflets 2 3a, in =BERBERIDACEAE=, p. 40.

11b. Leaflets three or more --12.

12a. Leaflets entire or very finely toothed --13.

12b. Leaflets coa.r.s.ely toothed or lobed --15.

13a. Flowers irregular, in dense head-like umbels 37a, in =LEGUMINOSAE=, p. 61.

13b. Flowers consisting of a greenish or purplish bract wholly or partly enclosing a fleshy spike 2, in =ARACEAE=, p. 8.

13c. Flowers regular, solitary or in loose cl.u.s.ters --14.

14a. Leaflets reverse heart-shape, not over 2 cm. long =OXALIDACEAE=, p. 64.

14b. Leaflets 4-10 cm. long 1c, in =GENTIANACEAE=, p. 88.

15a. Flowers with colored or white petals and green or colored sepals --16.

15b. Flowers with one kind of perianth only (calyx), with broad and petal-like parts 32, in =RANUNCULACEAE=, p. 38.

15c. Flowers with white petal-like sepals and small inconspicuous petals 38b, in =RANUNCULACEAE=, p. 39.

16a. Petals and sepals each 4 31, in =CRUCIFERAE=, p. 44.