ORDER LXI. UMBELLIFER.B. 829 



4. Flowers yellow or greenish 5 



Flowers white or blue 7 



5. Leaves pinnately divided Pastinaca, 19. Daucus, 22 



Leaves ternately divided 6 



6. Seed nearly terete Thaspium, 13 



Seed flat on one side, convex on the other Zisia, 12 



7. Seeds compressed , 8 



Seeds scarcely compressed 18 



8. Seeds compressed on the sides 9 



6eeds compressed on the back 16 



9. Leaves 3- parted Crypiotcenia, 1 1 



Leaves triternate or quinnate Cicuta, 8 



Leaves dissected, pinnate, or ternate 10 



10. Leaves bipinnate, segments ninnatifid Chcerophyllum, 23 



Leaves dissected, pinnate, or ternate 11 



11. Leaves much dissected 15 



Leaves pinnate or ternate 12 



12. Leaves ternate 18 



Leaves pinnate . . 14 



13. Involncre none Ifelosciadium, 5 



Involucre 2 — 4-leaved Neurophyllum, 10 



14. Involucre 1— 3-leaved Helosciadium, 5 



Involucre 5 — 6-leaved Slum, 9 



15. Involucre with parted leaflets Discopleura, 6 



Involucre none Leptocaulift, 7 



16. Leaves simple, terete Tiedmannia, 17 



Leaves compound 17 



17. Petioles inflated, 3-partcd ArcJiangelica, 16 



Petioles simple Archemora, 18 



18. Seeds linear OsmorrJdza, 24 



Seeds ovate-oblong Liguxticwn, 15 



Tribe I.— HYDRO COT YLE'^E. 



Fruit laterally compressed. Seeds flat on the face. Vittcs 

 2 or none. Umbels simple. 



Genus I.— HYDROCOT'YLE. Tourn. 5—2. 



(From the Greek hudor, water, and cotule, a cavity, from the locality of the plant* 

 in the water, and the cup-like appearance the leaves sometimes assume.) 



Margin of the calyx obsolete. Petals entire, ovate, acute. 

 Fruit flattened laterally, 5-ribbed. Herbaceous plants, aquatic, 

 creeping stems and peltate or cordate leaves. Flowers in sim- 

 ple umbels. Involucre 4-leaved. 



1. H. America'na, (L.) Stem glabrous. Leaves orbicular, reniforni, 

 slightly *7-lobed, crenate. Flowers few, sessile, in axillary umbels. — 

 White or greenish. If. May — June. Mountains. 2 — 3 inches. 



2. H. interrup'ta, (Muhl.) Stem terete, glabrous, creeping, branch- 

 ing. Leaves peltate, orbicular, doubly crenate. Flowers in small, 

 nearly sessile, capitate umbels, 4 — 8-flowered. Fruit broad. — White. 

 U . Through the summer. In wet soils. 3 — 4 inches. 



3. H. umbella'ta, (L.) Stem glabrous, creeping or floating. Leaves 

 peltate, crenate, emarginate at the base. Umbels many-flowered, on 

 long peduncles. Fruit somewhat tumid. Calyx slightly toothed.— 

 White. U. Through the summer. Grows in bogs. 4 — 6 inches. 



