COULTER AND ROSE—NORTH AMERICAN UMBELLIFERAE. 207 
Bractlets generally obovate. 
Oil tubes large, solitary in the intervals. 
Fruit small (4 to 10 mm. long)....-.-.--.----------- 13. L. utriculatum. 
Fruit larger (12 to 14 mm. long)......-------------------- 14. L. vaseyi. 
Oil tubes indistinct, several in the intervals .....-.----- 15. L. caruifolium. 
Bractlets not obovate. 
FLOWERS WHITE. 
Bractlets not scarious at margin, but more or less tomentose or villous. 
Fruit glabrous. 
Fruit with lateral wings much broader than body... 16. 1. ellipticum. 
Fruit with lateral wings as broad as body or narrower. 
17. L. macrocarpum, 
Fruit tomentose. - 
Oil tubes solitary in the intervals ...-...-...---- 18. L. dasycarpum. 
Oil tubes usually 3 in the intervals ....22.2...--- 19. L. tomentosum. 
Bractlets secarious margined, not tomentose. 
Oil tubes solitary in the intervals; fruit glabrous ...--- 20, LL. orientale. 
Oil tubes several in the intervals; fruit pubescent -... 21. 1. nevadense. 
FLOWERS YELLOW, - 
Involucels pubescent. 
Fruit glabrous ........-..-----------.------------ 22. L. daucifolium. 
Fruit pubescent .......2.----------------------- 23. L. foeniculaceum. 
Involucels glabrous. 
Somewhat scabrous; pedicels 4 to 7 mmo... ...----- 24. L. vaginatum., 
| Glabrous; pedicels 10 to 12 mim ........---------- 25. LL. marginatum. 
BRACTLETS OF INVOLUCEL SMALL OR WANTING, 
Fruit from narrowly to broadly oblong. 
Leaves narrow in outline, generally primate. 
Fruit puberulent .......-----.----------------------- 26. L. oreganum. 
Fruit glabrous. 
Oil tubes more than one in the intervals. ..........------ 27. L, hallii. 
Oil tubes solitary in the intervals. 
- Flowers deep yellow; leaf segments minute 2.2.2.2... 28. L. leibergi. 
Flowers pale yellow; leaf segments much longer than the last. 
; 29. LT. martindatlet 
Leaves broad in outline, with primary divisions at least lernate, 
Leaves rather simply 1 to 3-ternate. 
Wings broad. 
Oil tubes always solitary in the intervals. .....-.-- 30. L. laevigatum. 
Oil tubes mostly more than one in the intervals. 
Low dwarf glabrous plants. ........--------------- 31. L. eusickii. 
~ Taller and puberulent..........-------------- 32. L. platycarpum. 
Wings narrow. 
Ovaries glabrous....-.--.------------------------ 33. L. triternalum. 
Ovaries puberulent. 
Ribs filiform ......2..2.------------------------- 34. L. robustius. 
Ribs sharp ....-...------------------------------- 39. DL. alatum. 
Leaves usually much dissected and with short segments. 
Glabrous throughout. 
Flowers yellow. 
Oil tubes solitary in intervals. 
Fruit wings broad ............-.-.--------------- 36. LL. grayi. 
Fruit wings narrow ..............--------------- 37. L. torreyt. 
