KEY TO GENERA. CARROT FAMILY. 621 



Involucre of 2-4 linear bracts ; stylopodium depressed. 26. Apium. 

 Involucre none. 



Stylopodium large, conic ; tall introduced plant with filiform leaf-segments. 



27. Foeniculum. 

 Stylopodium depressed ; low native perennials with decompound leaves. 



28. Musineon. 

 it Petals white, greenish-white or rarely pinkish. 



Fruit nearly terete, not flattened either laterally or dorsally, or very slightly flattened. 

 Umbels compound ; leaves compound or simple. 



Ribs of the carpels all winged. 



Involucre none. 29. Cymoptents. 



Involucre of broad membranous bracts. 30. Phelloptenis. 



Ribs of the carpels distinct but not winged. 

 Ribs all corky-thickened. 



Annual ; leaves finely dissected. 31. Aethusa. 



Perennial ; leaf-segments broad. 32. Coelopleurum, 



Dorsal ribs slender, the lateral sometimes corky. 



Lateral ribs corky-thickened ; leaves simple or simply pinnate. 



33- Cynosciadium. 

 None of the ribs corky-thickened ; leaves compound. 



Annual ; leaves dissected into filiform segments ; fruit subglobose. 



34. Coriandrum. 



Perennial ; leaf-segments broad ; fruit oblong. 35. Ligusticum. 



Umbels simple ; leaves reduced to hollow jointed phyllodes. 36. Litaeopsis. 



Fruit laterally flattened. 



Umbels and leaves simple; no oil-tubes in the fruit. 



Ribs of the fruit not anastomosing. 37. Hydrocotyle. 



Ribs of the fruit anastomosing. 38. Centella. 



Umbels compound. 

 Fruit tubercled or bristly. 



Seed-face concave. 39. Spermolepis. 



Seed face flat. 40. Ammoselinum. 



Fruit smooth, neither tubercled nor bristly. 



Carpels strongly flattened laterally ; fruit nearly orbicular ; plants acaulescent. 



41. Erigenia. 



Carpels nearly terete, or only slightly flattened. 

 No oil-tubes in the fruit. 



Seed-face concave ; involucre present. 42. Conium. 



Seed-face flat ; involucre none. 43. Aegopodium. 



Fruit with oil-tubes. 



Seed-face concave ; oil-tubes numerous ; roots tuberous. 44. Eulophus. 

 Seed-face flat. 



Oil-tubes numerous ; ribs filiform or inconspicuous. 



Pericarp thin. 45. Pimpinella. 



Pericarp corky-thickened. 46. Berula. 



Oil-tubes 1-3 in the intervals ; fruit distinctly ribbed. 

 Umbels terminal or axillary. 



Stylopodium depressed ; leaves once pinnate ; oil-tubes 1-3 in 



the intervals. 47. Sium. 



Stylopodium conic ; oil-tubes solitary in the intervals. 



Ribs, at least the lateral ones, corky-thickened. 



Annuals ; leaves finely dissected. 48. Ptilimnium. 

 Perennials ; leaves decompound. 49. Cicuta. 

 Ribs not corky-thickened. 



Leaves decompound. 50. Carum. 



Leaves reduced to hollow jointed phyllodes. 



51. Harperella. 

 Umbels, at least the lower, opposite the leaves. 52. Celeri. 



i. ERYNGIUM [Tourn.] L. Sp. PI. 232. 1753. 



Mostly perennial herbs, with spiny-toothed lobed dentate or sometimes dissected, rarely 

 entire leaves, and dense bracted heads or spikes of small white or blue sessile flowers, sub- 

 tended by bractlets. Calyx-teeth rigid, pungent, or acute. Petals erect, the apex emarginate 

 with a long inflexed tip. Disk expanded. Styles slender. Fruit obovoid or ovoid, scaly or 

 tuberculate, ribless, somewhat flattened laterally. Carpels nearly terete, the oil-tubes usu- 

 ally 5. [Greek, a kind of thistle.] 



About 175 species, of wide geographic distribution in tropical and temperate regions. Besides 

 the following, about 25 others occur in the southern and western parts of North America. Type 

 species : Eryngium maritimum L. 

 Plants erect, tall ; stem-leaves spiny or bristly-margined. 



Leaves elongated-linear, parallel -veined. i. E. aquaticum. 



Leaves elongated-linear, reticulate-veined. j. E. virginianum. 



Stem-leaves palmately incised-pinnatifid. 3. E. Leavenworthii. 



Plants prostrate, slender ; leaves unarmed. 4. E. prostratum. 



