532 



UMBELLIFERAE. 



[VOL. II. 



i. Conium maculatum L,. Poison 



Hemlock. (Fig. 2684.) 

 Conium maculatum L. Sp. PI. 243. 1753. 



Erect, much-branched, 2-5 high. Lower 

 and basal leaves petioled, the upper sessile or 

 nearly so, all pinnately dissected, the leaflets 

 ovate in outline, thin, the ultimate segments 

 dentate, or incised; petioles dilated and sheath- 

 ing at the base; umbels i'~3' broad, the rays 

 slender, I'-i^' long; pedicels filiform, 2"-3" 

 long in fruit; flowers about i" broad; fruit \W 

 long, about i" wide, its ribs very prominent 

 when dry. 



In waste places, Quebec and Ontario to Dela- 

 ware, Indiana and Michigan. Also in California and 

 Mexico. Naturalized from Europe. St. Bentu t ~ 

 Herb, Cashes, Wode-whistle. June-July. 



32. SIUM L. Sp. PI. 251. 1753. 



Perennial marsh herbs, with simply pinnate stem-leaves, the lower and basal ones often 

 pinnatisected, and compound large umbels of white flowers. Involucre and involucels of 

 numerous narrow bracts. Calyx-teeth minute. Petals inflexcd at the apex Stylopodium 

 conic or depressed. Styles short. Fruit ovate or oval, somewhat compressed. Carpels 

 with prominent ribs; oil-tubes. 1-3 in the intervals. Seed-face flat. [Greek name of a 

 marsh plant.] 



About 8 species, natives of the north temperate zone and South Africa. The following are the 

 only ones known to occur in the United States. 



Plant stout, a -6 high; leaf-segments 7-17. I. 5. eicuiaefolium. 



Plant weak, i-3 high; leaf-segments 3-7. a. S. Carsoni. 



i. Sium cicutaefdlium Gmel. Hemlock Water-Parsnip. (Fig. 2685.) 



Sium eicuiaefolium Gmel. Syst. 2:182. 1791. 

 5. lineare Michx. Fl. Bor. Am. i: 167. 1803. 

 Sium la li folium of American authors, not 



of I,inn. 



Erect, stout, branched, a-6 high. 

 Lower leaves long-pet ioled, the upper- 

 most nearly sessile; petioles sheathing at 

 the base; leaf-segments 7-17, linear, or 

 lanceolate, i#'-5' long, i#"-i2" wide, 

 acuminate at the apex, sharply serrate, or 

 the lowermost pectinately dissected; um- 

 bels 2'-3' broad, 8-ao-rayed; rays %'-i#' 

 long; fruit ovate, compressed, about !#" 

 long, the ribs prominent; oil-tubes 1-3 in 

 the intervals. 



In swamps, Nova Scotia to British Colum- 

 bia, south to Florida, Louisiana and Califor- 

 nia. Very variable in leaf -form. July-Oct 



2. Sium Carsoni Durand. Carson's 

 Water- Parsnip. (Fig. 2686.) 



Sium Carsoni Durand; A. Gray, Man. Ed. 5, 



196. 1867. 



Stem slender, weak, i-2 long. Leaf seg- 

 ments 3-7, those of the upper leaves linear, 

 or lanceolate, acute, or acuminate, i'-2' long, 

 i #"-3" wide, sharply serrate; lower leaves 

 often floating and very thin, the segments 

 broader and laciniate, or dissected; umbels 

 i / -2 / broad, 7-i5-rayed; rays 6 // -l2 // long in 

 fruit; fruit somewhat smaller than that ol 

 the preceding species. 



In streams, Massachusetts and Rhode Island 

 to Pennsylvania. July-Aug. 



