532 UMBELLIFERAE. {Vor. Il. 
1. Conium maculatum LL. Poison 
Hemlock. (Fig. 2684.) 
Conium maculatum I,. Sp. Pl. 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 1/-3’ broad, the rays 
slender, 1/-1'4’ long; pedicels filiform, 2//-3/” 
long in fruit; flowers about 1’’ broad; fruit 114/’ 
long, about 1/’ 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. Bennet’s 
Herb, Cashes, Wode-whistle. June-July. 
32. SIUM L, Specs s he lhe 
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 inflexed 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, 2°-6° high; leaf-segments 7-17. 1. S. cicutacfolium. 
Plant weak, 1°-3° high; leaf-segments 3-7. 2. S. Carsont. 
1. Sium cicutaefolium: Gmel. Hemlock Water-Parsnip. (Fig. 2685.) 
Sium cicutaefolium Gmel. Syst. 2:482. 1791. 
S. lineare Michx. Fl. Bor, Am. I: 167. 1803. 
Stum latifolium of American authors, not 
of Linn. 
Erect, stout, branched, 2°-6° high. 
Lower leaves long-petioled, the upper- 
most nearly sessile; petioles sheathing at 
the base; leaf-segments 7-17, linear, or 
lanceolate, 11%4/-5’ long, 1%4//-12’’ wide, 
acuminate at the apex, sharply serrate, or 
the lowermost pectinately dissected; um- 
bels 2/-3/ broad, 8-20-rayed; rays 34/-1 4’ 
long; fruit ovate, compressed, about 114’’ 
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.) 
Stum Carsonit Durand; A. Gray, Man. Ed. 5, 
196. 1867. 
Stem slender, weak, 1°-2° long. Leaf-seg- 
ments 3-7, those of the upper leaves linear, 
or lanceolate, acute, or acuminate, 1/-2’ long, 
1'4’/-3/’ wide, sharply serrate; lower leaves 
A WA often floating and very thin, the segments 
i) broader and laciniate, or dissected; umbels 
r 
) 1/-2/ broad, 7-15-rayed; rays 6’/-12’’ long in 
fruit; fruit somewhat smaller than that of 
a the preceding species. 
. 
\ i 
i} i 
WA 
pe 
In streams, Massachusetts and Rhode Island 
to Pennsylvania. July-Aug. 
