1. Sium Cicutaefòlium Schrank. Hemlock Water-Parsnip

Fig. 3171

Sium cicutaefolium Schrank, Bair. Fl. 1: 558.

1789. S. lineare Michx. Fl. Bor. Am. 1: 167. 1803. Sium latifolium of American authors, not of Linn.

Erect, stout, branched, 2°-6° high. Lower leaves long-petioled, the uppermost nearly sessile; petioles sheathing at the base; leaf-segments 7-17, linear, or lanceolate, 1 1/2'-5' long, 1 1/2-12" wide, acuminate at the apex, sharply serrate, or the lowermost pectinately dissected; umbels 2?-$' broad, 8-20-rayed; rays 1/2'-1 1/2' long; fruit ovate, compressed, about \\" long, the ribs promi-Inent.

In swamps, Nova Scotia to British Columbia, south to Florida, Louisiana and California. Very variable in leaf-form. July-Oct.

2. Sium Càrsoni Durand. Carson's Water-Parsnip

Fig. 3172

Sium Carsoni Durand; A. Gray, Man. Ed. 5, 196. 1867.

Stem slender, weak, 1°-2° long. Leaf-segments 3-7, those of the upper leaves linear, or lanceolate, acute, or acuminate, 1'-2' long, 1V-3" wide, sharply serrate; lower leaves often floating and very thin, the segments broader and laciniate, or dissected; umbels 1'-2' broad, 7-15-rayed; rays 6"-12" long in fruit; fruit somewhat smaller than that of the preceding species.

In streams, Maine, Massachusetts and Rhode Island to Pennsylvania. Perhaps an aquatic race of Sium cicutaefolium, but appearing distinct in Pennsylvania. July-Aug.