Sium latifolium (L) Greater Water Parsnip
NOMENCLATURE
Sium : from Greek, ________ : sion : water plant.
latifolium : broad leaved.
OTHER NAMES : Sium segetum. Broad leaved water parnsip, water Hemlock.
BOTANICAL DESCRIPTION
TYPE : stout erect, perennial, poisonous. Hel.
HEIGHT : 40-200 cm. STEM : Hollow grooved.
UMBELS : compound, terminal, flat topped 6-10cm diam. 20-30 smooth rays 1.5-4 cm .
Peduncle < to > than rays, leaf opposed, smooth. Terminal hermaphrodite. Lateral male.
LEAVES : submerged: 2-3 pinnate., linear lobes, present only in spring. Aerial: simply
pinnate, with 3-6(16) pairs of lobes. 12 x 4 cm, sessile, lanceolate to ovate, unequal at
base, serrate, with cartilaginous margin and teeth. Lower lvs long petiolate, the upper
with short sheathing petioles. Cotyledons contracted into a petiole.
BRACTS : 2-6, sometimes large, leaf like. Bracteoles 3-6, lanceolate.
FLOWERS : white. Petals papillose beneath, styles form a stylopodium. Fl. 7-8.
FRUIT: 3-4mm, ovoid, laterally compressed, constricted at commisure. Mericarps: thick
prominent ridges. 3 superficial vittae. Carpophore present Pedicels 5-10mm. Styles
v. short and stout, recurved in fruit. Stigma spathulate. 2n=20.
HABITAT : shallow water, fen ditches.
DISTRIBUTION : local, mainly S.E. of a line from Humber to Bristol Channel, decreasing.
C. Ire.: Shannon & Erne. Most of Europe, Siberia.
POISONOUS ROOTS : No harm to pigs and ox. Adds disagreeable taste to milk.
