1. Cicuta maculata L. (common water hemlock, spotted cowbane)
Pl. 205 a, b;
glabrous, often glaucous, with at least some of the main roots
tuberous-thickened. Stems 50–200 cm long, erect or ascending, sometimes
purple-spotted or mottled toward the base, the base usually somewhat thickened,
hollow but cross-partitioned into chambers. Leaves alternate and sometimes also
basal (1 or few basal leaves sometimes present at flowering), the basal and
lower stem leaves mostly long-petiolate, the median and upper leaves
short-petiolate to nearly sessile, at least the lowermost sheathing bases not
or only slightly inflated. Leaf blades 2–40 cm long, broadly ovate to
triangular-ovate in outline, those of the basal and lowermost stem leaves 2 or
3 times pinnately compound, the ultimate leaflets 20–120 mm long, narrowly
lanceolate to oblong-lanceolate, narrowed or tapered at the base, finely to
coarsely toothed along the margins, occasionally with 1 or 2 basal lobes, the
margins usually also roughened with minute teeth, the main lateral veins mostly
ending in the sinuses between the teeth; those of the median and upper leaves
progressively reduced, 1 or 2 times pinnately compound, the uppermost
occasionally simple, the leaflets similar to those of the lower leaves.
Inflorescences terminal and axillary, compound umbels, mostly long-stalked.
Involucre absent or less commonly of 1–4 bracts, these shorter than the
rays, spreading to ascending at flowering, linear, with sharply pointed tips.
Rays usually numerous, 1.5–6.5 cm long, often unequal in length.
Involucel absent or more commonly of 3–7 bractlets, these mostly
shorter than the flower stalks, linear to broadly lanceolate, with thin, white,
papery margins, tapered to sharply pointed tips. Flowers mostly numerous in
each umbellet, the stalks 2–10 mm long. Sepals minute triangular teeth.
Petals obovate, narrowed abruptly to a slender, pointed extension at the tip,
white. Ovaries glabrous. Fruits 2.0–4.5 mm long, broadly
oblong-elliptic in outline, flattened laterally, glabrous, dark brown to
reddish brown with pale ribs, the mericarps with 5 ribs, these blunt and
somewhat corky. 2n=22. May–September.
throughout the state (U.S., Canada, Mexico). Sloughs, banks of streams, rivers,
and spring branches, margins of ponds and lakes, bottomland prairies, moist depressions
of upland prairies, and openings of bottomland forests; also roadsides,
railroads, and ditches.
maculata is perhaps the
most poisonous of all North American plants. Although all parts are toxic, the
tuberous roots, swollen lower stems, and new growth are considered the most
poisonous parts of the plants. The active compounds, a series of polyacetylenes
(including cicutoxin and cicutol), are quite different from the alkaloids found
in Conium and produce much more violent symptoms. Ingestion of a
walnut-sized portion of the root has been suggested as sufficient to kill an
animal the size of a cow.
In his revision
of Cicuta in North America, Mulligan (1980) recognized four varieties of
C. maculata, two of which were reported for Missouri. These are differentiated mainly
based on differences in details of fruit morphology, and flowering specimens
cannot be determined below the species level. Thus, the distributions listed
below for var. bolanderi and var. maculata are relatively inexact.
A third variety, var. angustifolia Hook., is unique in its subglobose
fruits, shorter styles (mostly less than 1 mm), and median and upper leaves
with narrower main leaflets (more than 5 times as long as wide). It is widely
distributed to the west of the state but has been collected in southeastern Kansas and eventually may be found in Missouri. The other variety, var. victorinii
(Fernald) B. Boivin, occurs mostly in the Pacific
Northwest and has ribless fruits.