Description: This native perennial plant is
1½–3½' tall, branching occasionally. The stems are light
green or light reddish green, glabrous, and glaucous. The compound leaves are
up to 1' long and 6" across (excluding their petioles), becoming smaller as
they ascend the stems; they are alternate, green, and glabrous. The lower
leaves are doubly pinnate, while the upper leaves are often simple-pinnate. The
petioles of the lower leaves are long, while those of the shorter leaves are
much shorter or absent. The leaflets are up to 3" long and 1/3" across; they
are linear to lanceolate-linear, dentate, and sometimes cleft
into narrow lobes.
The axils of the upper leaves often have sessile clusters of ovoid bulblets.
The upper stems terminate into compound umbels of small white flowers. Each
compound umbel spans about 2-4" across and consists of about 8 umbellets. Each
umbellet has about 16 flowers. There are neither bracts nor bractlets at the
base of the compound umbel and its umbellets, although a small sessile leaf may
occur near the base of the compound umbel. Each flower spans about 1/8" across
and consists of 5 white petals, 5 stamens, 2 styles, and an ovary. The blooming
period occurs during late summer to early fall and lasts about a month. There
is no noticeable floral scent. Each seed is contained in a fruit about 1/8"
long that is somewhat flattened, ovoid-oblongoid, and slightly notched at its
apex. The root system consists of a cluster of elongated fleshy roots. The
foliage, seeds, and fleshy roots are toxic (especially the latter). This plant
reproduces by its seeds and bulbets.
Cultivation: The preference is light shade to full
sun, wet conditions, and a mucky or mossy soil. This plant requires soil that
is saturated with moisture throughout the year.
Range & Habitat: Bulblet-Bearing Water Hemlock
is an uncommon plant that occurs primarily in the northern half of Illinois,
especially in the NE area of the state (see
Distribution
Map). Habitats include marshes, swamps, and borders of lakes and ponds.
This species is normally found in high quality wetlands.
Faunal Associations: Like other members of the
Carrot family, the nectar of the flowers is accessible to insects with short
mouthparts and will attract such visitors as flies, wasps, beetles, and small
bees. Some of these insects may collect or feed on the pollen as well. The
caterpillars of the butterfly Papilio polyxenes asterias (Black
Swallowtail) feed on the foliage. The poisonous seeds are not eaten by birds,
while the poisonous foliage and roots are usually avoided by mammalian
herbivores. Consumption of the fleshy roots and other parts of this plant by
humans can cause convulsions and death.
Photographic
Location: A marsh in Vermillion County, Illinois.
Comments: Bulblet-Bearing Water Hemlock is highly
unusual because it bears clusters of bulblets in the upper leaf axils. I can
think of no other plant in Illinois that has this characteristic. Some
Allium spp. (Onions) produce bulblets instead of flowers in their
umbels, but their bulblets are not produced from the axils of leaves. Another
species that occurs in the state, Cicuta maculata (Water Hemlock) is
more common. Water Hemlock is a larger plant than Bulblet-Bearing Water Hemlock
and it has broader leaflets (more than 1/3" across). Water Hemlock blooms
during mid-summer before Bulblet-Bearing Water Hemlock begins to bloom. Another
white-flowered member of the Carrot family, Sium suave (Water Parsnip),
often blooms at the same time as Bulblet-Bearing Water Hemlock and it occurs in
the same wetland habitats. Water Parsnip has 3 lanceolate bracts at the base of
its compound umbels and its leaves are always simple-pinnate. Another similar
species that blooms late, Oxypolis rigidior (Cowbane), also has leaves
that are simple-pinnate. In contrast, the lower leaves of Bulblet-Bearing Water
Hemlock are doubly pinnate.