Description: This native biennial or perennial plant
is about 1-2' tall, branching occasionally. The stems are glabrous and light
green; they are occasionally terrete (furrowed) or somewhat angular. The
alternate leaves are usually trifoliate, but some of the smaller upper leaves
are simple. The lower leaves often appear to be palmate, but this is because
each lateral leaflet has been deeply divided into 2 lobes. In outline, the
lower compound leaves are orbicular in shape (up to 5" wide and 5" across in
var. grandis, excluding the
petioles), while the upper compound leaves
are more narrow. The leaflets are obovate or ovate, coarsely toothed or cleft
along their margins, and hairless; when growing in the shade, they are usually
dark green. The lower leaves have long petioles, while the petioles of the
upper leaves are much shorter. The upper stems terminate in small umbels or
compound umbels of greenish white flowers. Each umbel consists of 1-4 umbellets
and spans up to 3" across. Each umbellet has 2-3 pistillate flowers and about
2-6 staminate flowers (less often, there will be 7-15 staminate flowers); these
flowers form a tight cluster that is globular and irregular. The perfect and
pistillate flowers are more conspicous because of their bur-like ovaries. Each
mature ovary (or fruit) is about 3-5 mm. in length and globular or subglobular
in shape; its outer surface is covered with hooked bristles. Each flower has 5
greenish white petals and a green calyx with 5 linear-oblong lobes. The petals
are shorter than the lobes of the calyx, while the latter are no longer than
the hooked bristles of the ovaries (1 mm. in length or less). The styles of
perfect and pistillate flowers are also shorter than the bristles. The blooming
period occurs from late spring to mid-summer and lasts about 3 weeks for a
colony of plants. There is no noticeable floral scent. Each bur-like fruit
contains 2 seeds. The root system is fibrous. This plant spreads by reseeding
itself and occasionally forms colonies.
Cultivation: The preference is light shade, moist to
slightly dry conditions, and a loamy soil with an abundance of organic
matter.
Range & Habitat:
Canadian Black Snakeroot is a common plant that occurs in nearly all counties
of Illinois (see
Distribution
Map). Habitats include mesic deciduous woodlands, north-facing bluffs,
areas along woodland paths, seeps, fence rows with woody vegetation, edges of
yards underneath trees, and flower gardens in shady areas. This plant occurs in
both natural habitats and disturbed areas.
Faunal Associations: The flowers attract few insect
pollinators, although occasionally they are visited by Halictid bees, Masked
bees, and Syrphid flies, which suck nectar. The species Hylaeus sanicula
(Sanicle Masked Bee) is an oligolectic visitor of Sanicula spp. The
bitter foliage is avoided by grazing livestock and probably other mammalian
herbivores as well. The small burs cling readily to the feathers of birds, fur
of mammals, and clothing of humans; this helps to distribute the seeds far and
wide.
Photographic Location: Underneath a lawn tree in
Urbana, Illinois. The photographed plant is var. grandis because of its
large leaves.
Comments: According to
Mohlenbrock (2003), plants with leaves exceeding 3" in length and 1½"
across are var. grandis, while plants with smaller leaves are the typical
variety; the latter is more common in Illinois. Canadian Black Snakeroot is not
very showy and begins to bloom after the deciduous trees in woodlands have
developed their leaves. Except for the bur-like ovaries, these flowers are
insignificant. This species is well-adapted to the shady conditions that exist
underneath trees during the summer, and can become a weed along the edges of
yards and in flower gardens. Except for Sanicula gregaria (Clustered
Black Snakeroot), which has greenish yellow flowers, the various Sanicula
spp. in Illinois have small greenish white flowers. The species of this
latter group are rather difficult to distinguish. Canadian Black Snakeroot
differs from Sanicula marilandica (Maryland Black Snakeroot) by its
short styles, which are no longer than the bristles of the fruit; the latter
species has a pair of curved styles at the apex of the fruit that are much
longer than the bristles. Canada Black Snakeroot differs from Sanicula
trifoliata (Large-Fruited Black Snakeroot) by the size and shape of its
fruit: Each fruit of the former is 3-5 mm. long and globuse or subglobose in
shape, while the fruit of the latter is at least 5.5 mm. in length and ovoid in
shape. Furthermore, the calyx lobes of the latter species are appressed
together and longer than the surrounding bristles, forming a beak-like shape at
the apex of each fruit.