Collinsonia canadensis (L.)
Researcher: Tanner Filyaw

Common Names:
stone root
richweed
horsebalm
ox-balm
hardhack
heal-all
knob grass
knob root
citronella

Genus: Collinsonia L. 1808
(4 species) (16)

Family: Lamiaceae (77 general)
Sub-family — Nepetoideae, Tribe —
Mentheae (16)

Synonyms:
Collinsonia agustifolia Raf. 1828
Collinsonia canadensis L. var. cordata
Pursh (1814)
Collinsonia cuneata Wenderoth (1831)
Collinsonia decussata Moench (1794)
Collinsonia urticifolia Salisb. (1796) (20)

Relatives:
Collinsonia serotina
Collinsonia tuberosa
Collinsonia verticillata (23)

Duration:Perennial

Habit: erect Herb/Forb

Height: On average plants reach heights between 1 and 4 feet (8), but if conditions
are right they can reach up to 5 feet (15)

Stems: Stems are considered stout, erect,
and branching (8). When examined cross-sectionaly, Collinsonia stems are rounded
at the corners, and the xylem roughly
measures 1/8" of the cross sectional
thickness. A cross section of Collinsonia
is somewhat unique because it is rounded
at the corners, where as most members of the Lamiaceae retain their square shape internally. (15)


Collinsonia leaves -United Plant Savers
http://www.unitedplantsavers.org/

Leaves: Leaves are large, typically 6–8
inches long, and 3–4 inches wide (12),
opposite, oval shaped with a serrated
margin, and release a lemon scent when
crushed (21).


©Thomas G. Barnes. Barnes, T.G. &
S.W. Francis. 2004. Wildflowers and
ferns of Kentucky. University Press
of Kentucky. Usage Guidelines.

Flowers: Flowers are typically yellow,
small, roughly 1/3 – 1/2 inch long, hermaphroditic, arranged in a loose
panicle (21), and bloom from July to
September (8). Defining characteristics
of Collinsonia flowers are that they have
2 strongly protruding stamens that greatly
exceed the lip of the flower, and they
have an aromatic lemon scent. (19)

Fruit: Described as a nutlet containing 4
seeds that mature during autumn when the
plant begins to lose its leaves. (2)



Collinsonia root -United Plant Savers
http://www.unitedplantsavers.org/

Roots: The root of Collinsonia is
brownish to black in color, very dense,
knobby, and covered with a thick black
mat of fibrous roots (12). The tuber is
typically 4 inches long, and will almost
never exceed 7 inches in length (9).
Decreased tuber size is characteristic
of the Lamiaceae family, and in Collinsonia
it can be attributed to development and abundance of the secondary roots (9). According to Holm (1925) the secondary
root system begins to take over at the onset
of the 2nd season, causing the growth of the primary root to decrease (9). This
decrease in growth causes the spacing
of the basal internodes to become very
small, and in turn the tuber becomes very dense (12).

Seeds: Seeds of the Collinsonia mature in
the fall as the plant begins to lose its leaves. When mature, they are most likely dispersed
by wind (14), gravity (2), or both. Studies indicate that Collinsonia requires a period of cold stratification prior to the onset of germination (2). According to Albrecht and McCarthy (2006), Collinsonia seeds have a large functionally developed embryo upon maturity, suggesting that the period of cold stratification is only needed to facilitate germination, and is not needed for continued physiologic development within the seed (2).

Pollination: Based on research conducted at Rural Actions Research and Education Center (formerly Frontier Herbs Center for the Preservation of Medicinal Herbs), bumblebees and honey bees appeared to be the primary pollinators of this species.  When in bloom the cultivated beds would be alive with the buzz of hundreds of these insects (25). It is important to note that there is still a general lack of knowledge about the reproductive biology of many NTFP species, and further research is needed to help fill these gaps (5).

Habitat: Within its range C. canadensis favors moist woodlands with at least 60% canopy cover, and elevations less than 1500 ft. (14).  It prefers sites with light sandy to medium loam soils, and can tolerate a wider range of pH conditions. Although the species can tolerate a wide range of pH, it prefers to grow in a site with slightly acidic soils (21).

Range: C. canadensis is hardy to Zone 3 (3), can be found growing from Ontario south to Florida, and Missouri to Wisconsin (19), and has the widest distribution of all species within this genus (2)

Native: North America

Pests/diseases: None known

Other threats: According to the USFS populations of Collinsonia are threatened by the continued loss or alteration of habitats, and the increased construction of roads and trails. (14)

Conservation Status: Currently, about 1500 pounds are consumed annually in the Natural Products Industry. It is expected that this number will continue to rise as promising medicinal uses for this species continue to be found (25).  In the state of Wisconsin, C. canadensis is currently listed as an endangered species, and guidelines have been created to protect remaining populations (16).

History/Culture: The technical name, Collinsonia canadensis, was given to this plant in honor of the English merchant and botanist Peter Collinson (1693-1768), whom it is told, had an affinity for transporting and cultivating North American plants (12). The most common name, Stoneroot, was given to the plant by the Shakers, who were also the first known individuals to package the plant for commerce (12). At this time in Europe, the plant was not actually used medicinally, but has been used by Native Americans and early American settlers for a variety of conditions.  Most often the leaves of the plant were crushed, and then applied topically to cuts, bruises, ulcers, and ring worm (7).