Practical
Plants

Lactuca canadensis

Canada Lettuce

a biennial member of the Lactuca genus in the family Compositae.

No photo available

Taxonomy and growth

Genus
Lactuca
Life cycle
biennial
Height
3 m
Fertility
Insects
Flower type
hermaphrodite
Pollinators
Insects

Uses

Toxicity

Toxicity warning. The historical record reports a hazard for this plant. Do not use it to decide which parts are safe to eat or use medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

Although no specific mention of toxicity has been seen for this species, many plants in this genus contain a narcotic principle, this is at its most concentrated when the plant begins to flower. This principle has been almost bred out of the cultivated forms of lettuce but is produced when the plant starts to go to seed[3].

Edible uses

This section contains historical Plants For A Future notes marked noncommercial.

Young leaves and stems - raw or cooked[17][18][19][21][2][5]. Cooked and eaten as greens[13].

Plant part
Leaves

Medicinal uses

Historical medicinal uses. These records describe reported uses. They do not establish safety or effectiveness. Ask a qualified health professional before using any plant medicinally.

This section contains historical Plants For A Future notes marked noncommercial.

The whole plant is rich in a milky sap that flows freely from any wounds. This hardens and dries when in contact with the air[15]. The sap contains 'lactucarium', which is used in medicine for its anodyne, antispasmodic, digestive, diuretic, hypnotic, narcotic and sedative properties[22][8][17][4][6][7][9][10][12]. Lactucarium has the effects of a feeble opium, but without its tendency to cause digestive upsets[15], nor is it addictive[20]. It is taken internally in the treatment of insomnia, anxiety, neuroses, hyperactivity in children, dry coughs, whooping cough, rheumatic pain etc[12]. Concentrations of lactucarium are low in young plants and most concentrated when the plant comes into flower[12]. It is collected commercially by cutting the heads of the plants and scraping the juice into china vessels several times a day until the plant is exhausted[15]. An infusion of the fresh or dried flowering plant can also be used[22]. The plant should be used with caution, and never without the supervision of a skilled practitioner. Even normal doses can cause drowsiness whilst excess causes restlessness[12] and overdoses can cause death through cardiac paralysis[20][22]. Some physicians believe that any effects of this medicine are caused by the mind of the patient rather than by the medicine[9]. The sap has also been applied externally in the treatment of warts[10].

Product or use
Analgesic
Product or use
Diuretic
Product or use
Hypnotic
Product or use
Nervine
Product or use
Sedative
Product or use
Warts

Environment

Range
Eastern N. America - Nova Scotia to British Columbia, south to Georgia and Colorado.
Habitat
Thickets, woodland borders and clearings[16]. Moist open places[11]. Usually found in sandy soils[14].
Light
full sun
Shade tolerance
light shade
Water
moderate
Soil textures
sandy, loamy
Soil pH
acid, neutral, alkaline
Drainage
well drained
Tolerates Nutritionally Poor Soil
No
Drought
intolerant

Propagation

This section contains historical Plants For A Future notes marked noncommercial.

Seed - sow spring in situ and only just cover the seed. Germination is usually fairly quick.

Cultivation

This section contains historical Plants For A Future notes marked noncommercial.

Prefers a light sandy loam[1]. Hybridizes in the wild with L. ludoviciana and the two species can sometimes be difficult to separate[14].

References

  1. F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951-00-00

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  2. Tanaka. T. Tanaka's Cyclopaedia of Edible Plants of the World. Keigaku Publishing 1976-00-00

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  3. Triska. Dr. Hamlyn Encyclopaedia of Plants. Hamlyn 1975-00-00 ISBN 0-600-33545-3

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  4. Mills. S. Y. The Dictionary of Modern Herbalism.

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  5. Kunkel. G. Plants for Human Consumption. Koeltz Scientific Books 1984-00-00 ISBN 3874292169

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  6. Emboden. W. Narcotic Plants Studio Vista 1979-00-00 ISBN 0-289-70864-8

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  7. Coffey. T. The History and Folklore of North American Wild Flowers. Facts on File. 1993-00-00 ISBN 0-8160-2624-6

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  8. Lust. J. The Herb Book. Bantam books 1983-00-00 ISBN 0-553-23827-2

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  9. Weiner. M. A. Earth Medicine, Earth Food. Ballantine Books 1980-00-00 ISBN 0-449-90589-6

    ↩1↩2

  10. Foster. S. & Duke. J. A. A Field Guide to Medicinal Plants. Eastern and Central N. America. Houghton Mifflin Co. 1990-00-00 ISBN 0395467225

    ↩1↩2

  11. Britton. N. L. Brown. A. An Illustrated Flora of the Northern United States and Canada Dover Publications. New York. 1970-00-00 ISBN 0-486-22642-5

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  12. Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995-00-00 ISBN 0-7513-020-31

    ↩1↩2↩3↩4

  13. Moerman. D. Native American Ethnobotany Timber Press. Oregon. 1998-00-00 ISBN 0-88192-453-9

    ↩

  14. Diggs, Jnr. G.M.; Lipscomb. B. L. & O'Kennon. R. J Illustrated Flora of North Central Texas Botanical Research Institute, Texas. 1999-00-00 http://artemis.austincollege.edu/acad/bio/gdiggs/NCTXpdf.htm

    ↩1↩2

  15. Grieve. A Modern Herbal. Penguin 1984-00-00 ISBN 0-14-046-440-9

    ↩1↩2↩3

  16. Fernald. M. L. Gray's Manual of Botany. American Book Co. 1950-00-00

    ↩

  17. Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim 1959-00-00

    ↩1↩2

  18. Harris. B. C. Eat the Weeds. Pivot Health 1973-00-00

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  19. Usher. G. A Dictionary of Plants Used by Man. Constable 1974-00-00 ISBN 0094579202

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  20. Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984-00-00 ISBN 0-356-10541-5

    ↩1↩2

  21. Harrington. H. D. Edible Native Plants of the Rocky Mountains. University of New Mexico Press 1967-00-00 ISBN 0-8623-0343-9

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  22. Launert. E. Edible and Medicinal Plants. Hamlyn 1981-00-00 ISBN 0-600-37216-2

    ↩1↩2↩3

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