Practical
Plants

Lactuca pulchella

Blue Lettuce

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Taxonomy and growth

Genus
Lactuca
Life cycle
perennial
Height
1 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.

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[2].

Edible uses

Young leaves - raw or cooked[17][8]. A gum obtained from the roots is used for chewing[3][5][8][13].

Product or use
Gum
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.

An infusion of the roots and stems has been given to children in the treatment of diarrhoea[13]. A poultice of the plants has been applied to piles[13]. Although we have seen no other specific reports for this species, most if not all members of the genus have a milky sap that contains the substance 'lactucarium' and can probably be used as the report below details[K]. 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[14]. The sap contains 'lactucarium', which is used in medicine for its anodyne, antispasmodic, digestive, diuretic, hypnotic, narcotic and sedative properties[18][7][15][4][6][9][12]. Lactucarium has the effects of a feeble opium, but without its tendency to cause digestive upsets[14], nor is it addictive[16]. 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[14]. An infusion of the fresh or dried flowering plant can also be used[18]. 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[16][18]. 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
Astringent
Product or use
Poultice

Environment

Range
N. America - Alaska to Minnesota, south to Missouri, New Mexico and California.
Habitat
Medium-dry to moist soils in fields, thickets of prairies, valleys and in mountains to 2,100 metres[8].
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

Seed - sow April in a greenhouse, only just covering the seed. Germination is usually fairly quick. Prick out the seedlings into individual pots when large enough to handle and plant them out in the summer. Division in spring. Root cuttings in spring[K].

Cultivation

Prefers a light sandy loam[1]. This species is considered to be a noxious weed in N. America where it spreads freely by suckers in cultivated ground - even a small portion of the root can regenerate to form a new plant[8].

References

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

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

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  3. Yanovsky. E. Food Plants of the N. American Indians. Publication no. 237. U.S. Depf of Agriculture.

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

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  8. Craighead. J., Craighead. F. and Davis. R. A Field Guide to Rocky Mountain Wildflowers The Riverside Press 1963-00-00 ISBN 63-7093

    ↩1↩2↩3↩4

  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

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  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

  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

    ↩1↩2↩3

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

    ↩1↩2↩3

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

    ↩

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

    ↩1↩2

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

    ↩1↩2↩3

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