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Lactuca sativa - L.

Lettuce

Author	L.	Botanical references	200
Family	Compositae	Genus	Lactuca
Synonyms
Known Hazards	The mature plant is mildly toxic[13].
Range	Of garden origin, probably derived from L. serriola.
Habitat	Not known in the wild.
Edibility Rating	3 (1-5)	Medicinal Rating	3 (1-5)

Physical Characteristics

Annual/Biennial growing to 0.9m by 0.25m.

The plant prefers light (sandy) and medium (loamy) soils and requires well-drained soil. The plant prefers neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It requires moist soil.

Habitats

Cultivated Beds;

Edible Uses

Edible Parts: Leaves; Seed.

Edible Uses: Oil.

Leaves - raw or cooked[7, 37]. A mild slightly sweet flavour with a crisp texture, lettuce is a very commonly used salad leaf and can also be cooked as a potherb or be added to soups etc[183]. A nutritional analysis is available[218]. Seed - sprouted and used in salads or sandwiches[183]. An edible oil is obtained from the seed[7]. The seed is very small, extraction of the oil on any scale would not be very feasible[K].

Composition

Figures in grams (g) or miligrams (mg) per 100g of food.

Leaves (Fresh weight)

• 0 Calories per 100g
• Water: 92.9%
• Protein: 2.1g; Fat: 0g; Carbohydrate: 3g; Fibre: 0.5g; Ash: 1.2g;
• Minerals - Calcium: 26mg; Phosphorus: 30mg; Iron: 0.7mg; Magnesium: 10mg; Sodium: 3mg; Potassium: 208mg; Zinc: 0mg;
• Vitamins - A: 2200mg; Thiamine (B1): 0mg; Riboflavin (B2): 0mg; Niacin: 0.4mg; B6: 0mg; C: 15mg;
• Reference: []
• Notes: 

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

Anaphrodisiac; Anodyne; Antispasmodic; Carminative; Diuretic; Emollient; Expectorant; Febrifuge; Galactogogue; Hypnotic; Hypoglycaemic; Narcotic; Parasiticide; Sedative.

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[4]. The sap contains 'lactucarium', which is used in medicine for its anodyne, antispasmodic, digestive, diuretic, hypnotic, narcotic and sedative properties[9, 21, 46, 165, 192, 213, 238]. Lactucarium has the effects of a feeble opium, but without its tendency to cause digestive upsets[4], nor is it addictive[7]. It is taken internally in the treatment of insomnia, anxiety, neuroses, hyperactivity in children, dry coughs, whooping cough, rheumatic pain etc[238]. Concentrations of lactucarium are low in young plants and most concentrated when the plant comes into flower[238]. 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[4]. The cultivated lettuce does not contain as much lactucarium as the wild species, most being produced when the plant is in flower[4]. An infusion of the fresh or dried flowering plant can also be used[9]. 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[238] and overdoses can cause death through cardiac paralysis[7, 9]. Some physicians believe that any effects of this medicine are caused by the mind of the patient rather than by the medicine[213]. The sap has also been applied externally in the treatment of warts[222]. The seed is anodyne and galactogogue[218]. Lettuce has acquired a folk reputation as an anaphrodisiac, anodyne, carminative, diuretic, emollient, febrifuge, hypoglycaemic, hypnotic, narcotic, parasiticide and sedative[218].

Other Uses

Hair; Parasiticide.

Parasiticide[178]. No further details are given, but it is probably the sap of flowering plants that is used. The seed is said to be used to make hair grow on scar tissue[218].

Cultivation details

Prefers a light sandy loam[1]. Succeeds in most well-drained, humus-rich soils but dislikes acid conditions[1, 16]. Plants strongly dislike dry conditions, quickly running to seed in such a situation. Early and late sowings are best in a sunny position, but summer crops are best given a position with some shade in order to slow down the plants tendency to go to seed and to prevent the leaves becoming bitter[18, 20]. The garden lettuce is widely cultivated in many parts of the world for its edible leaves and is probably the most commonly grown salad plant. There are many named varieties[183] capable of providing fresh leaves throughout the year if winter protection is given in temperate areas. Over the centuries a number of more or less distinct forms have arisen in cultivation. These forms have been classified as follows. They are treated separately in more detail:- L. sativa angustana. L.H.Bailey. is the Celtuce. The leaves of this form are not of such good quality as the other lettuces and the plant is grown more for its thick central stem which is used in the same ways as celery[1]. L. sativa capitata. L. is the heading lettuce, it forms a heart in a similar way to cabbages. Examples of this include the Iceberg and Butterhead lettuces. L. sativa crispa. L. is the curled or leaf lettuce. This does not form a central heart but produces a loose rosette of basal leaves. It can be harvested on a cut and come again basis. L. sativa longifolia Lam. is the cos lettuce. This has longer, thinner leaves and a more erect habit, it does not form a compact heart. Lettuces are quite a problematic crop to grow. They require quite a lot of attention to protect them from pests such as slugs, aphids and birds. If the weather is hot and dry the plants tend to run very quickly to seed, developing a bitter flavour as they do so. In wet weather they are likely to develop fungal diseases. In addition, the seed needs to be sown at regular intervals of 2- 3 weeks during the growing season in order to provide a regular supply of leaves. Lettuces make a good companion plant for strawberries, carrots, radishes and onions[18, 20, 201]. They also grow well with cucumbers, cabbages and beetroot[201].

Propagation

Seed - sow a small quantity of seed in situ every 2 or 3 weeks from March (with protection in cooler areas) to June and make another sowing in August/September for a winter/spring crop. Only just cover the seed. Germination is usually rapid and good, thin the plants if necessary, these thinnings can be transplanted to produce a slightly later crop (but they will need to be well watered in dry weather). More certain winter crops can be obtained by sowing in a frame in September/October and again in January/February.

Cultivars

There are many named varieties of this annual vegetable, with new forms being developed each year. At present there is not time to enter these in the database and it is recommended that you consult the book 'The Fruit and Vegetable Finder' which is updated regularly and can be obtained from libraries.

Links

References

[K] Ken Fern
Notes from observations, tasting etc at Plants For A Future and on field trips.

[1] F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaces in 1992 by a new dictionary (see [200]).

[4] Grieve. A Modern Herbal. Penguin 1984 ISBN 0-14-046-440-9
Not so modern (1930's?) but lots of information, mainly temperate plants.

[7] Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984 ISBN 0-356-10541-5
Covers plants growing in Europe. Also gives other interesting information on the plants. Good photographs.

[9] Launert. E. Edible and Medicinal Plants. Hamlyn 1981 ISBN 0-600-37216-2
Covers plants in Europe. a drawing of each plant, quite a bit of interesting information.

[13] Triska. Dr. Hamlyn Encyclopaedia of Plants. Hamlyn 1975 ISBN 0-600-33545-3
Very interesting reading, giving some details of plant uses and quite a lot of folk-lore.

[16] Simons. New Vegetable Growers Handbook. Penguin 1977 ISBN 0-14-046-050-0
A good guide to growing vegetables in temperate areas, not entirely organic.

[18] Philbrick H. and Gregg R. B. Companion Plants. Watkins 1979
Details of beneficial and antagonistic relationships between neighbouring plants.

[20] Riotte. L. Companion Planting for Successful Gardening. Garden Way, Vermont, USA. 1978 ISBN 0-88266-064-0
Fairly good.

[21] Lust. J. The Herb Book. Bantam books 1983 ISBN 0-553-23827-2
Lots of information tightly crammed into a fairly small book.

[37] Thompson. B. The Gardener's Assistant. Blackie and Son. 1878
Excellent general but extensive guide to gardening practices in the 19th century. A very good section on fruits and vegetables with many little known species.

[46] Uphof. J. C. Th. Dictionary of Economic Plants. Weinheim 1959
An excellent and very comprehensive guide but it only gives very short descriptions of the uses without any details of how to utilize the plants. Not for the casual reader.

[165] Mills. S. Y. The Dictionary of Modern Herbalism. 0
An excellent small herbal.

[178] Stuart. Rev. G. A. Chinese Materia Medica. Taipei. Southern Materials Centre 0
A translation of an ancient Chinese herbal. Fascinating.

[183] Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications 1990 ISBN 0-9628087-0-9
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.

[192] Emboden. W. Narcotic Plants Studio Vista 1979 ISBN 0-289-70864-8
A lot of details about the history, chemistry and use of narcotic plants, including hallucinogens, stimulants, inebriants and hypnotics.

[200] Huxley. A. The New RHS Dictionary of Gardening. 1992. MacMillan Press 1992 ISBN 0-333-47494-5
Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.

[201] Allardice.P. A - Z of Companion Planting. Cassell Publishers Ltd. 1993 ISBN 0-304-34324-2
A well produced and very readable book.

[213] Weiner. M. A. Earth Medicine, Earth Food. Ballantine Books 1980 ISBN 0-449-90589-6
A nice book to read though it is difficult to look up individual plants since the book is divided into separate sections dealing with the different medicinal uses plus a section on edible plants. Common names are used instead of botanical.

[218] Duke. J. A. and Ayensu. E. S. Medicinal Plants of China Reference Publications, Inc. 1985 ISBN 0-917256-20-4
Details of over 1,200 medicinal plants of China and brief details of their uses. Often includes an analysis, or at least a list of constituents. Heavy going if you are not into the subject.

[222] Foster. S. & Duke. J. A. A Field Guide to Medicinal Plants. Eastern and Central N. America. Houghton Mifflin Co. 1990 ISBN 0395467225
A concise book dealing with almost 500 species. A line drawing of each plant is included plus colour photographs of about 100 species. Very good as a field guide, it only gives brief details about the plants medicinal properties.

[238] Bown. D. Encyclopaedia of Herbs and their Uses. Dorling Kindersley, London. 1995 ISBN 0-7513-020-31
A very well presented and informative book on herbs from around the globe. Plenty in it for both the casual reader and the serious student. Just one main quibble is the silly way of having two separate entries for each plant.

Readers Comments

Plants for a Future does not verify the accuracy of reader comments, use at your own risk. In particular Plants For A Future can not take any responsibility for any adverse effects from the use of plants. You should always consult a professional before using plants medicinally.

Lactuca sativa

karoline Tue Jan 20 2009

sir, i want the detail lettuce seed production.

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