Lettuce (Garden Lettuce, Cultivated Lettuce)

Lettuce (Garden Lettuce, Cultivated Lettuce)
Lactuca sativa L.
Family Compositae (Asteraceae) — Compositae (Asteraceae)

Description of Lettuce

Garden lettuce (Lettuce, cultivated lettuce) is an annual herbaceous plant, 30–150 cm tall. It forms a basal rosette of sessile leaves, sometimes closing into a loose head (40–180 g). The leaves are broadly ovate, 10–30 cm, soft, smooth, wavy, curly, ruffled, or wrinkled, green or reddish, with the blade tapering down the petiole. The flowering stem is furrowed, densely leafy, branched at the top. Stem leaves are toothed, petiolate at the base, rounded-obovate or elliptical, higher up — small, sessile, stem-clasping, often rounded-reniform. Flowers are light yellow, small, in capitula, gathered into a corymbose-paniculate inflorescence; involucres 3–4-rowed, not reflexed upon ripening. Fruits are flattened, ribbed achenes, narrowly obovate, 3–4 mm, black, gray, brown, or white, with a filiform beak and a pappus of soft white hairs. Varieties: Leaf lettuce (succulent, tender leaves), Head lettuce ('Iceberg', var. capitata L.), 'Romaine', 'Lollo Rosso', 'Butterhead' (e.g., 'Bibb', 'Boston'), 'Oakleaf'. Flowering in June–August, fruiting in July–September.

 

Habitat and Ecology of Lettuce

The homeland of lettuce is the Mediterranean. Wild species are found in Western Europe, North Africa, Western Asia. It is cultivated in Europe, Asia, America, Australia in open and protected ground. It prefers loose, moist soils (pH 6.0–7.0), temperatures of 15–20 °C, watering 10–15 l/m² every 4–6 days, and does not tolerate heat above 30 °C. Propagates by seeds (sowing in March–May). Yield: leaves — 2–4 kg/m²; seeds — 0.3–0.5 kg/m². Care: weeding, nitrogen fertilization (10–15 g/m²), protection from slugs and aphids. Environmentally improves soil, used in crop rotation after legumes.

 

Raw Materials from Lettuce

Raw materials: fresh leaves (folia Lactucae sativae), seeds (semen Lactucae sativae), milky sap (latex Lactucae). Leaves are harvested in May–July before flowering, dried at 30–35 °C (yield 10–15%). Seeds are harvested in July–September, dried at 25–30 °C (yield 90–95%). Milky sap is collected from stems in June–August, dried at 40 °C (yield 5–10%). Quality: leaves — green, without spots; seeds — gray, moisture ≤12%; sap — white, bitter. Store in airtight containers (leaves: 6 months; seeds: 2 years; sap: 1 year). Herbal odor, bitter taste.

 

Chemical Composition of Lettuce

Leaves contain: ascorbic acid (10–20 mg%), β-carotene (1.5–2 mg%), vitamins (B1 up to 0.05 mg%, B2, B6 up to 0.18 mg%, PP up to 0.65 mg%, K, P, folic acid up to 0.1 mg%, pantothenic acid up to 0.1 mg%, biotin, tocopherols up to 0.66 mg%), organic acids (citric, malic, oxalic, succinic), sugars (2–4%), easily digestible proteins, minerals (Fe up to 600 mg%, Ca, K, Mg, P, I, Co, Cu, Zn), lactucin, lactucerin, lactucictin (in milky sap, 0.01–0.02%). Seeds: fatty oil (20–30%, linolenic, oleic acids). Calorie content of leaves: 12–15 kcal/100 g.

 

Action and Application of Lettuce

Lettuce has sedative, diuretic, choleretic, hematopoietic, and analgesic effects. It is used for insomnia, hypertension, neurasthenia, psychomotor agitation, chronic gastritis, stomach and duodenal ulcers, anemia (normo- and hypochromic), gout, urate and oxalate kidney stones, obesity, diabetes mellitus, thyroiditis, thyrotoxicosis, bronchitis, edema, whooping cough. Leaves normalize fat-lipid and water-salt metabolism, strengthen blood vessels, increase body tone, stimulate hematopoiesis. Milky sap relieves pain, reduces reflex and motor excitability, acts as a mild sedative; in ancient times it was used as a sobering agent. The sap is effective for gastritis, edema, increased excitability. Seed infusion enhances lactation. Externally, the sap is used for burns, skin irritations. The flowering plant is used in homeopathy.

 

Precautions for Lettuce Use

Excessive consumption of leaves (over 200 g/day) or sap (over 50 ml/day) may cause drowsiness, nausea. Store raw materials at humidity ≤12%. For children under 3 years, give ≤30 g/day of leaves. Avoid combination with anticoagulants (due to vitamin K). Seeds (over 5 g/day) may excessively increase lactation.

 

Contraindications for Lettuce Use

Acute hepatitis, cholecystitis, urolithiasis with large stones, allergy to Asteraceae, hypotension.

 

Recipes with Lettuce

1. Infusion for insomnia. Pour 200 ml of boiling water over 20 g of finely chopped leaves, let infuse until cooled, drink 100 ml 1–1.5 hours before bedtime, for 7 days.
2. Juice for anemia. Drink 50 ml of juice twice a day, for 10 days.
3. Seed infusion for lactation. Pour 100 ml of boiling water over 5 g of seeds, let infuse for 2 hours, drink 50 ml twice a day, for 5 days.
4. Compress for burns. Apply 20 g of milky sap to the skin for 15 minutes, rinse, twice a day, for 3 days.
5. Lettuce and Cucumber Salad. Mix 100g chopped lettuce, 1/2 sliced cucumber, 2 tablespoons olive oil, a squeeze of lemon juice, salt, and pepper.
6. Lettuce and Avocado Smoothie. Blend 50g lettuce, 1/2 avocado, 100ml almond milk, and a teaspoon of honey until smooth.

 

Lettuce in Cosmetics

Lettuce is used for skin care.

1. Mask for skin freshness. Mix 20 g of crushed leaves with 10 g of sour cream, apply for 15 minutes, rinse, twice a week.
2. Lotion for oily skin. Mix 30 ml of juice with 5 ml of lemon juice, wipe the skin, once a day.
3. Mask for irritations. Mix 20 g of crushed leaves with 10 ml of olive oil, add 3–5 drops of lemon juice, apply for 20 minutes, rinse with hot, then cold water, twice a week.
4. Facial tonic. 50 ml of juice, 10 ml of water, wipe the skin, twice a day.
5. Soothing Eye Compress. Soak cotton pads in chilled lettuce juice and place on closed eyelids for 10-15 minutes to reduce puffiness.

 

Lettuce in Cooking

Leaves are used fresh before flowering, boiled, stewed, or fried. Fresh leaves are thoroughly washed, damaged and tough veins are removed, and then dried. For salads, the core is cut into strips, spices, green onions, dill, salt, and finely chopped onions are added. The sides of the dish are rubbed with garlic; sauce (fruit juice, lemon, vinegar, buttermilk, sour cream, vegetable oil, sugar) is added before serving. Head lettuce (var. capitata L.) is tied with string before boiling to prevent the head from falling apart.

1. Salad with sour cream and onion. 100 g leaves, 30 g green onion, 10 g dill, 20 g sour cream, salt, mix.
2. Salad with egg. 100 g leaves, 1 boiled egg, 10 ml sunflower oil, vinegar, salt, mix.
3. Stewed lettuce. Stew 150 g leaves with 10 ml oil for 5 minutes, add salt, garlic.
4. Smoothie. 50 g leaves, 100 ml apple juice, 10 g honey, blend.
5. Grilled Romaine Halves. Halve a head of Romaine lettuce, brush with olive oil, salt, and pepper, then grill cut-side down for 2-3 minutes until slightly charred. Serve with a balsamic glaze.
6. Lettuce Wraps with Chicken. Use large, crisp lettuce leaves (like Iceberg or Butterhead) as wraps for a filling of sautéed ground chicken, water chestnuts, and a savory sauce.

Tips: Store leaves in the refrigerator at 2–5 °C for no longer than 5 days, use sunflower or soybean oil for dressing.

 

Other properties of lettuce

Lettuce improves soil and is used in crop rotation. Leaves are used as animal feed.