Lettuce

Lettuce (Lactuca sativa var capitata )

The garden lettuce (Lactuca sativa ) is a plant of the genus lettuce (Lactuca ) in the sunflower family ( Asteraceae).

Description

It is a one-to two -year herbaceous plant that grows initially as a basic leaf rosette; this rosette or parts of it are the ones who are consumed by humans. The basal leaves are undivided or schrotsägeförmig, entire and not serrated thorny. In the summer schosst ( = it forms an inflorescence ) of garden salad finally in the air and reaches stature heights of 30 to 100 centimeters. The upright stem is paniculate - branched out, whitish, often mottled reddish in the upper part and bare. The stem leaves are heart-shaped - amplexicaul and usually obovate.

In paniculate inflorescences many small, narrow basket- shaped part inflorescences stand together. The basket- shaped partial inflorescences are approximately cylindrical shape, which swells during the flowering season, and its shell is made dachig arranged bracts, which have a length of about 8 to about 13 mm. The flower heads are usually seven to 15 (rarely up to 30 or more) ray florets present. The predominantly yellow sometimes a little purple color containing florets end in five corolla lobes, what can clearly be seen that the corolla tube is formed from five petals.

The depending on the variety -white, light gray, brown or black achenes are obovate and about 3 to 4 mm long, have one or more ribs, and often lead to a thread-like extended tip, where the pappus sitting. The white pappus consists of several rows of simple and equally long hair.

Ingredients

The ingredients are similar to those of other Latticharten, qv Cos ingredients. The garden salad makes a whitish milky sap, especially in the stems and inflorescences. This milky juice, from which also the botanical name Lactuca derived, contains bitter substances (see lettuce ) that help the plant in the defense against predators and pests; other hand, they also determine the palatability of its basal leaves.

An unwanted substance in the garden salad is among other nitrate. Dark -held garden salad can contain up to 4.85 grams per kilogram of nitrate plant. What matters is the ability to store nitrate, which is genetically determined and from variety to variety shows strong differences.

History

As ancestral species become the fence cos (Lactuca serriola ) was detected, one in southern Europe, the Middle East to northern India, and North Africa widespread steppe plant, with the garden salad is conspecific.

Since ancient times this plant is cultivated in many varieties. Thus, there exist 4500 years old reliefs, representing a plant that resembles the Roman salad. From Egypt starting, the salad over the whole ancient Greek and Roman world spread.

In Central Europe, the garden salad is spread only since the time of Charlemagne. Starting from the monastery gardens, the average salad spread (Lactuca sativa var crispa ) with its rosettes loose standing leaves, while in the Latin countries, the culture of the binding lettuce ( Lactuca sativa var longifolia ) has been developed with its elongated, a loose head -forming leaves. The now famous and popular lettuce (Lactuca sativa var capitata ) is a growth from the beginning of modern times.

Culture

Grown Salad flowers from June to August and the basal leaves develop but then too many bitter substances, so it is harvested before the lettuce growing in the height ( ' schosst ').

The main growing areas in Italy, France, Holland, Belgium, Spain and Germany belongs. In areas with frost the lettuce is grown under glass and in the open. Open-grown lettuce is offered up to 500 g in weight in the trade. The grown under glass are served from about 100 g. The winter salad from the greenhouse has higher average nitrate values ​​than the open-grown lettuce in the summer. This is due to the conditional in the greenhouse lack of light.

In the trade many salads come packed in foil to hold the head and at the same time to avoid excessive evaporation. The salad keeps the longer its freshness.

Others

By ethene the salad is wilted faster and gets brown spots. This gas flows from ripening fruit from about.

In addition to the green salad there is also a red variant. The color is caused by anthocyanins.

Cultural forms

The diversity of the cultivated forms can be divided into two main groups: the first has a short culture time and does not form a closed heads ( convar. sativa helmet), the second group with a long culture time is mostly heads ( convar. incocta helmet). In Hanelt names of the two groups " supergroup " 1 and 2, he assigns the following groups of varieties to:

• Supergroup 1 ( convar. sativa) Binding lettuce, romaine lettuce, Romaine ( Cos Group, Lactuca sativa var longifolia)
• Oilseed Group grown, because of the oil-bearing seeds
• Asparagus salad ( Stalk Group, Lactuca sativa var angustana )
• Sativa Group, only rarely, such as in Central Asia, cultivated

• Lettuce, green salad, butter lettuce ( butterhead Group, Lactuca sativa var capitata )
• Barney Salad ( Crisp Head Group ), including iceberg lettuce,
• Leaf lettuce, Lettuce, lettuce (Cutting Group, Lactuca sativa var crispa )
• Latin Group, forming thick, short leaves, common in the Mediterranean