Lactuca serriola
Spiked lettuce (Lactuca serriola )
The sting - lettuce (Lactuca serriola ), also compass cos or romaine lettuce called Fence, belongs to the sunflower family ( Asteraceae).
Description
The sting cos is an annual or biennial herbaceous plant wintering, reaches the heights of growth from 30 to 120 cm. You can hit up to two meters deep roots. The plant carries out a white milky sap.
The alternate on the stem leaves are often distributed vertically, often after north-south pointing ( " compass plant" ). The leaves are deeply sinuate lobed ( type Form: format serriola ) or lanceolate and unlobed ( forma integrifolia ), the leaf margin is serrated always more or less coarse. The spines on the midrib are longer than their mutual distance.
At one plant are many basket- like inflorescences. The flower heads contain only 12 to 20 florets. The petals are fused crowded yellow and purple unequal. The light gray -brown achenes are rough and about 2.5 to 3.5 mm long, with a white, (3 to ) 4 to 5 mm long pappus.
It flowers from July to September.
The chromosome number is 2n = 18
Dissemination and locations
The distribution area of the sting cos ranges in north-south direction from Ethiopia and the Mediterranean to the north up to the Temperate Zone; there, the deposits are concentrated in lowland areas and heat. In west-east direction, the distribution area of the Atlantic Islands to Mongolia, Xinjiang ranges in western China, Afghanistan and North India. He was introduced in southern Africa in East Asia, Australia, New Zealand, North America and southern South America.
The sting cos often comes in sunny, premolars weed corridors, roadsides, rubbish and debris spots, most in rail and loading facilities, on walls, embankments and hedges. He prefers dry, nutrient-rich soils in warm, sunny locations.
After Ellenberg he is a full- light plant, a heat indicator, and a Verbandscharakterart ruderal annuals in temperate warm climate ( Sisymbrion ).
System
Lactuca serriola was first published in 1756 by Carl Linnaeus in Centuria II Plantarum. An important 1763 posted synonym is scariola Lactuca L.
The sting cos is the parent plant our garden lettuce (Lactuca sativa). Genetic studies show so many similarities between the cultural form Lactuca sativa and wild-type Lactuca serriola that splitting into two species do not appear to be justified.
The shape of the stem leaves of Lactuca serriola serriola f and f integrifolia (SF Gray) SD Prince & RN Carter is hereditary and not connected by transitions. Plants with both leaf shapes are frequently occurring regionally, before but sometimes side by side on the same growing area.
Ecology
This type has a strong adaptation to drought and sunlight: Leaves in sunny spots are located in " compass " position: The leaf blade is vertical, its narrow side is oriented in a north-south direction, parallel to the sunlight. Thus, the leaf blades are fully exposed to less intense sunlight of the morning and afternoon. During mid-day sun peaking but have opposed all the edges of the sun.
Because of the barbed lettuce has differences in leaf orientation depending on location, is likely a tropism present here. In the shadow standing plants namely show no such alignment of the leaf blades, it can even happen on the hillside that the shaded leaves are oriented horizontally, but have the sunlit leaves the vertical north-south direction.
The reorientation of the leaf blade comes with compass plants established through growth and torsional movement of the petiole. Therefore, the Spreitenstellung remains after completion of growth.
Pollination of flowers carried by insects, also self-pollination takes place.
Predators and parasites
The sting cos is the food plant for the Kompasslatticheule ( Hecatera dysodea ) and for the cos - monk ( Cucullia lactucae ). While the caterpillars of the Kompasslatticheule green to light brown are rather unimpressive showing the caterpillars of Cos monk a striking white-yellow- black color.
The following fungi parasitize on the sting cos, namely the mildew species Erysibe cichoracearum, Sphaerotheca fusca and Bremia lactucae and the two rust fungi Puccinia opizii ( with change of host on sedges ) and Puccinia maculosa (without host change).