Pointer plants (indicator plants) are plant species with a low ecological potency , i.e. with a low tolerance to changes in their living conditions. They therefore give, among other things, good information on the nature of the subsoil and soil on which they grow, on the climatic conditions or on the entry of air pollutants, and thus belong to the so-called bio - indicators . The pointer values according to Ellenberg give a detailed classification of various location parameters .
The pointer value of wild-growing plants was scientifically described for the first time by the agricultural scientist Georg Ernst Wilhelm Crome , who describes them in his book The Soil and Its Relationship to the Vegetables , published in 1812 . Pointer plants were named in the agricultural economic advisory literature such as the house fathers literature in the 17th century. Woods in particular were identified as indicators of soil quality. For example, Wolf Helmhardt von Hohberg wrote in Georgica curiosa (1695 ): “The most certain sign of a fruity soil [is] / when the field, forest and garden trees are high and rich in aesthetics / especially where wild pear, apple and cherries - and other fruit trees grow and spread by themselves. ”Prior to the scientific description, there was knowledge based on experience and tradition about the bioindicative properties of plants.
The ecological value of pointer plants for agriculture and landscape maintenance was only "rediscovered" and systematically researched by science in the second half of the 20th century, especially by the geobotanist Heinz Ellenberg . When doing research, it is important that the connections between soil reaction and plant growth must be checked on a wide variety of locations in order not to obtain a result that is too specific and too narrow.
Phenological indicator plants are called plants which herald the ten physiologically and biologically based " phenological seasons " (e.g. the beginning of flowering of the black elder in early summer, the beginning of flowering of the summer linden tree in midsummer).
- Nitrogen- rich soil ( nitrophytes ): stinging nettle , burdock bedstraw , melde , chickweed , buttercup , black elder , common dandelion , blackberry
- Nitrogen-poor soil: spicy stonecrop
- Sour soil: Common heather , soft honeydew grass , sorrel , bilberry
- Basic (or alkaline) Soil: Ordinary Pechnelke , Real Wundklee
- Calcareous soil: pasque flower , field delphinium
- Moist soil: cabbage thistle , globe flower
- Waterlogging: field horsetail , field mint , coltsfoot
- Salt soil ( salt plants ): samphire
- Sandy soil: sand sedge
- Compacted soil: plantain , creeping buttercup , couch grass , fingerweed
- Heavy metal containing soil ( metallophytes ): Galmeiflora , heavy metal lawn
- Light pointer: yellow sun rose
- Shadow pointer: Wood sorrel
- Heinz Ellenberg among others: Pointer values of plants in Central Europe. 3. Edition. Goltze, Göttingen 2001, ISBN 978-3-88452-518-0 .
- Wolfgang Licht: Pointer plants. Recognize and determine. 1st edition. Quelle & Meyer Verlag, Wiebelsheim 2013, ISBN 978-3-494-01508-8 .
- Ulrike Kruse: The nature discourse in house fathers literature and folk educational writings from the late 16th to the early 19th century. Edition Lumière, Bremen 2013, ISBN 978-3-943245-07-3 .
- Wolf Helmhardt von Hohberg: Georgica Curiosa Aucta, That is: Complicated report and clear teaching of the aristocratic country and field life. Directed at all farms and domestic establishments customary in Germany . Volume 2. Nuremberg 1695 , p. 13.