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The flora is complex and some plants are designed differently to the natural conditions than others. A good example of this are the so-called indicator or pointer plants, which provide information about the quality and properties of the soil. Just by their presence, they reveal whether the soil is alkaline, moist or humus-rich and thrive poorly in soils of a different condition.
Explanation of terms: indicator plants
Indicator plants can be seen as examples of soil conditions. These are special species that have a certain ecological tolerance. Ecological tolerance or potency describes how well the species tolerates changes in location. These include the following:
- soil condition
- Amount of soil, air or water pollutants
- amount of light
A pointer plant is therefore nothing more than a bio-indicator that can show you how the location or the immediate environment affects it. If the condition changes from one day to the next, this has a negative effect on the plant, since its tolerance for the new properties is not high enough.
This is exactly why indicator plants are so important, because they can be used to give initial information about the soil or location. For example, after purchasing a piece of land, you can examine the plants in the garden and get a rough idea of what kind of soil you are dealing with. A precise analysis is then usually easier.
Tip: In addition to the actual indicator plants, there are also the "phenological indicators" that do not reveal the possible soil conditions, but provide information about the biological seasons.
Urtica dioica
100 indicator plants presented
There are numerous examples of indicator plants, as there are a large number of different locations and soil conditions in Central Europe. These range from acidic to nutritious to salty, resulting in multiple bioindicators being available for these particular properties. While some plant species occur exclusively on certain soils and show this by their presence, others occur on several or a mixture of different soil types.
Due to this problem, the individual properties must be examined more closely. In the following sections, you will be introduced to the corresponding types of plants, the grouping of which usually tells you exactly which properties are desired from the soil.
Alkaline soils
1. Field mustard (Sinapis arvensis)
2. Nodding thistle (Carduus nutans)
3. Germander Speedwell (Veronica chamaedrys)
4. Common pitcher (Silene viscaria)
5. kidney vetch (Anthyllis vulneraria)
Calcareous soils
6. Alpine rose (Rhododendron hirsutum)
7. Hollow Corydalis (Corydalis cava)
8. Mezereon (Daphne mezereum)
9. Pasque flower (Pulsatilla vulgaris)
10. Larkspur (Consolida regalis)
Consolida regalis
nitrogen
The subject of nitrogen is important, as there are indicator plants for particularly high amounts of nitrogen (nitrogen indicators) and those that only thrive on soil that is low in nitrogen. The Nitrogen Gauges (Nitrophytes) are common and the following list will introduce you to a few:
11. Field mint (Mentha arvensis)
12. Field bindweed (Convolvulus arvensis)
13. Nettle (Urtica dioica)
14. Sonchus (Sonchus)
15. Black elder (Sambucus nigra)
16. Red Elder (Sambucus racemosa)
17. Blackberries (Rubus)
18. Balsam (Impatiens parviflora)
19. Balsam (Impatiens noli-tangere)
20. Creeping thistle (Cirsium arvense)
Low-nitrogen soils, on the other hand, are only preferred by a few plants:
21. Hot Stonecrop (Sedum acre)
22. Hairy Rattle (Rhinanthus alectorolophus)
23. Hunger flowers (Draba verna)
24. Scentless Chamomile (Tripleurospermum inodorum)
Sedum acre
Tip: In addition to the indicators for increased and reduced nitrogen levels, there are numerous plants that love nitrogen. Many plant species prefer nitrogen, but do not depend on large amounts and are therefore not reliable enough as indicator plants, such as mugwort (bot. Artemisia vulgaris).
Acid soils
The blueberry (bot. Vaccinium myrtillus) is one of the best-known plants that thrive in acidic soil. The low pH is also good for other plants:
25. Common heather (Calluna vulgaris)
26. Field Sparrow (Spergula arvensis)
27. Honeygrass (Holcus lanatus)
28. Dog Chamomiles (Anthemis)
29. Daisy (Bellis perennis)
30. Meadow daisy (Leucanthemum vulgare)
potassium indicator
31. Bear Claw (Heracleum)
32. Foxglove (Digitalis purpurea)
33. Lying Pearlwort (Sagina procumbens)
Heracleum mategazzianum
humic soils
34. Great Brunelle (Prunella grandiflora)
35. Ground elder (Aegopodium podagraria)
36. Dead Nettles (Lamium)
37. Nettles (Urtica)
38. Ragwort (Senecio vulgaris)
39. Meadow vetchling (Lathyrus pratensis)
40. Chickweed (Stellaria media)
sandy soils
One of the most well-known indicator plants for sandy soils is the pine (bot. Pinus). But these are not the only plants that get along very well with sandy soils. They are not dependent on a lot of moisture and can even cope with the fairly high heat development. Many of the sandy soil plants often get along with rock gardens.
41. Viper Bugloss (Echium vulgare)
42. Sand sedge (Carex arenaria)
43. Hare clover (Trifolium arvense)
44. Wild carrot (Daucus carota subsp. carota)
45. Lesser Sorrel (Rumex acetosella)
46. Wild thyme (Thymus serpyllum)
47. Sand poppy (Papaver argemone)
48. Corn poppy (Papaver rhoeas)
Papaver rhoeas
clay soils
In loamy soils, there are a large number of indicator plants that prefer different loamy locations. The typical clay soils are classified as follows:
- Clay soils with a high sand content
- clayey and loamy
- nutritious and fresh (mostly humus-loamy)
Because of this, the boundaries between indicator plants are sometimes blurred. However, there are some that always pop up with clayey soils:
49. Creeping thistle (Cirsium arvense)
50. Field pansy (Viola arvensis)
51. Common fumitory (Fumaria officinalis)
52. Persian Speedwell (Veronica persica)
53. Rayless chamomile (Matricaria discoidea)
54. Mulleins (Verbascum)
55. Knotweed (Polygonum aviculare)
Verbascum phlomoides
Tip: Clay soils are not considered compacted until moisture is high. In this case, the soil is moist and heavy, which quickly leads to compaction, but cannot be directly equated with loamy soil.
Compacted soils
56. Broad plantain (Plantago major)
57. Couch Grass (Elymus repens)
58. Comfrey (Symphytum)
59. Cleavers (Galium aparine)
60. Creeping Buttercup (Ranunculus repens)
61. Dandelion (Taraxacum)
62. Lesser Celandine (Ficaria verna)
63. Marsh Ziest (Stachys palustris)
64. Meadow knotweed (Polygonum bistorta)
dryness
65. Little burnet (Pimpinella saxifraga)
66. Field hollow tooth (Galeopsis ladanum)
67. Red Millet (Digitaria sanguinalis)
68. Dyer's Chamomile (Cota tinctoria)
69. White Campion (Silene latifolia)
70. Heron's Beaks (Erodium)
71. Falcaria vulgaris (Falcaria vulgaris)
72. Summer Adonis (Adonis aestivalis)
73. Cranesbills (Geranium)
Adonis estivalis. Source: Zeynel Cebeci, Adonis aestivalis - Kandamlası 02, crop from Plantopedia, CC BY-SA 4.0
Moist soils to waterlogging
This type of soil needs a closer look. Compared to waterlogging, damp to wet soils are not permanently submerged in water. Moisture can be drawn off or distributed regularly, which benefits the roots or perennial organs. Indicator plants for moist to wet soil include:
74. Cabbage thistle (Cirsium oleraceum)
75. Globeflower (Trollius europaeus)
76. Common prunella (Prunella vulgaris)
77. Ivy Speedwell (Veronica hederifolia)
78. Meadowsweet (Filipendula ulmaria)
Waterlogging, on the other hand, is presented by the following plants, which can easily grow and thrive in these conditions:
79. Sorrel knotweed (Persicaria lapathifolia)
80. Coltsfoot (Tussilago farfara)
81. Field horsetail (Equisetum arvense)
82. Cinquefoil (Potentilla anserina)
83. Great burnet (Sanguisorba officinalis)
Equisetum arvense
Notice: Indicator plants for groundwater-permeated soils can also be integrated into this category, including nettles, hops, groundweed, the meadow bittercress and the red campion. Whether the soil is really permeated by groundwater can only be seen with a test, especially with these plants.
shadow and light pointers
As the names make clear, these terms describe plant species that prefer either lots of light (light pointers) or shade (shade pointers). Since a soil with permanent shade has a completely different coating than sun-soaked soil, different indicator plants can be found in these. Examples of light pointers include:
84. Wormwood (Artemisia absinthium)
85. Common Thrift (Armeria maritima)
86. Yellow Rockrose (Helianthemum nummularium)
Examples of shadow pointers, on the other hand, are:
87. Wood sorrel (Oxalis acetosella)
88. Dog's mercury (Mercurialis perennis)
89. Golden nettle (Lamium galeobdolon)
Oxalis acetosella
With these species in particular, the dependency on the corresponding amount of light is clearly recognizable.
metallophytes
Finally, the metallophytes. These indicator plants are species that can store different types of heavy metals. They are usually better known by the following terms:
- ore plants
- metal indicator plants
- heavy metal plants
- Calamine plants (with high zinc tolerance)
If the soil is enriched with heavy metals, certain plants can point to them. Individual species store other heavy metals, which usually explains very well what you are dealing with:
90. Italian ryegrass (Lolium multiflorum): Lead
91. Cardaminopsis halleri: lead, nickel, zinc, cadmium
92. Calamine violets (Viola calaminaria and Viola guestphalica): Zinc
93. Reed canary grass (Phalaris arundinacea): germanium
94. Catchfly (Silene vulgaris): unspecified heavy metals
Viola guestphalica. Source: bdk, Viola guestphalica 01, crop from Plantopedia, CC BY-SA 3.0
These examples show you exactly when the soil is unsuitable for other plants. In particular, a large number of calamine plants is very evident. Larger accumulations are referred to as heavy metal turf.
Salty soil
The garden orache (Atriplex hortensis) belongs to the C3 plants and is one of the rare indicator plants for too high a salinity. While other plants die, the Spanish lettuce can easily thrive in saline soil. Numerous halophytes, the salt plants, also belong in this category. Others are:
95. Salt marsh grass (Spartina anglica)
96. Samphire (Salicornia)
97. Sea Lavender (Limonium)
98. Mugwort (Artemisia maritima)
99. Sea aster (Tripolium pannonicum)
100. Purslane-cocktail (Halimione portulacoides)
Many of the species are native to the North Sea and can be found in the salt marshes there, but can also spread to favorable locations.