Ellenberg - Reaction

Reaction refers to environmental acidity, which would ordinarily be measured by pH. Except for water plants, Ellenberg R values reflect preferences for soil acidity.

 

Ellenberg value

Explanation

1

Indicator of extreme acidity, never found on weakly acid or basic soils (Andromeda polifolia, Lycopodium clavatum, Rubus chamaemorus, Ulex minor)

2

Between 1 and 3 (Agrostis curtisii, Calluna vulgaris, Drosera rotundifolia, Polygala serpyllifolia)

3

Acidity indicator, mainly on acid soils, but exceptionally also on nearly neutral ones (Agrostis vinealis, Dactylorhiza maculata, Galium saxatile, Pteridium aquilinum)

4

Between 3 and 5 (Agrostis capillaris, Carex panicea, Juncus effusus, Teucrium scorodonia)

5

Indicator of moderately acid soils, only occasionally found on very acid or on neutral to basic soils (Cardamine pratensis, Cirsium palustre, Rubus idaeus, Ulex europaeus)

6

Between 5 and 7 (Ammophila arenaria, Carex sylvatica, Lolium perenne, Ranunculus ficaria)

7

Indicator of weakly acid to weakly basic conditions; never found on very acid soils (Agrimonia eupatoria, Atriplex prostrata, Nuphar lutea, Phleum pratense)

8

Between 7 and 9 (Artemisia vulgaris, Carduus nutans, Iris foetidissima, Viola hirsuta)

9

Indicator of basic reaction, always found on calcareous or other high-pH soils (Bunium bulbocastanum, Clinopodium calamintha, Dryopteris submontana, Primula farinosa)