April 2017: At the end of an unusually warm March we already reached the blooming period of the common wood sorrel [Oxalis acetosella] (Sauerklee)! In early spring new light green leaves appear, followed by the first wispy flowers. We know more than 800 species of oxalis, but most of them are found in tropical and subtropical regions. Our wood sorrel is a record low-light plant: it can exist with 1/160 of normal daylight! To avoid excessive sunlight it can fold down its leaves. It disseminates its seeds explosively with more than 10 times the barometric pressure. It contains oxalic acid and potassium oxalate and is therefore slightly poisonous.
