born at the base of the leaves similar to nettles. The flower spikes (about long) appear between February and May. The catkin-like male flowers have a yellow color (due to yellow stamens) and female flowers have 3 tepals (petals and sepals are combined or indistinguishable). Taxonomy The genus Mercurialis belongs to the family Euphorbiaceae and to the subfamily Crotonoideae. It is included in the tribe Acalyphae, which is characterized by clusters of flowers It is also characterized by the lack of any laticiferous tissue, in the place of which tanniniferous cells (or tissue) are sometimes found. According to Pax (1914), there are three other genera related to Mercurialis; Seidelia, Leidesia and Dysopsis. The differences between these are based on the characteristics of the calyx and stamens. The genus Mercurialis itself consists of nine species and the main taxonomic characteristics used in distinguishing them are the clusters of floration, the annual or perennial habit, and the glabrous or hairy condition of the vegetative organs, but chiefly the ovary and the capsule, the woody or herbaceous nature of the plant, and lastly the character of the lamina. Plant community Dog's mercury is one of the characteristic plants of several woodland types, in particular: W8 Fraxinus excelsior - Acer campestre - Mercurialis perennis woodland W9 Fraxinus excelsior - Sorbus aucuparia - Mercurialis perennis woodland W12 Fagus sylvatica - Mercurialis perennis woodland Variations in morphology M. perennis has variation in its morphological characters. This is noticeable in the outline, shape, and hairiness of its leaves, in the size of the lower leaves, in the number of stamens, and in the size of the seeds and fruits. M. perennis possesses three distinct varieties are: M. perennis L. var. genuina Miiller-Aarg M. perennis L. var. Salisburyana Mukerji (Mukerji, 1927). M. perennis L. var. leiocarpa Mukerji (syn. M. leiocarpa Sieb. et Zucc.) Note:- M. perennis L. var. Salisburyana Mukerji (Mukerji, 1927) was discovered in March 1926 at Staplehurst (Kent). It differs from M. perennis L. var. genuina Miiller-Aarg in the following respects: serrated leaf margin shorter petiole darker green color more hispid character shorter and upwardly directed stigmas Habitat variation Besides those three variations of M. perennis there are six habitat forms in nature: f. silvatica (Hoppe s. str.). Leaves elongated, elliptic-lanceolate, pointed. Mid-nerve and veins of the leaves usually are thicker. f. ovatifolia (Hausskn.). Leaves ovate to ovate-lanceolate, the upper part of the stem above the