St. Mary’s wort (Polygonum persicaria)

The Grass of Santa María or Polygonum persicaria is a cultivated plant belonging to the family of Polygonaceae and which is composed of more than 200 species of herbaceous plants widely distributed on all continents.

This is known by various names such as turkey mucus, pejiguera grass, polygon and persicaria.


It belongs to the genus of plants called ruderal, which are those that proliferate in areas altered by natural phenomena such as avalanches and also by constructions and agricultural activities carried out by human hands.

These ruderal species usually remain for some time in the altered areas, but as long periods pass they lose ground in relation to the native species of the region, although if the alteration is continuous, they can establish and form long-lasting populations.

The polygons according to their classification can be creeping, climbing or upright, their leaves are also diverse, between linear or oval and their small flowers with the absence of petals appear in spikes of various colors, generally three and which are pink, yellow and white.

The usefulness of this species is to cover the cleared areas of our gardens with respect to the so-called climber, which serves to decorate our terraces and balconies.

Its physical characteristics are erect stems whose size ranges between 10 and 80 centimeters, very straight and descending, of limited thickness at the nodes, subsssile lanceolate leaves, few hairy on the underside or lower each and in the case of the glabrous ones, on their nerve. central or middle, sometimes a black spot can be distinguished that distinguishes and identifies it.

Its straight stem at times and in certain circumstances, can lean in such a way that it falls to the ground, this results in that from each node of the stem a new root is generated that holds the plant to the ground and over time, new stems grow back. vertical and straight.

Its flowering time covers a period of six months between May and October both inclusive and its fruits are called achene trine or dried fruit.

The physical and geographical factors in which this plant develops fully, are those altered soils, gutters, ditches, stream edges, etc.

They grow in full light and semi-shade with soils that retain moisture and rich in organic matter, and with medium heating temperatures. The adequate pH should be between 5.5.-8 and soils enriched with nitrogen, synonymous with multiple nutrients.

Regarding its biological type, it is a species whose seeds last in times that are not favorable to it, a quality for which it is called therophile, to which they belong.

Pests and diseases of Polygonum persicaria

These plants have the peculiarity of not suffering attacks from pests and diseases that usually affect other garden plants.

It is normal to find them in the regions that make up the Iberian peninsula between Mallorca and Menorca and in many other towns such as La Coruña, Almería, Asturias and Gijón.

It is also known as a perennial or deciduous plant and contains persicarin and tannins. It said the Polygonium is useful for the treatment of diarrhea by tannic acid which helps in this type of stomach ailments, and is frequently used in medicine.


Its fresh leaves are used quite effectively in the containment of hemorrhages, heals sores and external ulcers on the skin, as well as it is used as an astringent. However, they are considered of the aggressive genus or weeds, as they are commonly known.

The young leaves and shoots can be consumed in salads as they are nutritious and taste good.


As for its care and as we have already mentioned above, this species for its full development requires moderate exposure to the sun ; if it is in a not very hot climate it can thrive in full sun.

With reference to the risks, the care is varied depending on the species. It differs from that of the mountain species, whose irrigations must be continuous unlike those in warmer climates that require more moderate irrigation.

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