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Knotgrass (Polygonum aviculare)

Botanical Information

  • Family: Polygonaceae
  • Common Names: Knotgrass, Common Knotweed, Birdweed, Doorweed
  • Parts Used: Aerial parts (leaves, stems, flowers)

Description

Polygonum aviculare, commonly known as Knotgrass, is a hardy, low-growing herbaceous plant found in temperate regions worldwide. Traditionally used in European, Chinese, and Native American herbal medicine, it is valued for its diuretic, anti-inflammatory, and astringent properties. Knotgrass has been used to support urinary tract health, digestive function, and wound healing.

Historical and Traditional Uses

  • Used in European folk medicine for kidney and urinary tract health.
  • Traditionally applied to wounds and ulcers to promote healing.
  • Employed as a digestive tonic to relieve diarrhea and intestinal inflammation.
  • Used in Traditional Chinese Medicine (TCM) for clearing heat and detoxifying the body.

Constituents

  • Flavonoids (avicularin, quercetin)
  • Tannins
  • Silica
  • Phenolic acids
  • Mucilage

Actions

  • Diuretic
  • Astringent
  • Anti-inflammatory
  • Antimicrobial
  • Vulnerary (Wound healing)

Medicinal Uses

1. Urinary Tract Health:
Knotgrass is a mild diuretic, traditionally used to support kidney function and relieve urinary tract infections.

2. Digestive Support:
Astringent properties help alleviate diarrhea and soothe intestinal inflammation.

3. Wound Healing:
Used externally to promote tissue repair and reduce inflammation in wounds, cuts, and ulcers.

4. Respiratory Support:
Traditionally used to relieve coughs, sore throats, and lung congestion.

5. Joint and Bone Health:
Rich in silica, knotgrass may support connective tissue and bone strength.

Preparation and Dosage

Infusion (Tea from Aerial Parts):

  • 1-2 tsp of dried herb per cup of hot water. Steep for 10-15 minutes. Drink up to twice daily.

Tincture:

  • 2-5 ml taken up to twice daily.

Poultice (Topical Use):

  • Crushed fresh plant applied to wounds or irritated skin.

Precautions and Contraindications

  • Pregnancy and Lactation: Consult a healthcare provider before use.
  • Kidney Conditions: Diuretic properties may not be suitable for individuals with kidney disorders.
  • Excessive Use: High doses may cause digestive discomfort due to tannin content.

Energetics (Traditional Medicine Perspectives)

  • Traditional Western Herbalism: Cooling and drying; supports urinary and digestive health.
  • Traditional Chinese Medicine (TCM): Clears heat, resolves dampness, and detoxifies.
  • Ayurveda: Balances Kapha and Pitta, but may aggravate Vata in excess.

Combinations

  • For Urinary Health: Combine with nettle and dandelion.
  • For Digestive Support: Combine with chamomile and peppermint.
  • For Wound Healing: Combine with calendula and plantain.

Harvesting and Storage

  • Harvesting: Aerial parts are collected in summer when in full bloom.
  • Drying: Air dry in a well-ventilated area away from direct sunlight.
  • Storage: Store dried herb in airtight containers away from moisture and light.

Modern Research

Studies confirm Polygonum aviculare’s diuretic, antimicrobial, and wound-healing properties, reinforcing its traditional applications.

Knotgrass remains a valuable herb in both traditional and modern herbal medicine, particularly for urinary health, digestive support, and wound healing.