Gou Teng

Uncaria rhynchophylla is native to East and Southeast Asia, with its primary distribution centered in southern and central China.

• Native range includes provinces such as Hunan, Hubei, Guangdong, Guangxi, Guizhou, Yunnan, Fujian, Jiangxi, and Sichuan
• Also found in parts of Japan, Vietnam, and other Southeast Asian countries
• The genus Uncaria comprises approximately 34 species distributed across tropical and subtropical regions worldwide, with the greatest diversity in Southeast Asia and tropical Africa
• In traditional Chinese medicine, the highest-quality Gou Teng has historically been sourced from the provinces of Hunan and Hubei
• The plant has been cultivated in China to meet growing medicinal demand, though wild-harvested specimens are traditionally considered superior in quality

Uncaria rhynchophylla is a large, perennial, woody liana (climbing vine) that can reach considerable lengths in its natural habitat.

Stem & Hooks:
• Stems are cylindrical, brown to dark brown, with prominent longitudinal ridges or furrows
• The most distinctive feature is the presence of paired, hook-shaped thorns (modified branches) measuring approximately 1–2 cm long
• Hooks are curved, hard, and sharp — resembling fish hooks or cat claws — and serve as climbing organs
• Young stems are often pubescent (finely hairy), becoming smoother with age
• Internodes typically measure 5–12 cm in length

Leaves:
• Arranged in opposite pairs along the stem
• Leaf blades are elliptic to oblong-elliptic, approximately 6–12 cm long and 3–6 cm wide
• Leaf tips are acuminate (tapering to a point), bases are cuneate to rounded
• Upper surface is dark green and glossy; lower surface is paler, sometimes pubescent along veins
• Petioles are short, approximately 5–10 mm long
• Stipules are interpetiolar, ovate, and deciduous

Flowers:
• Small, yellowish-white, arranged in dense, globose, axillary or terminal heads (capitula) approximately 1–2 cm in diameter
• Each flower head contains numerous individual flowers
• Corolla is tubular with five lobes, approximately 5–7 mm long
• Flowers are fragrant, attracting insect pollinators
• Blooming period typically occurs in late spring to early summer

Fruit:
• A dry, capsular fruit approximately 7–10 mm long
• Dehisces (splits open) at maturity to release numerous small, winged seeds
• Seeds are tiny (~1 mm) with membranous wings aiding wind dispersal

Roots:
• Woody, extensive root system that anchors the climbing vine
• Roots can penetrate deeply into soil in forest environments

Uncaria rhynchophylla thrives in warm, humid subtropical and tropical forest environments.

• Typically found in montane forests, forest margins, thickets, and along stream banks at elevations of 200–1,500 meters
• Prefers well-drained, humus-rich soils in partially shaded environments
• Often climbs on trees and shrubs in mixed broadleaf forests, using its hooked thorns to ascend toward canopy light
• Requires a warm, humid climate with annual rainfall of approximately 1,000–2,000 mm
• Sensitive to frost; cannot tolerate prolonged freezing temperatures
• Commonly associated with other subtropical forest species in its native range
• Pollination is entomophilous (insect-pollinated), with small flies and bees visiting the fragrant flower heads
• Seed dispersal is anemochorous (wind-dispersed) via the small, winged seeds

Cultivation of Uncaria rhynchophylla is primarily undertaken for medicinal purposes and requires conditions mimicking its natural subtropical forest habitat.

Light:
• Prefers partial shade to dappled sunlight, similar to its natural understory habitat
• Avoid prolonged direct intense sunlight, which can scorch leaves
• Filtered light beneath tree canopies or shade cloth (50–70% shade) is ideal

Soil:
• Requires well-drained, humus-rich, slightly acidic to neutral soil (pH 5.5–7.0)
• A mix of loamy soil with organic compost and perlite or coarse sand works well
• Soil must retain moisture without becoming waterlogged

Watering:
• Keep soil consistently moist during the growing season
• Reduce watering in winter during dormancy
• Good drainage is essential to prevent root rot

Temperature:
• Optimal growth temperature: 20–30°C
• Cannot tolerate frost; minimum temperature should remain above 5°C
• In temperate regions, must be grown in greenhouses or as an indoor plant during cold months

Support:
• As a climbing liana, it requires a trellis, arbor, or host tree for support
• The hooked thorns will naturally grip onto available structures

Propagation:
• Primarily propagated by stem cuttings (semi-hardwood cuttings taken in summer)
• Can also be grown from seed, though germination rates may be variable
• Layering is another effective propagation method

Harvesting:
• The hooked stem segments (ramulus cum uncis) are harvested in spring and autumn
• Traditionally, stems with well-developed hooks are selected
• Dried in the sun or at low temperature for medicinal use

Gou Teng is one of the most valued herbs in traditional Chinese medicine (TCM), with a documented history of use spanning over a millennium.

Traditional Chinese Medicine:
• The medicinal part is the dried stem with hooked thorns (Ramulus Uncisiae Cum Uncis)
• First recorded in the Mingyi Bielu (名医别录, "Supplementary Records of Famous Physicians") during the Han Dynasty period
• Classified as having a sweet (甘) taste and slightly cold (微寒) nature
• Enters the Heart (心) and Liver (肝) meridians
• Primary traditional functions: clearing heat and calming the liver (清热平肝), extinguishing wind and stopping convulsions (息风止痉)
• Traditionally prescribed for headaches, dizziness, convulsions, epilepsy, hypertension, and febrile diseases in children

Modern Pharmacological Research:
• Contains bioactive indole alkaloids, most notably rhynchophylline (钩藤碱) and isorhynchophylline (异钩藤碱)
• These alkaloids have demonstrated antihypertensive effects through calcium channel blocking activity
• Studies have shown neuroprotective properties, with potential applications in neurodegenerative diseases such as Alzheimer's and Parkinson's disease
• Rhynchophylline has been investigated for its anti-inflammatory, antioxidant, and antiplatelet aggregation effects
• Research suggests potential benefits for cardiovascular health, including vasodilation and reduction of blood pressure
• Some studies indicate anticonvulsant properties, supporting its traditional use for treating convulsions

Preparation & Dosage:
• Typically prepared as a decoction (herbal tea/boil) in TCM formulations
• Standard dosage in decoction: 3–12 grams
• Should be added later in the decoction process (后下) to preserve volatile active compounds
• Also available in powdered form, tinctures, and as a component of patent medicines

Culinary:
• Occasionally used in herbal soups and teas in southern China as a health-promoting ingredient
• Not commonly used as a food plant