Botany
Erect, branched, smooth undershrub, 0.8 to 1.5 meters high. Leaves are opposite, lanceolate, 7-14 cm long, 1-2.5 cm wide, pointed at the ends, green or variegated with short petioles. Flowers are small, in 4- to 12-cm long spikes, termimal or in axils of leaves. Corolla is smooth, 1.5 cm long, white with purple spots.

Distribution
Found along streams at low and medium altitudes, in secondary and primary forests.

Properties
Leaves contain a bitter alkaloid (justiciine) rich in potassium salts.
Considered anodye, antiperiodic, antispasmodic, carminative, diaphoretic, diuretic, emetic, febrifuge and laxative.
Phytochem screening showed the presence of alkaloids, flavonoids, saturated steroidal saponins or triterpinoidal saponins and amino acids.

Distribution
Found in all the islands, along streams.
Commonly planted around the house.

Parts used and preparation
Leaves, roots.
.
Uses
Folkloric
Decoction of boiled leaves used for postpartum baths (see: Suob)
Tea of leaves, 50 gms to a liter of boiling water, 5 glasses daily for fevers, cough, asthma, dysuria.
Fresh juice of leaves for children's cough and colic.
Mix 2 ounces of fresh juice from leaves with 1 ounce of coconut oil as a poultice for rheumatism.
Infusion of leaves for headaches.
Fresh juice of leaves for ear aches.
Fresh juice of leaves, mixed with mustard, is used as an emetic; also for asthma.
Tea of bitter tasting root for diarrhea, dysuria fevers: 50 gms to a pint of boiling water, 4 glasses daily.
Warmed salted leaves and tender stalks, in a bag, over musculoskeletal aches.
Plant decoction or wine infusion (30 gm in 1 liter of water) used for intermittent fevers.
Root, boiled in milk, for rheumatism, dysuria, fever, carbuncles, and diarrhea.
Leaves rubbed with Crinum asiaticum and black pepper used externally for lumbago.
Decoction of leaves for as diaphoretic and febrifuge.
Leaves are scattered in-between clothes to protect from insects.
Oil prepared from leaves useful for eczema.
In Sri Lanka, used for its analgesic action.
Others
Repellant: Dried leaves repel insects from clothing.

Studies
• Antinociceptive / Antioxidant: Study of JG aqueous leaf extract showed moderate and significant antinociceptive action, dose-dependent and of moderate duration. In addition, it also showed strong antioxidant activity.
• Immunosuppressive: Study of four medicinal plants that included J gendarussa showed inhibition of lymphocyte proliferation and suggests the extracts should be further investigated for their immunosuppressive components.
• Larvicidal / Mosquitocidal: Study of 11 commonly available medicinal plants, including J gendarussa, was evaluated for it larvicidal and mosquitocidal activities against Anopheles stephensi. All the extracts were found effective and the results suggest that these extracts are easy to prepare, inexpensive and safe for mosquito control.
• In Vitro HIV-1 Reverse Transcriptase Inhibition: Study of 20 Thai medicinal plants, J gendarussa was one of the extracts that showed reverse transciptase inhibition.
• Anti-Arthritic: Study of ethanolic extract of J gendarussa showed significant anti-arthritic activity statistically similar to aspirin.
• Anti-Angiogenic: Study showed both aqueous and ethanolic extracts of leaves of J gendarussa dose-dependently inhibits angiogenesis and provides scientific basis for its traditional use in the treatment of arthritis.
• Antioxidant / Hepatoprotective: Study showed the leaf extract of Justicia gendarussa has moderate hepatoprotective effect which may be due to its antioxidant and free radical scavenging potential.

Availability
Wild-crafted.