Rosin Weed, Curlycup gumweed

Grindelia squarrosa

Physical Characteristics

Grindelia squarrosa is a BIENNIAL/PERENNIAL growing to 1 m (3ft 3in). See above for USDA hardiness. It is hardy to UK zone 3. It is in flower from July to September. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Suitable for: light (sandy) and medium (loamy) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil and can tolerate drought.

Distribution

N. America - Minnesota to British Columbia, south to California and Texas.

Habitats

Cultivated Beds;

Edible Uses

Edible Parts: Edible Uses: Gum Tea The fresh or dried leaves can be used to make an aromatic, slightly bitter but pleasing tea[183]. A sticky resinous sap that covers the leaves can be used as a chewing gum substitute[183].

Medicinal Uses

Antispasmodic Eczema Expectorant Homeopathy Poultice Sedative Rosin weed was used by the native North American Indians to treat bronchial problems and also skin afflictions such as reactions to poison ivy[254]. It is still used in modern herbalism where it is valued especially as a treatment for bronchial asthma and for states where phlegm in the airways impedes respiration[254]. In addition, it is believed to desensitize the nerve endings in the bronchial tree and slow the heart rate, thus leading to easier breathing[254]. The plant merits investigation as a treatment for asthma[222]. The herb is contraindicated for patients with kidney or heart complaints[254]. The dried leaves and flowering tops are antiasthmatic, anti-inflammatory, antispasmodic, expectorant and sedative[4, 46, 207, 212, 238, 254]. The principal use of this herb is in the treatment of bronchial catarrh, especially when there is an asthmatic tendency, it is also used to treat whooping cough and cystitis[4, 254]. The active principle is excreted from the kidneys, and this sometimes produces signs of renal irritation[4, 238]. Externally, the plant is used as a poultice to treat burns, poison ivy rash, dermatitis, eczema and skin eruptions[212, 213, 222, 238]. The plant is harvested when in full bloom and can be used fresh as a poultice or dried for infusions etc[254]. A fluid extract is prepared by placing the freshly gathered leaves and flowers in a small quantity of simmering water for about 15 minutes[213]. A homeopathic remedy is prepared from the leaves and flowering stems[4].

Known Hazards

The plant contains the carcinogen safrole[274].