Materia Medica

Oats & Oatstraw (Avena sativa) — Wild Oats, Common Oat
A guide to Avena sativa covering oat grain, oatstraw, milky oats, beta-glucan, traditional nervous-system use, celiac disease and gluten contamination. Read more...
Oregano (Origanum vulgare) — Wild Marjoram, Pot Marjoram
A guide to Origanum vulgare covering oregano's culinary and traditional use, laboratory antimicrobial research, essential-oil irritation risk and safety. Read more...
Olive Leaf (Olea europaea) — Olive, Oleuropein
A research-grounded guide to olive leaf (Olea europaea), covering Mediterranean traditional use, oleuropein and other phenolics, human cardiometabolic research, newer meta-analysis findings, product differences and safety. Read more...
Oregon Grape (Berberis aquifolium) — Holly-Leaved Barberry, Mountain Grape
A research-grounded guide to Oregon grape (Berberis aquifolium / Mahonia aquifolium), covering taxonomy, berberine-rich root bark, traditional bitter-herb use, topical psoriasis trials, evidence limits, drug interactions and pregnancy safety. Read more...
Orris Root (Iris × germanica) — Iris Root, Florentine Iris
A research-grounded guide to orris root from Iris × germanica and Iris pallida, covering violet-like irone fragrance, perfumery and flavor tradition, herbal history, limited clinical evidence, species identification and irritation/allergy safety. Read more...
Osha (Ligusticum porteri) — Bear Root, Colorado Cough Root
A research-grounded guide to osha or bear root (Ligusticum porteri), covering Indigenous and Hispanic Southwestern traditions, respiratory-use history, limited modern clinical evidence, wild-harvest conservation, poisonous Apiaceae look-alikes and safety. Read more...
Oriental / Asian Water-Plantain — Ze Xie (Alisma plantago-aquatica subsp. orientale; syn. Alisma orientale): Traditional Use, Alisols, Diuretic Research, Processing & Safety
Oriental or Asian water-plantain (Alisma plantago-aquatica subsp. orientale; syn. Alisma orientale), known in Chinese medicine as Ze Xie / Alismatis Rhizoma, is an aquatic East Asian herb whose dried subterranean medicinal material has a long fluid-balance tradition. This guide covers current taxonomy, traditional processing, alisol triterpenoids, diuretic and metabolic research, limited human evidence, and dose- and preparation-dependent kidney and electrolyte safety. Read more...