Hippophae rhamnoides, also known as sea buckthorn, sandthorn, sallowthorn or seaberry, is a species of flowering plant in the family Elaeagnaceae, native to cold-temperate regions of Eurasia. It is a spiny deciduous shrub. The plant is used in the food and cosmetics industries, in traditional medicine, as animal fodder, in horticulture, and for ecological purposes.

Hippophae rhamnoides is a hardy, deciduous shrub that can grow between 2 and 4 m high (between 7 and 13 ft). It has a rough, brown or black bark and a thick, grayish-green crown. The leaves are alternate, narrow and lanceolate, with silvery-green upper faces. It is dioecious, meaning that the male and female flowers grow on different shrubs. The sex of seedlings can only be determined at the first flowering, which mostly occurs after three years. The male inflorescence is built up of four to six apetalous flowers, while the female inflorescence normally consists of only one apetalous flower and contains one ovary and one ovule. Fertilization occurs solely via wind pollination, so male plants need to be close to female plants to allow for fertilization and fruit production.

The oval or lightly roundish fruits grow in compact grapes varying from pale yellow to dark orange. Individual fruits weigh between 270 and 480 mg.

The plants have a developed and extensive root system, and the roots live in symbiosis with nitrogen-fixing Frankia bacteria. The roots also transform insoluble organic and mineral matters from the soil into more soluble states. Vegetative reproduction of the plants occurs rapidly via root suckers.

Sea buckthorn fruit contains sugars, sugar alcohols, fruit acids, vitamins, polyphenols, carotenoids, fiber, amino acids, minerals, and plant sterols. Species belonging to genus Hippophae accumulate oil both in the pulp and in seed of the fruit. Oil content in the pulp is 1.5–3.0%, while in seeds, oil is 11% of the fresh weight.

Major sugars in sea buckthorn fruits are fructose and glucose, with total sugar content of 2.7–5.3 g/100 ml of juice. Typical sourness of the fruits is due to high content of malic acid (0.8–3.2 g/100 ml of juice) while astringency is related to quinic acid (1.2–2.1 g/100 ml of juice). Major sugar alcohol in fruit is L-quebrachitol (0.15–0.24 g/100 ml of juice).

The fruit is rich in phytosterols (340–520 mg/kg), β-sitosterol being the major sterol compound as it constitutes 57–83% of total sterols.

Flavonols were found to be the predominating class of phenolic compounds, while phenolic acids and flavan-3-ols (catechins) represent minor components.