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Common Name: Hop

General Information

Humulus lupulus is a Perennial Climber up to 6.00 metres tall.
It is harvested from the wild for local use as a food, medicine and source of materials.

Known Hazards

Skin contact with the plant causes dermatitis in sensitive people[]. Hops dermatitis has long been recognized. Not only hands and face, but legs have suffered purpuric eruptions due to hop picking. Although only 1 in 3,000 workers is estimated to be treated, one in 30 are believed to suffer dermatitis[].
Dislodged hairs from the plant can irritate the eyes[].

Botanical References

,

Range

Much of Europe, including Britain, to W. Asia.

Habitat

Hedgerows, woodlands and sunny waste ground[].

Properties

Edibility Rating
Medicinal Rating
Habit	Perennial Climber
Height	6.00 m
Growth Rate	Medium
Pollinators	Wind
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

Easily grown in a good garden soil in sun or semi-shade[, ]. Prefers a deep rich loam[] and a warm sheltered position[]. Plants can succeed in dry shade if plenty of humus is incorporated into the soil, once established they are also somewhat drought tolerant[]. Hops are reported to tolerate an annual precipitation of between 31 and 137cm, an annual temperature in the range of 5.6 to 21.3°C and a pH of 4.5 to 8.2[].
Plants are very hardy tolerating temperatures down to about -20°c when dormant[]. The young shoots in spring, however, can be damaged by any more than a mild frost[].
A climbing plant, supporting itself by twining around the branches of other plants[].
Hops are frequently cultivated, both commercially and on a domestic scale, in temperate zones for their seed heads which have many medicinal qualities and are also used as a flavouring and preservative in beer. There are many named varieties[]. They grow best between the latitudes of 35 - 51°N and 34 - 43°S, with mean summer temperatures of 16 - 18°C[]. Generally, for beer making, the unfertilized seed heads are preferred and so most male plants are weeded out[].
Hops are fairly deep rooted, but with a network of shallow feeding roots. These horizontal feeding roots spread out at depth of 20 - 30 cm in the soil and give rise to fibrous roots in upper layers of soil[]. The vertical roots develop downwards to a depth of about 150 cm with a spread of 183 - 244 cm and have no fibrous roots[].
The bruised leaves are refreshingly aromatic whilst the flowers cast a pleasing scent[].
A food plant for many caterpillars[].
A dioecious species - both male and female forms must be grown if fruit and seed are required.

Edible Uses

Young leaves and young shoots - cooked[, , , , , , ]. The flavour is unique and, to many tastes, delicious[]. Young leaves can be eaten in salads[, ]. Use before the end of May[]. The leaves contain rutin[].
The fleshy rhizomes are sometimes eaten[].
A tea is made from the leaves and cones[]. It has a gentle calming effect[].
The dried flowering heads of female plants are used as a flavouring and preservative in beer[, ]. They are also medicinal[]. The flowering heads are sprinkled with bitter-tasting yellow translucent glands, which appear as a granular substance[]. This substance prevents gram-negative bacteria from growing in the beer or wort[]. Much of the hop's use as a flavouring and medicinal plant depends on the abundance of this powdery substance[]. The seeds contain gamma-linolenic acid, an essential fatty acid that is said to have many important functions in the human body and is rarely found in plant sources[].
The essential oil in the flowering heads is used as a flavouring in cereal beverages and mineral waters[]. Extracts from the plant, and the oil, are used as flavouring in non-alcoholic beverages, frozen dairy desserts, candy, baked goods and puddings, with the highest average maximum use level of 0.072% reported for an extract used in baked goods[].

Medicinal

Hops have a long and proven history of herbal use, where they are employed mainly for their soothing, sedative, tonic and calming effect on the body and the mind. Their strongly bitter flavour largely accounts for their ability to strengthen and stimulate the digestion, increasing gastric and other secretions[].
The female fruiting body is anodyne, antiseptic, antispasmodic, diuretic, febrifuge, hypnotic, nervine, sedative, stomachic and tonic[, , , , , , ]. Hops are widely used as a folk remedy to treat a wide range of complaints, including boils, bruises, calculus, cancer, cramps, cough, cystitis, debility, delirium, diarrhoea, dyspepsia, fever, fits, hysteria, inflammation, insomnia, jaundice, nerves, neuralgia, rheumatism, and worms[]. The hairs on the fruits contain lupulin, a sedative and hypnotic drug[, ]. When given to nursing mothers, lupulin increases the flow of milk - recent research has shown that it contains a related hormone that could account for this effect[]. The decoction from the flower is said to remedy swellings and hardness of the uterus[]. Hop flowers are much used as an infusion or can also be used to stuff pillows where the weight of the head will release the volatile oils[]. The fruit is also applied externally as a poultice to ulcers, boils, painful swellings etc[, ], it is said to remedy painful tumours[]. The female flowering heads are harvested in the autumn and can be used fresh or dried[].
Alcoholic extracts of hops in various dosage forms have been used clinically in treating numerous forms of leprosy, pulmonary tuberculosis, and acute bacterial dysentery, with varying degrees of success in China.
The female fruiting body contains humulone and lupulone, these are highly bacteriostatic against gram-positive and acid-fast bacteria[].
A cataplasm of the leaf is said to remedy cold tumours[].

Other Uses

A fine brown dye is obtained from the leaves and flower heads[, , ].
An essential oil from the female fruiting heads is used in perfumery[, ]. Average yields are 0.4 - 0.5%[].
Extracts of the plant are used in Europe in skin creams and lotions for their alleged skin-softening properties[].
A fibre is obtained from the stems[]. Similar to hemp (Cannabis sativa)[] but not as strong[], it is used to make a coarse kind of cloth[]. It is sometimes used for filler material in corrugated paper or board products, but is unsuited for corrugated paper because of low pulp yield and high chemical requirement, or for production of high-grade pulp for speciality paper[]. The fibre is very durable but it is difficult to separate, the stems need to be soaked beforehand for a whole winter[]. A paper can also be made from the fibre, the stems are harvested in the autumn, the leaves removed and the stems steamed until the fibres can be removed. The fibre is cooked for 2 hours with lye and then hand pounded with mallets or ball milled for 2½ hours. The paper is brown in colour[].

Propagation

Seed - sow spring in a cold frame[]. Germination is fairly quick. Prick out the seedlings into individual pots as soon as they are large enough to handle and plant out in the summer or following spring.
Division in spring as new growth begins[]. Very easy, you can plant the divisions straight out into their permanent positions if required[].
Basal cuttings in early spring. Harvest the shoots when they are about 10 - 15cm long with plenty of underground stem. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.