Humulus (Hop) is a small genus comprising three species of flowering plants in the family Cannabaceae, native to temperate regions of Northern Hemisphere. Hops are the female flower clusters (commonly called seed cones or strobiles) of Humulus lupulus, use primarily as a flavoring and stability agent in beer, which they give a bitter, tangy flavor to the brew.
Humulus is a vigorous climbing herbaceous perennial, usually trained to grow up strings in a field called hop field, hop garden or hop yard. Hop bines have stout stems with stiff hairs to aid in climbing. The bines climb by wrapping clockwise around anything within reach. The plant sends up new shoots in early spring and dies back to cold-hardy rhizomes in autumn. Humulus leaves are opposite, with a leaf stalk of 7 -12 cm, and a heart-shaped, fan-lobed blade 12 - 25 cm long and broad. The leaves have coarsely toothed edges.
Hops are used extensively in brewing today for their many purported benefits, including balancing the sweetness of malt with bitterness, providing a variety of desirable flavors and aromas, and for their preservative qualities. Different varieties of hops are grown by farmers around the world, with different types for particular styles of beer.
Humulus plant is dioecious, with male and female flowers develop on separate plants. Female plants, which produce the hop flowers used in brewing beer are often propagated vegetatively and grown in the absence of male plants. This prevents pollination and the development of viable seeds which are undesirable for brewing beer. Male plants are culled if plants are grown from seeds.
Humulus lupulus (Common hop) is a dioecious, twining perennial plant native to the temperate regions of Northern Hemisphere. It has lobed, light-green leaves. The plant sends up new shoots in early spring and dies back to cold-hardy rhizome in autumn. Female plants bear the decorative green flowers called hops in autumn, hidden by aromatic bracts. Small yellow flowers are borne in clusters of 10 cm long on male plants. Although this species is decorative, it is not commonly grown in garden. Instead another cultivar H. lupulus 'Aureus' is preferred. It needs full sun for the leaves to display their best color. The twining bines can be trained over arches, fences, pergolas or nettings.
Humulus do well in sun or partial shade, in moisture-retentive but well-drained soil. Propagation is by seed in spring, softwood cuttings in spring, or greenwood cuttings in summer. Pests and diseases are hop aphids, red spider mite, downy mildew and powdery mildew.
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