Humulus lupulus

Humulus lupulus L.

by Matt Rinker, Native Plants Class 2002
Common names: Common hops, Hops, European hops.
Family: Cannibaceae
Etymology:
Synonymy: Humulus americanus (L.) Nutt.

Identification
Growth form: Long, twining vine that climbs over rocks and up into trees (1).
Roots: An extensive root system that penetrates the soil to depths of 5 m or more (2).
Stem: Stems are rough, main stem is stripped like a candy cane (1). Twining stems that always wind in a clockwise direction (2).
Leaves: Palmately lobed and veined, 3 to 7 lobes per leaf with leaf margins serrate. Dark green above, lighter with prickly veins beneath, up to 10 inches long, 7 inches wide (1).
Inflorescence/flowers: Cream colored, regular, tiny, inconspicuous, superior ovary, 1 to 2 celled, to 1/8 inch wide, in loose clusters in leaf axils; followed by drooping cluster of overlapping bracts, up to 1 ¼ inches long, 1inch wide. Male inflorescence short lived (1).
Fruit: Fleshy or surrounded by bracts (1).
Similar species: The Japanese hop (H. japonicus) is a quick-growing annual species used as a screening vine (2).

Ecology
Life history: Hops is a long-lived perennial
Native/Introduced: Native
Photosynthetic pathway:
Phenology: In Arizona blooms from July-August. New vines are produced each season and die following maturity (2).
Distribution: Native to temperate North America, Eurasia, and South America. (2) Coniferous forest, rocky slopes, and stream banks, 5,500-9,500 feet (1).

Uses
Human: The hops used in the brewery industry are the dried female flower clusters (cones) of the common hop (H. lupulus). The brewing value of the cones is based on their content of bitter (soft) resins, essential oils, and perhaps tannins. These constituents, which are extracted from hops by boiling in wort (an aqueous infusion of malt), impart the desired mellow bitterness and delicate hop aroma to brewed beverages and aid in their preservation (2). The female flowers of which are used to flavor beer and to clarify it by precipitating the protein materials that causes turbidity. The active principles of the hop also help prevent spoilage by retarding the growth of bacteria in the beer. Hops can cause contact dermatitis (3).

References
1. Epple, Anne O., Epple Lewis E. 1995. A Field Guide to the Plants of Arizona. The Globe Pequot Press

2. "Hop" Encyclopedia Britannica <http://search.eb.com/eb/article?eu=41904> [Accessed November 3, 2002].

3. "Urticales" Encyclopedia Britannica http://search.eb.com/eb/article?eu=120815>
[Accessed November 3, 2002].

4. Natural Resources Conservation Service. Plants Database [On-line]. Available: http://plants.usda.gov/index.html

Humulus lupulus L. by Matt Rinker, Native Plants Class 2002 Common names: Common hops, Hops, European hops. Family: Cannibaceae Etymology: Synonymy: Humulus americanus (L.) Nutt. Identification Growth form: Long, twining vine that climbs over rocks and up into trees (1). Roots: An extensive root system that penetrates the soil to depths of 5 m or more (2). Stem: Stems are rough, main stem is stripped like a candy cane (1). Twining stems that always wind in a clockwise direction (2). Leaves: Palmately lobed and veined, 3 to 7 lobes per leaf with leaf margins serrate. Dark green above, lighter with prickly veins beneath, up to 10 inches long, 7 inches wide (1). Inflorescence/flowers: Cream colored, regular, tiny, inconspicuous, superior ovary, 1 to 2 celled, to 1/8 inch wide, in loose clusters in leaf axils; followed by drooping cluster of overlapping bracts, up to 1 ¼ inches long, 1inch wide. Male inflorescence short lived (1). Fruit: Fleshy or surrounded by bracts (1). Similar species: The Japanese hop (H. japonicus) is a quick-growing annual species used as a screening vine (2). Ecology Life history: Hops is a long-lived perennial Native/Introduced: Native Photosynthetic pathway: Phenology: In Arizona blooms from July-August. New vines are produced each season and die following maturity (2). Distribution: Native to temperate North America, Eurasia, and South America. (2) Coniferous forest, rocky slopes, and stream banks, 5,500-9,500 feet (1). Uses Human: The hops used in the brewery industry are the dried female flower clusters (cones) of the common hop (H. lupulus). The brewing value of the cones is based on their content of bitter (soft) resins, essential oils, and perhaps tannins. These constituents, which are extracted from hops by boiling in wort (an aqueous infusion of malt), impart the desired mellow bitterness and delicate hop aroma to brewed beverages and aid in their preservation (2). The female flowers of which are used to flavor beer and to clarify it by precipitating the protein materials that causes turbidity. The active principles of the hop also help prevent spoilage by retarding the growth of bacteria in the beer. Hops can cause contact dermatitis (3). References 1. Epple, Anne O., Epple Lewis E. 1995. A Field Guide to the Plants of Arizona. The Globe Pequot Press 2. "Hop" Encyclopedia Britannica <http://search.eb.com/eb/article?eu=41904> [Accessed November 3, 2002]. 3. "Urticales" Encyclopedia Britannica http://search.eb.com/eb/article?eu=120815> [Accessed November 3, 2002]. 4. Natural Resources Conservation Service. Plants Database [On-line]. Available: http://plants.usda.gov/index.html