common hop

(Humulus lupulus var. lupuloides)

Conservation Status

 

No image available

 
  IUCN Red List

not listed

     
  NatureServe

N4? - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FACU - Facultative upland

     
  Midwest

FACU - Facultative upland

     
  Northcentral & Northeast

FACU - Facultative upland

     
           
 
Description
 
 

Common hop (var. lupuloides) is a perennial vine that rises from a stout rhizome. It dies back to the ground each year.

The stem is stout, non-woody, light green, and branched. It is solid at maturity and usually finely ridged or angled. It is rough and prickly to the touch, and is sparsely to moderately covered with stiff, 2-branched hairs on the ridges. Each hair has two rigid branches that spread in opposite directions. These hairs facilitate climbing by anchoring the vine to adjacent plants or structures. The stem is hairiest at the nodes, and is hairless or minutely hairy between the branched hairs. It climbs by turning clockwise at the tip (twining). Charles Darwin observed that it made a complete revolution every 128 minutes during daytime in hot weather.

Leaves are opposite, broadly egg-shaped in outline, and heart-shaped at the base. They are on to 3 long leaf stalks (petioles). The petioles are usually shorter than the leaf blades. They are sometimes twining and, like the stem, are covered with stiff, 2-branched hairs. At the base of each leaf is a pair of lance-shaped, leaf-like appendages (stipules). The stipules are sometimes fused, appearing as a single stipule. Leaf blades are 1¼ to 6 long, and ¾ to 5 wide. They are mostly palmately divided into usually 3, rarely 5, lobes. The lobes taper to a point at the tip and are somewhat narrowed at the base. Leaves that are 4 long or longer usually have fewer than 5 lobes. Smaller leaves are sometimes unlobed. Leaves 2 long or shorter often have no more than 3 easily visible secondary veins branching off of the midrib, not counting branches near the base. The upper surface of the leaf blade is rough to the touch and is sparsely covered with stiff, prickly hairs. The lower surface is not rough to the touch. It is sparsely to moderately covered with short, fine, soft, white hairs along the veins and hairless but with yellow glands between the veins. The margins are toothed with sharp, forward pointing teeth.

Male and female flowers are borne on separate plants. The male inflorescence is loose, branched cluster (panicle) of 20 to 100 or more flowers at the end of the stem and drooping from leaf axils. The panicles are 1¼ to 6 long, and ¾ to 1¼ wide. The female inflorescence is a pair of dense, cone-shaped, to ¾ long spikes (aments) drooping from leaf axils. The ament consists of overlapping, dull green bracts.

Male flowers are star shaped, 1 32 to long, and about ¼ wide. There are 5 yellowish- or whitish-green sepals, no petals, and 5 stamens with glandular anthers. Female flowers consist of an ovary with a long, slender stigma. They are paired between overlapping bracts of the ament.

The ament elongates when in fruit, becoming to 2 long. The bracts are to ¾ long, egg-shaped, and hairless along the margins. The fruit is a yellowish, broadly egg-shaped to nearly spherical achene enclosed in a persistent, enlarged calyx and covered by a papery bract. It is covered with yellowish to orangish stalked glands that secrete a bitter substance, lupulin, used to flavor beers.

 
     
 

Height

 
 

Climbing: 3 to 20 long

 
     
 

Flower Color

 
 

Yellowish or whitish

 
     
 

Similar Species

 
 

Common hop (Humulus lupulus var. pubescens) lower leaf surface is conspicuously hairy. It is densely hairy along the veins and is also hairy between the veins.

Japanese hop (Humulus japonicus) is an annual. The petiole is as long or longer than the leaf blade. The leaf blade has 5 to 9 lobes. The leaf underside is rough to the touch with stiff, prickly hairs along the veins. The margins on the ament bracts are densely hairy. The bracts, anthers, and achenes are not glandular.

 
     
 
Habitat
 
 

Moist. Thickets, woodland borders, riverbanks, wooded bluff slopes, fencerows, railroads, disturbed areas. Partial sun.

 
     
 
Biology
 
 

Flowering

 
 

July to August

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

4, 7, 28.

 
  1/8/2014      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

 

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (dicots)  
  Subclass Rosidae  
  Superorder Rosanae  
 

Order

Rosales (roses, elms, figs, and allies)  
 

Family

Cannabaceae (hemp, hop, and hackberry)  
 

Genus

Humulus (hops)  
  Species Humulus lupulus (common hop)  
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Humulus americanus

Humulus lupulus ssp. americanus

 
       
 

Common Names

 
 

Arizona hops

common hop

 
       

 

 

 

 

 

 

 

 

Glossary

Achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 

Ament

A cylinder-shaped, spike-like inflorescence bearing unisexual flowers that have no petals.

 

Axil

The upper angle where a branch, stem, leaf stalk, or vein diverges.

 

Bract

Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.

 

Calyx

The group of outer floral leaves (sepals) below the petals, occasionally forming a tube.

 

Palmate

Similar to a hand. Having more than three lobes or leaflets that radiate from a single point at the base of the leaf.

 

Panicle

A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.

 

Petiole

The stalk of a leaf blade or compound leaf that attaches the leaf blade to the stem.

 

Rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

Sepal

An outer floral leaf, usually green but sometimes colored, at the base of a flower.

 

Stipule

A small, leaf-like, scale-like, glandular, or rarely spiny appendage found at the base of a leaf stalk, usually occurring in pairs and usually dropping soon.

 

Twining

Growing in a spiral usually around a stem of another plant that serves as support.

 
 
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