common hop

(Humulus lupulus var. lupuloides)

               
Conservation Status

IUCN Red List

not listed

 

No image available

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

Nativity

Native

Occurrence

 

Habitat

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

Flowering

July to August

     
Flower Color

Yellowish or whitish

     
Height

Climbing: 3 to 20 long

     

Identification

This 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. 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 yellow glands that secrete a bitter substance, lupulin, used to flavor beers.

 
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 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 anthers are not glandular.


Distribution Distribution Map   Sources: 4, 7, 28.

Comments

 


Taxonomy

Family:

Cannabaceae (hemp)

 
Parent

common hop (Humulus lupulus)

 
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 or flower cluster.

 

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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