Humulus lupulus

This native perennial vine is up to 30' long; it dies back to the ground each year. The stems are stout, light green, and rather prickly-bristly. The opposite leaves are up to 6" long and 4" across; smaller leaves are usually oval-cordate in shape, but larger leaves are palmate with 3 lobes (rarely with 5). These leaves have a rough texture, coarse serration along the margins, and long petioles that are also prickly-bristly. At the base of each leaf is a pair of lanceolate stipules. The hairiness or pubescence of the stems and foliage is variable, if it is present at all. Usually, there are small white hairs along the major veins on the underside of each leaf. American Hops is dioecious, with male and female plants. The male plants produce drooping panicles of staminate flowers. These panicles are up to 12" long and 6" across, and contain numerous small flowers that are yellowish or whitish green. Each staminate flower has 5 sepals, 5 stamens, and no petals. It has a star-like appearance and spans about ¼" across, hanging downward from a slender pedicel that is often slightly pubescent. The non-sticky pollen is produced in great abundance and is easily dispersed into the air. The female plants produce odd-looking cone-shaped spikes of pistillate flowers (aments) from the axils of the leaves. A spike of pistillate flowers is up to 3" long and 1½" across, and usually hangs downward from the slender flowering stalk. It consists of overlapping green bracts that are ovate, with a pair of pistillate flowers tucked between each adjacent pair of bracts. Each pistillate flower consists of little more than an ovary with a sticky stigma that is long and slender. Both the male and female flowers bloom during the late summer for about 2 weeks. The male flowers quickly turn brown and wither away, while the aments of the female flowers persist longer and gradually turn brown. Each pistillate flower produces a capsule with a single seed that is resinous and aromatic. This plant reproduces by reseeding itself.

American Hops has some resemblance to grapevines, but it is a coarser and more bristly plant that flowers late in the year, while the latter flowers during the spring. The female fruit of hops is used to flavor beer and prevent decay during fermentation from bacterial processes. It is possible that the wind-dispersed pollen may cause allergic reactions in some people. There are both European and American varieties of this species, and it is quite possible that they have interbred in the wild. Consequently, they are often hard to distinguish. There is a variety of American Hops that has unlobed leaves. A non-native species of hops that occurs in the wild, Humulus japonicus (Japanese Hops) is an annual vine that has leaves with more lobes (5-7) than American Hops. Furthermore, the lobes of its leaves are more narrow and pointed than those of American Hops.

American Hops is a common plant that occurs in most areas of central and northern Illinois; however, it less common or absent from many areas of southern Illinois (see Distribution Map). American Hops occurs in openings of both upland and floodplain forests, woodland borders, thickets, and slopes of bluffs. In more developed areas, it is found along fence rows, vacant lots, areas along railroads, and miscellaneous waste areas. This plant favors areas that are more or less disturbed, whether from human activities or natural causes. It often clambers over surrounding vegetation, including shrubs and small trees.

Humulus lupulus L.:
United States (North America)
China (Asia)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Distribution: North America, South Europe, Western Asia.

Clockwise twining climber with stout root stock. Stem 3-6 m. tall, scabrid or prickly. Leaves broadly ovate, more or less cordate at base, usually deeply 3-5 lobed, serrate, 6-12 cm in diameter, lobes acuminate, petiole shorter or equal to blade. Male panicle 7.5-10 cm. in diameter with c 5 mm across flowers. Female inflorescence 12-15 mm. in diameter with yellow flowers; bract 10 mm. long, ovate, acute, pale green ; styles purple. Etaerio of achenes 3-4 cm in diameter.

Plants perennial. Petiole usually shorter than leaf blade; leaf blade 3-5(-7)-lobed, sometimes simple, 4-11 × 4-8 cm, abaxially glabrous or with scattered soft pubescence but without rigid spinulose hairs on veins, adaxially with few or no cystolith hairs marginally when young, base cordate, margin coarsely serrate, apex acute. Female flowers 2 per bract at least in middle of inflorescence; bracts imbricated into a globose spike. Infructescences globose, 3-4 cm in diam.; bracts ovoid, 1.5-2 cm, dry, membranous, apex acute. Achenes flat, included in bracts. Fl. autumn.

Herbs , perennial, rhizomatous, 1-6(-7) m. Stems branched. Leaves: petioles usually shorter than blades. Leaf blade ± cordate, palmately 3-7-lobed, sometimes unlobed, 3-15 cm, margins dentate-serrate; surfaces abaxially with veins glabrous or with soft pubescence, without straight, erect hairs, glands yellow, adaxially margins of younger leaf blades with few or no cystolithic hairs. Inflorescences: staminate with flowers whitish to yellowish, anthers glandular; pistillate usually racemes, 10-20 mm, pedunculate; bracteole margins not ciliate-hairy. Infructescences pendulous, pale yellow, conelike, ovoid to oblong, (1-)2-3(-6) cm; bracteoles with yellow glands. Achenes yellowish, ovoid, compressed, glandular. 2 n = 20, including 2 or more sex-determining chromosomes.

American Hops is a common plant that occurs in most areas of central and northern Illinois; however, it less common or absent from many areas of southern Illinois (see Distribution Map). American Hops occurs in openings of both upland and floodplain forests, woodland borders, thickets, and slopes of bluffs. In more developed areas, it is found along fence rows, vacant lots, areas along railroads, and miscellaneous waste areas. This plant favors areas that are more or less disturbed, whether from human activities or natural causes. It often clambers over surrounding vegetation, including shrubs and small trees.

Gansu, N Sichuan, Xinjiang [N Africa, N and NE Asia, Europe, E North America].

Pollination is by wind, rather than insects. However, the abundant pollen of the staminate flowers attracts flower flies and small bees. The caterpillars of several butterflies feed on hops, including Vanessa atalanta (Red Admiral), Polygonia interrogationis (Question Mark), Polygonia comma (Comma), and Strymon melinus (Gray Hairstreak). The caterpillars of the latter feed on fruits and seeds. The caterpillars of moths that feed on hops include Eudryas grata (Beautiful Wood Nymph) and Hydraecia immanis (Hop Vine Borer Moth). Little information appears to be available for this plant's relationships to birds and mammals.

Foodplant / miner
solitary larva of Agromyza flaviceps mines leaf of Humulus lupulus
Other: sole host/prey

Foodplant / miner
larva of Agromyza igniceps mines leaf of Humulus lupulus
Other: sole host/prey

In Great Britain and/or Ireland:
Foodplant / pathogen
Armillaria mellea s.l. infects and damages Humulus lupulus

Foodplant / spot causer
epiphyllous, immersed, brownish pycnidium of Ascochyta coelomycetous anamorph of Ascochyta humuli causes spots on live leaf of Humulus lupulus

Foodplant / pathogen
Botrytis dematiaceous anamorph of Botrytis cinerea infects and damages live Humulus lupulus

Foodplant / saprobe
sessile apothecium of Clavidisculum humuli is saprobic on dead stem of Humulus lupulus

Foodplant / parasite
haustorium of Cuscuta europaea parasitises stem of Humulus lupulus
Other: major host/prey

Foodplant / saprobe
gregarious perithecium of Diaporthe sarmenticia is saprobic on dead stem of Humulus lupulus

Foodplant / false gall
clustered perithecium of Gibberella pulicaris causes swelling of dead stem of Humulus lupulus
Remarks: season: 1-4
Other: minor host/prey

Foodplant / saprobe
fruitbody of Lachnella alboviolascens is saprobic on dead stem (large) of Humulus lupulus

Foodplant / gall
Meloidogyne incognita causes gall of root of Humulus lupulus

Foodplant / internal feeder
larva of Mitoplinthus caliginosus feeds within rootstock of Humulus lupulus

Foodplant / spot causer
amphigenous colony of Mycocentrospora coelomycetous anamorph of Mycocentrospora cantuariensis causes spots on live leaf of Humulus lupulus

Foodplant / saprobe
short-stalked apothecium of Pezizella discreta is saprobic on dead stem of Humulus lupulus
Remarks: season: 10-11

Foodplant / parasite
Phacidiopycnis coelomycetous anamorph of Phacidiopycnis tuberivora parasitises live Humulus lupulus

Foodplant / sap sucker
Phorodon humuli sucks sap of live shoot of Humulus lupulus
Remarks: season: 5-

Foodplant / saprobe
Phycomyces is saprobic on spent hop (inflorescence) mulch of Humulus lupulus

Foodplant / spot causer
amphigenous, scattered, smoky-yellow pycnidium of Phyllosticta coelomycetous anamorph of Phyllosticta humuli causes spots on fading leaf of Humulus lupulus

Foodplant / pathogen
Phytophthora citricola infects and damages live root of Humulus lupulus

Foodplant / parasite
cleistothecium of Podosphaera macularis parasitises Humulus lupulus
Remarks: season: 8-9

Foodplant / parasite
sporangium of Pseudoperonospora humuli parasitises live cone of Humulus lupulus
Remarks: season: 8-9,5
Other: sole host/prey

Foodplant / saprobe
apothecium of Psilachnum tami is saprobic on dead stem of Humulus lupulus

Foodplant / open feeder
imago of Psylliodes attenuata grazes on leaf of Humulus lupulus

Foodplant / saprobe
embedded sclerotium of Sclerotinia sclerotiorum is saprobic on dead, decaying stem of Humulus lupulus

Foodplant / spot causer
epiphyllous, central but scattered pycnidium of Septoria coelomycetous anamorph of Septoria humuli causes spots on fading leaf of Humulus lupulus

Plant / resting place / within
female of Thrips albopilosus may be found in live flower of Humulus lupulus
Remarks: season: 7-9

Foodplant / pathogen
Verticillium albo-atrum infects and damages Humulus lupulus

Foodplant / pathogen
Verticillium dahliae infects and damages Humulus lupulus

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 18
Specimens with Barcodes: 25
Species With Barcodes: 1

Rounded Global Status Rank: G5 - Secure

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

The preference is partial or full sun, fertile soil, and moist to slightly dry conditions. This robust plant will also grow in poor soil that is rocky or gravelly. It can be quite aggressive and appears to have few problems with disease.