Common hop (var. lupuloides) is a vigorous perennial vine that grows from a stout rhizome and dies back to the ground each year. It grows quickly to its full length by June, then stops growing vertically and begins producing side arms and flowers. The rough, prickly stem has stiff hairs that anchor the vine to adjacent structures. It climbs by twining, or turning clockwise at the tip. Charles Darwin observed that it made a complete revolution every 128 minutes during daytime in hot weather.
Pollination is by wind, rather than insects.
Although parts of the plant are poisonous, the fruits are covered with yellowish- to orangish-stalked glands that secrete a bitter substance, lupulin, used to flavor beers.
Native habitats include thickets, woodland borders, riverbanks, wooded bluff slopes, fencerows, railroads, and disturbed areas.
Plant Characteristics:
Grows 15-25' long.
Grows in full or part sun. Produces more flowers in full sun.
Prefers average to moist, well-drained, fertile soils and tolerates sandy/loamy soils.
Flowers for two weeks July-August. Male plants produce drooping panicles up to 12" long and 6" wide. Each staminate flower has 5 sepals, 5 stamens, and no petals. The abundant, non-sticky pollen is easily dispersed into the air. Female plants produce cone-shaped spikes of pistillate flowers from the axils of the leaves. A spike of pistillate flowers is up to 3" long and 2" wide and consists of an ovary with a sticky stigma that is long and slender. The male flowers quickly turn brown and wither away, while the fruits (or 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. The male flowers quickly turn brown and wither. Fruits of the female flowers persist longer and gradually turn brown, resulting in a capsule with a single seed that is resinous and aromatic.
Opposite leaves are medium to yellowish green and up to 6" long and 4" wide. Smaller leaves are usually oval-cordate in shape, but larger leaves are palmate with 3 lobes (rarely with 5), a rough texture, and coarsely serrated margins. The stems and long, stout petioles are light green or tan and smooth to bristly.
Reproductive System: Male and female parts are on separate plants (dioecious). Reproduces by re-seeding itself. Only the females produce the cone-shaped "hops" used in brewing. The male plant serves as a pollinator and is not needed for the female plants to produce hop cones for brewing; the male plant IS needed for propagation.
Wildlife Value:
Host plant for larvae of hop vine borer and hop looper moths and of red admiral, question mark, comma, and gray hairstreak butterflies. The caterpillar of the latter species feed on the fruits and developing seeds. The abundant pollen of the staminate flowers attracts flower flies and small bees.
Caution: Leaves, flowers, and pollen are poisonous due to volative oils and bitter acids. Skin irritation upon contact.
Resources:
Cornell Cooperative Extension: https://ccemadison.org/agriculture/hops-program/growing-hops-at-home#:~:text=The%20hop%20plant%20produces%20best%20under%20specific,frost%20free%20days%20are%20needed%20for%20flowering.
Illinois Wildflowers: https://www.illinoiswildflowers.info/savanna/plants/am_hops.htm
Lady Bird Johnson Wildflower Center: https://www.wildflower.org/plants/result.php?id_plant=HULUL
Full profile soon!