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. 2n = 20, including 2 or more sex-determining chromosomes.
Alta., B.C., Man., N.B., N.S., Nfld. and Labr. (Nfld.), Ont., P.E.I., Que., Sask., Ariz., Ark., Calif., Colo., Conn., Del., Ill., Ind., Iowa, Kans., Ky., Maine, Mass., Md., Mich., Minn., Mo., Mont., N.C., N.Dak., N.H., N.J., N.Mex., N.Y., Nebr., Nev., Ohio, Okla., Pa., R.I., S.Dak., Tex., Utah, Va., Vt., W.Va., Wis., Wyo.
Varieties 5 (4 in the flora).
Humulus lupulus has often been transplanted from the wild to homesites as an ornamental. When such sites are abandoned, the plants often persist, and it may appear that they are present naturally. As well, suppliers of ornamental plants may sell hops collected from one site to buyers in a quite distant site. The hop varieties discussed here may therefore be found occasionally beyond the distribution ranges given in this treatment.
Native Americans used Humulus lupulus medicinally to induce sleep, for breast and womb problems, for inflamed kidneys, rheumatism, bladder problems, intestinal pain, fever, earaches, pneumonia, coughs, and nervousness, as a tonic and a stimulant, and as a witchcraft medicine (D. E. Moerman 1986).
The measurements mentioned in couplet 1 of the following key are taken in the middle abaxial portion of the central lobe on 4-6 cm leaf blades attached to flowering or fruiting twigs.
|1||Leaf blades usually with fewer than 20 hairs per cm on length of midrib, fewer than 25 glands per 10 sq. mm between veins; nodes relatively limited in pubescence, usually fewer than 15 hairs per 0.1 sq. mm at most pubescent portion (excluding angle of petiole with stem).||Humulus lupulus var. lupulus|
|1||Leaf blades usually with more than 20 hairs per cm on length of midrib, more than 25 glands per 10 sq. mm between veins; nodes relatively pubescent, usually more than 15 hairs per 0.1 sq. mm at most pubescent portion (excluding angle of petiole with stem).||> 2|
|2||Leaf blades 10 cm or more usually having at least 5 lobes; smaller blades (ca. 5 cm) usually with more than 3 easily visible veins branching off midrib (excluding proximal branches).||Humulus lupulus var. neomexicanus|
|2||Leaf blades 10 cm or more usually having fewer than 5 lobes; smaller blades (ca. 5 cm) often with no more than 3 easily visible veins branching off midrib (excluding proximal branches).||> 3|
|3||Leaf blades conspicuously pubescent abaxially, more than 100 hairs per cm on length of medial midrib, hairs present between veins.||Humulus lupulus var. pubescens|
|3||Leaf blades not conspicuously pubescent abaxially, usually fewer than 100 hairs per cm on length of medial midrib, hairs usually absent between veins.||Humulus lupulus var. lupuloides|