Humulus japonicus
Humulus
houblon japonais, Japanese hop, Japanese hop(s)
hop, houblon
usually branched, armed with rigid 2-branched, stalked hairs that facilitate climbing.
blade cordate, palmately 5-9-lobed, 5-12 cm, margins of lobes serrulate, apex acuminate;
surfaces abaxially with veins pubescent, with stiff hairs, glands yellow, sessile, discoid, adaxially margins of younger leaf blades with stiff cystolithic hairs.
blade mostly cordate, palmately lobed, sometimes unlobed;
surfaces abaxially resin-dotted and×or gland-dotted.
staminate inflorescences erect, 15-25 cm, flower anthers without glands; pistillate inflorescences spikes, conelike, ovoid;
bracteole ovate-orbiculate, 7-10 mm, pilose, margins densely ciliate-hairy.
staminate inflorescences axillary and terminal, cymose panicles, erect to pendent, (10-)20-100+-flowered, flowers small; pistillate axillary, spikes or racemes, flowers solitary or paired, short-pedicellate, subtended by bracts and bracteoles.
pendulous, green, conelike, ovoid to oblong, (1-)1.5-3(-4) cm;
bracteoles without yellow glands.
yellow-brown, ovoid-orbicular, inflated to lenticular, 4-5 mm, glandless.
lenticular or terete, ensheathed by brownish or sometimes mottled persistent perianth;
embryo coiled.
and pistillate flowers usually on different plants.
= 10.
= 20, including 6 chromosomes concerned with sex determination.
Humulus japonicus
Humulus
Although I have no records from New Hampshire, the state is within the geographic range of Humulus japonicus.
Variegated forms of Humulus japonicus, cultivated as ornamentals, are sometimes spontaneous. The vernacular name Japanese hop(s) is occasionally misapplied to H. lupulus var. cordifolius (Miquel) Maximowicz, a variety not found in North America.
The disposition of the name Humulus scandens (Loureiro) Merrill, based on Antidesma scandens Loureiro, is problematic. E. D. Merrill (1935) was convinced that the name A. scandens applied to the species Humulus japonicus. If Merrill was correct, then the combination Humulus scandens would have priority. The material described by Loureiro, however, was not preserved, and his description does not coincide with that of H. japonicus. Humulus scandens is not included in synonymy in this treatment.
I. A. Grudzinskaya (1988) segregated Humulus japonicus as a new monotypic genus, Humulopsis, with the single species Humulopsis scandens (Loureiro) Grudzinskaya.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 3 (2 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Veins on abaxial surfaces of leaf blades pubescent, with stiff hairs; marginal areas of adaxial surfaces of younger leaf blades with stiff cystolithic hairs; petioles usually longer than blades; margins of pistillate bracteole densely ciliate-hairy; anthers without glands. | H. japonicus |
1. Veins on abaxial surfaces of leaf blades glabrous or with soft pubescence, without straight, erect hairs; marginal areas of adaxial surfaces of younger leaf blades with few or no cystolithic hairs; petioles usually shorter than blades; margins of pistillate bracteole not ciliate-hairy; anthers glandular. | H. lupulus |
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