Cannabinaceae is the family of plants that contains both Cannabis and Humulus genera. Within the Humulus genus there are two species including humulus lupulus and and humulus japonicus. Humulus japonicus, is sometimes referred to as japanese hops and is a climbing vine originating from east Asia. Humulus japonicus is considered invasive, as it grows quickly and easily. This type is of no interest to a brewer, as its flowers do not contain the bitterness or aroma desired in beer. In 1978 a third species was identified by Ernest Small and is now known as Humulus yunnanensis. This variety is often misidentified as Humulus lupulus. Hops a.k.a Humulus lupulus rolls off the tongue when you say it. For brewing beer, hops is filled with flowery resins and oils that compliment the sweets of barley and wheat perfectly. There are five species of Humulus lupulus including lupulus, cordifolius, lupuloides, neomexicanus, and pubescens.
Hops is believed to have originated from Asia, and originally grew mainly in the Northern Hemisphere. It is now grown around the world in both hemispheres in temperate zones from 35-50 degrees North and 25-45 degrees South.. From the Holdridge Life Zones perspective, defined by the IIASA, hops will flourish from Subtropical Dry Forest to the Boreal Wet Forest. Hops plants are very hardy and can tolerate sub-zero Fahrenheit temperatures when dormant. During the growing stages in the spring, however, the shoots can be damaged by even mild frost. In order for the hops plant to produce flowers (cones), at least 120 days above frosting temperatures are required.
Hops itself is the name of the female flower cones, which are also known as strobiles. Strobiles are the names given to seeds and flowers of hops plants that produce a cone-like structure with overlapping spore producing leaves or sporophylls. These leaves are spirally arranged along a central core. And in as much, hops resembles tiny pine cones, although to the touch is more like soft paper than hard wood. Deep within the cone are the pungent resins and oils that give this plant its reputation. This reputation is as synonymous as brewing beer itself. Even the mildest of beers would seem crippled and off the mark without hops to most beer drinkers.
Humulus lupulus is a hardy vigorous perennial climber that can live up to 20 years. Hops is a herbaceous vine that prefers moist and rich soils, although can be somewhat drought tolerant after it has been established due to its deep rooting nature. Roots can grow as deep as 15 feet over the life of the plant which is deeper than many trees. The root ball or crown grows in mass and shape through the years. Hops roots resembles a dark form of ginger root and is the heart for the production of both vertical and horizontal roots.
Hops has both male and female plants and thus male and female flowers. The species is dioecious meaning the male plant (androecious) produces microspores in its flowers, while the female plant (gynoecious) produces the megaspores. The male hops plants lack the concentration of oils and resins, and leave them better for breeding and for ornamental planting than for producing beer. The male plants produce a great deal of pollen which can be used used to pollinate an entire field of female plants. This type of propagation can be used to produce seeds for future seasons. This is also valuable for cross pollinating to create new strains but is better for controlled environments vs. the wide open. The result for the female flowers of hops is an increase in mass and size of the flowers. When traded commercially this creates a negative side effect as the additional weight adds no value to the brewer as the seeds are not beneficial for bitterness or aroma. Hops seeds are fairly easily available and can be ordered online.
Aside from the seed generating capabilities of the plant, hops produces rhizomes. Rhizomes are underground shoots from the crown the contain both buds and rootlets. These rhizomes are the more common means for vegetative reproduction both practically at home, and through hops distributors as the sex of the plant is already determined.
Check out the next section on hops planting location and trellis design...