Wild relatives offer a diversity of traits potentially useful in crop improvement. Identification of major genes for resistance to biotic and abiotic stresses, in conjunction with targeted introgression, has introduced some of these traits into cultivated varieties. The difficulty of transferring complex traits, and associated linkage drag, has limited the ability of breeding programs to fully use important genetic variation. Wheat (Triticum L.) is an example of an important crop with large secondary and tertiary genepools of species capable of producing viable offspring by cross pollination. Wheat is annual, but most of the related species in the Triticeae Dumort tribe are perennials. An unknown number of genes control the perennial habit, although previous work has shown that it is a complex trait with quantitative expression. Lack of recombination between the parental genomes and complexity of the trait suggest another avenue for breeding: the addition of a genome. Multiple genera can hybridize with wheat, and some combinations produce stable amphiploids. The development of perennial grain and forage crops balancing the agronomics of wheat with the polycarpic habit of its relatives is promising. The approach is similar to Triticale (× Triticosecale Wittmack ex A. Camus), where new crops are developed combining the desirable qualities of the parents. Through prebreeding of the wild relatives, application of insight into meiosis, and strategic use of known genes, it should be more efficient to breed perennial grain crops adapted to diverse production systems.

Nearly a century has passed since the first crosses were made between wheat (Triticum L.) and perennial Triticeae relatives with the goal of developing a perennial grain and forage crop. Numerous crosses of different species and genera have been attempted, and many have yielded fertile hybrids. Despite these successes, a definitive taxonomic treatment of stable hybrids has never been established. ''Perennial wheat'' is the term commonly used to refer to these hybrids when the traits of interest are the perennial growth habit and grain yield, regardless of parentage. In order to establish a consistent system in which researchers can effectively communicate and collaborate, it is important to characterize unique combinations. In this paper we briefly outline the history of perennial wheat breeding, suggest a naming convention based on the International Code for Nomenclature and describe one combination within the new nothogenus 9Tritipyrum. The development of perennial grains has the potential to allow for new agricultural systems that take advantage of the persistent nature of the crop. The taxonomic definition of this new crop type will help focus research and breeding efforts as well as organize the literature and facilitate collaboration.

Malted grains—principally barley (Hordeum vulgare L.) —are essential raw materials for brewing. There is an increasing demand for more sustainable crop production practices. At the same time, climate change makes it imperative to identify new production zones, systems, and crops. These demands and imperatives have stimulated interest in converting staple cereal crops, including barley, from annual to perennial growth habit. Most effort has been devoted to wheat (Triticum aestivum L.), and the most progress made in domesticating a perennial relative of wheat. These results prompt the questions: what are the prospects for developing perennial malting barley and is developing perennial malting barley the most direct path to sustainability? Malting barley is a challenge for growth habit conversion due to stringent quality parameters and the extensive infrastructure required for production, processing, and distribution. We discuss four possible paths to achieving the conversion from annual to perennial growth habit while maintaining expected levels of malting quality and agronomic performance: direct domestication, wide hybridization, manipulation of the vernalization and photoperiod sensitivity genes, and mapping annual and perennial forms of ryegrass (Lolium multiflorum L., and L. perenne. L, respectively) as a basis to identify genes conferring perenniality. We conclude that any one of these approaches would require significant, long‐term investment. Until such investment is forthcoming, we conclude that there are more cost‐effective, short‐term solutions—notably no‐till, multiple cropping, and increased emphasis on fall‐seeded barley—that could enhance the sustainability and viability of annual malting barley production.