Barley for Food and Health: Science, Technology, and Products

20 BARLEY: TAXONOMY, MORPHOLOGY, AND ANATOMY
ancestor of cultivated barley was the progenitor of H. v. spontaneum and that this
ancestor plant is extinct and no longer exists in the modern world. Harlan suggested
that the line of development of barley began with the unknown but closely
related plant of H. spontaneum, which was eventually transformed through mutations
into H. vulgare. The morphological variability seen in cultivated barley has
been ascribed to changes occurring during cultivation over an extended period of
time in a wide array of geographical areas and to intense breeding (Wiebe and
Reid 1961).
The position of barley within the Poaceae (grass family) is of interest from
the evolutionary viewpoint but also reveals the important relationship with other
members of the Triticeae tribe, rye (Secale cereale) andwheat(Triticum spp.).
Taxonomic classification of barley not only reveals these relationships but also
allows the identification of barley types and varieties from the morphological
characteristics of the plant and grain. The chief identifying taxonomic characteristic
of Hordeum is its one-flower spikelet, three of which alternate on opposite
sides of each node of the flat rachis, forming a triplet of spikelets at each node.
There are one central and two lateral spikelets. All three spikelets may be fertile
(six-rowed) or only the central spikelet is fertile (two-rowed) (Figure 2.1). The
taxonomic descriptions of the genus Hordeum as presented is a basic introduction
to the science. A detailed description of barley taxonomy, morphology, ecology,
and distribution of the various species of Hordeum may be found in publications
by Bothmer and Jacobsen (1985), Reid (1985), Bothmer (1992), and Moral
et al. (2002).
FIGURE 2.1 Barley heads. Left: front and side view of six-rowed barley. Right: front
and side view of two-rowed barley. (Courtesy of American Malting Barley Association.)