Barley for Food and Health: Science, Technology, and Products
Barley for Food and Health: Science, Technology, and Products
Barley for Food and Health: Science, Technology, and Products
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
24 BARLEY: TAXONOMY, MORPHOLOGY, AND ANATOMY<br />
clawlike appendages that clasp the stem, are located at the juncture (top) of the<br />
leaf sheath <strong>and</strong> the blade. The ligule is an appendage also located at the juncture<br />
of the leaf sheaf <strong>and</strong> blade extending upward along the stem <strong>and</strong> varies in size<br />
with barley type. The ligule <strong>and</strong> auricles are absent in some barleys. In addition<br />
to providing leaf attachment, the leaf sheaf also provides strength <strong>and</strong> support<br />
to the stem. The angle of attachment of the leaf to the stem varies from erect to<br />
drooping, depending on the cultivar.<br />
Because of the chlorophyll, the leaf of normal barley is completely green,<br />
but chlorophyll content varies <strong>and</strong> in extreme cases is so low that the plant is<br />
considered an albino. Chlorophyll content is highly correlated with plant survival.<br />
The green color of normal barley is intensified by fertilizer, especially nitrogen<br />
fertilizer. A red to purple color, due to an anthocyanin pigment, occurs in the<br />
sheaths at the base of the plant. The color is enhanced by cold weather. In most<br />
barley, the leaf <strong>and</strong> leaf sheath surfaces are covered by a chalklike substance that<br />
creates a waxy appearance. In barleys having less or none of this substance, the<br />
plant has a glossy appearance.<br />
Spike<br />
The inflorescence (flower head) of barley, termed the spike, isclassedasanindeterminate<br />
inflorescence because the axis (rachis) does not terminate in a spikelet.<br />
The barley spike, located at the tip of the stem neck, consists of varying numbers<br />
of spikelets attached at the nodes of a solid, flat, zigzag rachis (Figure 2.4). <strong>Barley</strong><br />
flowers are complete flowers, containing both the ovule <strong>and</strong> the anthers <strong>and</strong> are<br />
mostly self- pollinated. Spikelets are single flowered, consisting of two glumes<br />
<strong>and</strong> a floret in which the kernel develops following fertilization. There are three<br />
spikelets attached at each node on the rachis, alternating from side to side. All<br />
three spikelets are fertile in six-rowed barleys, whereas only the central spikelet is<br />
Rachis<br />
Two-row barley spike<br />
single rachis node, back view<br />
Six-row barley spike<br />
Single rachis node, back view<br />
Examples of<br />
rachis nodes<br />
FIGURE 2.4<br />
Spikes <strong>and</strong> rachies of barley. (From brewingtechniques.com.)
Change language