Silica deposition in the inflorescence bracts of wheat (Triticum aestivum). I. Scanning electron microscopy and light microscopy

摘要

Silica deposition in the lower glume, lemma, and palea of wheat (Triticum aestivumL. cv. Highbury) was investigated using scanning electron microscopy and light microscopy. Silica was present in the outer walls of all the epidermal cells including prickles and papillae of the glume and lemma awns. The glume and the lemma were similar in epidermal silica deposition pattern, both having numerous silicified short trichomes and papillae on inner and outer surfaces. Epidermal long cells and short cells were also silicified. Macrohairs were restricted to isolated areas in these bracts, particularly on the inner surfaces just beneath the awns. The palea was a thin membranous structure differing markedly from the other two bracts. Most of the palea is pressed between the caryopsis and the next floret, and both surfaces are almost devoid of trichomes in these areas. However, at the apex and margins of the palea, macrohairs and papillae were abundant. The results are discussed with respect to possible taxonomic, anatomical, medical, and archaeological implications.