British grasses and their employment in agriculture . Fig. 20. Median longitudinal section through the lower part of a wheat grain,showing the position and structure of the embryo. End. endosperm, in contact with the endosperm by Ep. the epithelial layer. growing apex, and Sad. the primary root of the embryo. Sh. the germ-sheath, Col. the root-sheath, Cap. the root-cap. x about 15. seed immediately above was borne. This is called the rachillaand lies in front of the inner palea at the base of the is the usual type of what is commonly called a grass some c
British grasses and their employment in agriculture . Fig. 20. Median longitudinal section through the lower part of a wheat grain,showing the position and structure of the embryo. End. endosperm, in contact with the endosperm by Ep. the epithelial layer. growing apex, and Sad. the primary root of the embryo. Sh. the germ-sheath, Col. the root-sheath, Cap. the root-cap. x about 15. seed immediately above was borne. This is called the rachillaand lies in front of the inner palea at the base of the is the usual type of what is commonly called a grass some cases however the seed consists of the entire spikelets, of the glumes, palese, and grain of one or more flowers, as in CH. I] The Morphology of Grasses 17 Holcus, Alopecurus, Panicum, In the genus Hordeum theso-called seeds often consist of the three united maturespikelets. In a few instances the seed consists of the grain. Kg. 21. I. Central cross-section of a grain of the cultivated Oat, Avena sativa, A small piece of the peripheral portion more highly magnified. 1 and 2,the pericarp; 3, testa; 4, remains of the nucellus; 5—7, amylaceous tissue;5, gluten cells; 6 and 7, cells of albumen containing compound starch-grains—at 7 they are richer in albumen and poor in starch; 8, fibro-vascular bundleof the seed-coat. Haiz. shed free from its paleae, as in the common varieties of Wheat,and sometimes Timothy-grass. 1 For other types see Anthoxanthum and Arrhenatherum. 2 18 Botanical Section [pti The naked grain of grasses forms a special type of fruit techni-cally known as a caryopsis. It is a one-seeded, dry, indehiscent1fruit, with the fruit-wall (pericarp) fused to the seed-coat (testa).The true seed then, consists of the embryo with its store ofendosperm, enclosed within the seed-coat. The thin fruit-wallsurrounding the seed-coat makes up the complete grain. Theembryo forms but a small portion o
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, booksubjectgr
