Transverse section of shoot, 15, 16 _Triodia_--Heath-grass, 11, 14, 19, 25, 26, 90, 91, 103, 139; _T. decumbens_, 8, 29, 34, +110+, _123_ _Trisetum flavescens_--_Avena flavescens_ _Triticum_--Wheat; _T. acutum_--_T. laxum_; _T. junceum_--_Agropyrum junceum_; _T. laxum_--_Agropyrum laxum_; _T. pungens_--_T. laxum;_ _T. repens_--_Agropyrum repens_ Tropical species, 1, 2 Truncate, 92, 142 Tuber, 8 Tufted grasses, 13, 14 Tufted Hair-grass--_Aira cæspitosa_ Tufted inflorescences, 90, 99, 102, 103, 109 Tufts, _5_, _9_, 12, 13, 37 Tumble-weeds, 125 Turgescence--the distension of cells with water which they have absorbed, 63 Tussocks, 13 Twisted awns, 116, 125, _126_, _129_, 130, 151, 154, _158_ Twisting of seedling leaves, 133 Twitch--certain persistent weeds belonging to the genera _Agropyrum_, _Agrostis_, _Holcus_, etc.: _see_ Couch-grass, 52, 57, 59 Two-flowered spikelets, 90 +U+-shaped leaf-sections, 20 _Uniola_, 97 Upright Brome--_Bromus erectus_. Also _B. madritensis_ Uses of grasses, 1, 2 +V+-shaped leaf-sections, 20, 53, 73 Vagabond grasses, 29, 32, 34 Variability, 26 Vascular bundles, 21, 22, 62, _63_, _64_, _65_, _66_, _67_, +68+, _69_, 70, _71_, 75, 76, 78, 80, 81 Vascular-bundle sheath, 68, 95, _122_ Vegetative organs, 4 Veins, 18, 21, 22, 68, 76, 91 Venation, +21+, 62, +67+, 68 Vermin, 35 Vernal grass--_Anthoxanthum_, 83 Vernation--folding of the leaves in bud, 21 Versatile--hung loosely so as to turn freely, 94 Vessels, 67 Violet-brown sheath, 18 Viviparous grasses, 112, 114, 134 _Vulpia Myurus_--_Festuca Myurus_; _V. uniglumis_--_Festuca uniglumis_ Wall Barley--_Hordeum murinum_ Wall Fescue--_Festuca Myurus_ Walls, grasses of, 29 Waste-places, 29 Water-storing tissues, 36, 70 Water Whorl-grass--_Catabrosa aquatica_ Wavy Hair-grass--_Aira flexuosa_ Wavy Meadow-grass--_Poa laxa_ Wax, 36, 70 Web--minute tufted soft hairs at the base of the caryopsis, 113, 114, _127_, 131, 138, 139, _140_, 141 Weeds, 27, 28, 29, 35 Wheat--_Triticum_, 1, 120, 127, 132, +133+ Wheat-grass--_Agropyrum_ Whorl-grass--_Catabrosa_ Wild Oat--_Avena fatua_, 117 Wind-borne seeds, 125, _126_ Wings, 125, 142 Wood Barley--_Hordeum sylvaticum_ Wood False-Brome--_Brachypodium sylvaticum_ Wood Meadow-grass--_Poa nemoralis_ Wood Melick--_Melica uniflora_ Wood Poa--_Poa nemoralis_ Wood-species, +28+, 33 Woolly Holcus--_Holcus lanatus_ Xenia--cases where the direct influence of the pollen is evident on the seed resulting from its action, 120 Xerophilous--of the nature of a xerophyte, 70 Xerophytes--plants adapted to dry situations, 24, 25, 36, 37, 38, 68, 70 Xylem, 67 Yellow Oat-grass--_Avena flavescens_ Yellow-sheathed grasses, 18 Yorkshire Fog--_Holcus lanatus_, 152 _Zostera_, 3