Narrow-leafed Oat--_Avena pratensis_ Narrow Small-reed--_Calamagrostis stricta_ Naviculate--Boat-shaped, but pointed at both ends, 16 Nematode worms, 10 Nerves--minute veins on paleæ, 113, 115, _128_, _140_, 144, 168 Nodes, 6, 8, 12, 14, 15 Nodules, 10 Northern Holy-grass--_Hierochloe borealis_ Nucellus--the body of the ovule or young seed, _122_ Nuclei, 121 Numbers of grasses, 2 Oat--_Avena_, 85, 89, +133+ Oat-type of “seed,” 156 Obsolete--so much reduced as to be practically absent, 19, 45, 48, 115, 116 Obtuse--rounded off and blunt at the apex, 19, 91 Odours, 27 Offsets, 12 _Olyra_, 6 One-flowered spikelets, 89 One-glumed Fescue--_Festuca uniglumis_ Open panicle--one where the primary branches stand off at right angles from the rachis, 112 Orange spiked Foxtail--_Alopecurus fulvus_ Orchids, 2 Ovary, 86, _87_, 89, 95, _96_, 97, 119, 121 Ovate-acute--egg-shaped in outline, but the free narrow end pointed, 61 Ovate-lanceolate--ovate, but tapering above, 168 Pale--Palea, 86, 89 Palea, _84_, _85_, 86, _87_, +92+, _93_, 95, _96_, 97, 99-118, 119, 120, _124_, 125, 127, _128_, _129_, 130, 131, 134, +135+-+174+ Pampas-grass, 1 Panic-grass--_Panicum_ Panicle, _5_, _12_, 87, 88, 90, 91, 103, 105, 109-118 _Panicum_, 4, 19, 67, 69, 72, 87, 90, 92, 101, 105, 109, 124, 135, 136, 137, 142; _P. Crus-galli_, 137; _P. glaucum_, 30; _P. plicatum_, 21; _P. sanguinale_, 30; _P. verticillatum_, 30 Papillæ--protruding cells not long enough to be termed hairs, 64, 67 Pappus, 125 Parallel venation, 21, 22 Parenchyma--ordinary soft cellular tissue of herbaceous parts, 64, 65 Partial inflorescence, 86 Pasture, 1, 10 Pasture-grasses, +27+, +28+, 37 Perennial Beard-grass--_Polypogon littoralis_ Perennial grasses, 10, 11, 40, 43, 58, 114 Perennial Oat--_Avena pratensis_ Perennial Oat-grass--_Avena pratensis_ Perfect flowers, 89, 90, 99, 100, 105, 106 Perianth--the floral coverings, 96 Pericarp--the coats of the true fruit, _121_, _122_ Petiole, 5, 17 _Phalaris_--Canary grass, 88, 101, 109, 136; _P. arundinacea_--_Digraphis arundinacea_; _P. canariensis_, 31, 139 _Phleum_, 66, 88, 89, 90, 91, 93, +102+, 109, 110, 136, 137, 142; _P. alpinum_, 30, 102; _P. arenarium_, 7, 10, 29, 37, +55+, +102+, 136; _P. asperum_, 31, 55, 102, 136; _P. Bœhmeri_, 8, 31, 55, 102, 136; _P. nodosum_--var. of _P. pratense_; _P. phalaroides_--_P. Bœhmeri_; _P. pratense_, 7, 8, 11, 13, 25, 28, 32, +55+, 70, +76+, +102+, _128_, +135+ Phloem, 67 _Phragmites communis_--_Arundo Phragmites_ Physiognomy, 36, 37 Piercing of soil, 132 Pilose--with scattered, rather long soft hairs, 59 Plaited vernation, 21 _Plantago_, 3 Plicate--plaited Plume-like inflorescence, 91, 103 Plumule, _121_, 123, 132, 133