Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/68

been accepted by Munro (1868) and Bentham (1878) in their most recent revisions of the Cape and Australian genera. The basis of Brown s division of the whole order into Panicece and Poacece is the position of the most perfect flower in the spikelet ; this is the upper (apparently) terminal one in the first, whilst in the second it occupies the lower position, the more imperfect ones (if any) being above it. Munro has supplemented this by another character easier of verification, and of even greater constancy, in the articulation of the pedicel in the Panicece immediately below the glumes; whilst in Poacece this does not occur, but the axis of the spikelet frequently articulates above the pair of empty basal glumes. Neither of these two great divisions will well accommodate certain genera allied to Phalaris, for which Brown proposed tentatively a third group (since named P/ialaridece); this, or at least the greater part of it, is placed by Bentham under the Poacece. The following arrangement is based on the writings of these authors, but it cannot be considered very satisfactory. Probably no serial disposition can represent the tangled network of genera related in different ways and various degrees which make up this very natural but complicated family, and though some of the following tribes are fairly natural, the limits of others are but ill-defined, and the position of many genera uncertain. I. PANICACE^E. Pedicel articulated below the glumes. Spikelet with one or two flowers, the more perfect fertile one above, the male or barren one, if present, below it. FIG. 8. Panicaceae. 1, a pair of spikelets of Andropogon; 2, spikeiet of Setaria, with an abortive branch beneath it. 1. Panicece. Spikelets with an apparently terminal hermaphrodite or female flower with or without a male one beneath it. Glumes three or four, the upper flowering one of a firm texture, the lowest usually small, sometimes absent. Awns rarely found ; if present, neither twisted nor kneed. Fruit enclosed in the hardened flowering glume and palea. EXAMPLES : Paspalum, Panicum, Setaria, Pennisetum, An- thephora, Thouarca, Spinlfex. 2. Tristerji iicce. Spikelets as in Panicece, but flowering-glume with a twisted and bent awn. EXAMPLES : Arundinclla, Tristachya, Pohjpogon(t). 3. Andropocjoncce. Spikelets as in the last, but usually in pairs (rarely three or solitary), one being sessile and fertile, the other stalkedandusuallymaleorneuter. Glumes four (rarely fewer), one of the outer ones the largest and enclosing the fruit, tire upper flowering one very thin and transparent, usually bear ing a twisted and bent awn or reduced to the awn. EXAMPLES : Ischcemwm, PoUinin, Andropogon, Imperata, Sorghum, Anthistiria, Erianthus, Eiilalla, Saccharum. 4. RoUloclliece. Spikelets as in the last ; one of each pair fertile, sessile, and sunk in alternate notches or cavities of the jointed simple rachis, the other stalked or absent ; no awns EXAMPLES -.Hemarthria, Manisuris, Rottbocliia, Opliiurus, Pnluna, Lcplarvs. 5. Mayadece. Spikelets monoecious, very unlike, the male numer ous in a terminal panicle, the female few at the base of the male inflorescence or more numerous in a separate one. EXAMPLES : Calx, Zea, Chionachnc, Tripsacum, Sclcrachne. II 6. Olyrccc. Spikelets monoecious, or some hermaphrodite and some male in the same panicle ; the flowering glume large, sometimes utricular. Stamens three, six, or more. Leaves often broad and petiolate. EXAMPLES : Lcptaspis, Diarus, Olyra, Pariana. . PHALAKIDEJE. Pedicel either articulated below the glumes or not, but the rachis of the spikelet articulated above the two lowest ones. Spikelets with (one or) three flowers, the perfect fertile one above, the two male, if present, below it. Two- nerved palea usually absent. EXAMPLES : Phalaris, Anthoxanthum, Ehrharta, Hicrochloe Alopecurus, Phkum, Cryjjsis, Lygcum (?). FIG. 9. Phalaridece. 1, spikelet of HierocJi oe; 2, spikelet of Anthoxanthum. III. POACE.E. Pedicel not articulated below the glumes. Rachis of spikelet often articulated above the two lowest glumes. Spikelets with one, two, or more fertile flowers, the male or imperfect ones (if any) above them. liachis of spikelet often continued as a point or bristle beyond the flowers. 1. Oryzcce. Spikelets one-flowered. Empty basal glumes very small or wanting. Two-nerved palea usually absent. Stamens usually six. EXAMPLES : Oryza, Lcersia, Potamophila, Zizania, Anotno- chloa (?). 2. StipccK. Spikelets one-flowered. Flowering glume with a terminal twisted and bent a vn. Palea small and thin. Lodicules three. EXAMPLES : Stipa, Aristida, Piptathcrum. 3. Agroslidccc. Spikelets one-flowered. Flowering glume usually with a terminal or dorsal bent awn. Palea small and thin. Lodicules two. EXAMPLES: Agrostis, Dcycuxia, Calamagrostis, Cokanthus(t). FIG. lO.Poacea;. 1, spikelet of Aji-usiis; 2, spikelet of Aira. 4. Avcnece. Spikeletsgenerally two- rarely three- or more-flowered. Flowering glumes with a terminal or dorsal bent and twisted awn. Palea large, enclosing with the flowering glume the fruit. EXAMPLES : Aira, TTolcus, Arrhenathcrum, Avena, Trisclum, Danthonia, Lagurus. [2, 3, and 4 together form Bentham s tribe Streptatherce. ] 5. Pappophorccc. Spikelets one- or several -flowered. Flowering glumes rounded on the back, terminating in three or more teeth often carried out into straight awns. EXAMPLES : Pappophorum, Triraphis, Cottca, Triodia. 6. CMoridecp. Spikelets one- or several-flowered, sessile on one sided spikes. Flowering glumes rarery awned.