Page:Encyclopædia Britannica, Ninth Edition, v. 11.djvu/66

Rh inner ones flattened out so as to form a very hard globular spiny case to the spikelets. The cup-shaped involucre of Cornucopice is a dilatation of the axis into a hollow recep tacle with a raised border. In Cynosurus the pectinate involucre which conceals the spikelet is a barren or abortive spikelet. True bracts of a more general character subtend ing branches of the inflorescence are singularly rare in Grarninece, in mirked contrast with Cyperacece, where they are so conspicuous. They however occur in a whole sec tion of Andropogon, in Anomochloa, and at the base of the spike in Sesleria. The remarkable ovoid involucre of Coix, which becomes of stony hardness, white, and polished (then known as &quot; Job s tears &quot;), is also a modified bract or leaf-sheath. It is entirely closed except at the apex, and contiins the female spikelet, the stalks of the male inflorescence and the long styles emerging through the sin ill apical orifice. Any number of spikelets may compose the inflorescence, and their arrangement is very various. In the spicate forms, with sessile spikelets on the main axis, the latter is often dilated and flattened (Paspalum), or is more or less thickened and hollowed out (Stenotaphrum, Rottboellia, Tripsacum), when the spikelets are sunk and buried within the cavities. Every variety of racemose and paniculate inflorescence obtains, and the number of spikelets composing those of the large kinds is often immense. Rarely the inflorescence consists of very few flowers; thus Lygeum Spartum, the most anomalous of European grasses, has but two or three large uniflorous spikelets, which are fused together at the base, and have no basal glumes, but are enveloped in a large hooded spathe-like bract.

Flower.&mdash;This is characterized by remarkable uniformity. The perianth is represented by very rudimentary, small, fleshy, hypogynous scales called lodicules (&quot; squamulae,&quot;

&mdash;Flowers of Grasses.1, Piptatherum, with the palea; 2, Poa; 3, Oryza''.

Kunth ; &quot; nectarium,&quot; Schreber) ; they are elongated or truncate, sometimes fringed with hairs, and are in contact with the ovary. Their usual number is two, and they are placed collaterally at the anterior side of the flower, that is, within the flowering glume. They are generally considered | to represent the inner whorl of the ordinary monocoty- ! ledonoas (liliaceous) perianth, the outer whorl of these | being suppressed as well as the posterior member of the inner whorl. This latter is present almost constantly in Stipeoe and Bambusece, which have three lodicules, and in the latter group they are occasionally more numerous (five, spreading and persistent in Pseudostachyum ; six to eight in Beesha). In Anomochloa they are represented by hairs. In Streptochvte, according to Doll, there are six lodicules, alternately arranged in two whorls. They are often quite absent. In some cases lodicules are of the nature of stipules to the palea, and appear as though split off from its sides at the base. Such stipular lodicules often co-exist along with the perianthial ones, and are then either free from of combined with the two anterior ones.

Sexual Organs.&mdash;Grass-flowers are usually hermaphrodite, but there are very many exceptions. Thus it is very common to find one or more imperfect (usually male) flowers in the same spikelet with bisexual ones, and their relative position is important in classification. Holcus and Arrhen- a,theruin are examples in English grasses; and as a rule in species of temperate regions separation of the sexes is not carried further. In warmer countries monoecious and dioecious grasses are more frequent. In such cases the male and female spikelets and inflorescence may be very dissimilar, as in the maize, Job s tears, Euchlaena, Spinifex, itc.; and in some dioecious species this dissimilarity has led to the two sexes being referred to different genera (e.g., Antephora axilliftora, Steud., is the female of Buchloe dactyloides, Engelm., and Nenrachne paradoxa, Br., of a species of Spinifex). In other grasses, however, with the sexes in different plants (e.g., Brizopyrum, Distichlis, Era- grostis capitata, Gynerium), no such dimorphism obtains. A mphicarpum is remarkable in having cleistogamic flowers borne on long radical subterranean peduncles which are fertile, whilst the conspicuous upper paniculate ones, though apparently perfect, never produce fruit. Something similar occurs in Leersia oryzoides, where the fertile spikelets are concealed within the leaf-sheaths.

Andrœcium.&mdash;In the vast majority there are three stamens alternating with the lodicules, and therefore one anterior, i.e., opposite the flowering glume, the other two being pos- terior and in contact with the palea. They are hypogynous, and have long and very delicate filaments, and large, linear or oblong two-celled anthers, dorsifixed and ultimately very versatile, deeply indented at each end, and commonly exsertecl and pendulous. Suppression of the anterior stamen sometimes occurs (e.g., Anthoxanthum), or the two posterior ones may be absent (Uniola, Cinna, Phippsia, Festuca bromoides). On the other hand there is in some genera (Oryza, most Bambuseai) another row of three stamens, making six in all (fig. 3, 3); and Anomochloa and Telrarrhena possess four. The stamens become numerous (ten to forty) in the male flowers of a few monoecious genera (Pariana, Luziola}. In Beesha they vary from seven to thirty, and in Gigantochloa they are monadelphous.

Gynœcium.&mdash;There is but little variation here from a bicarpellary pistil, with a small rounded one-celled ovary containing a single laterally attached or ascending ovule, capped by two styles quite distinct or connate at the base,

&mdash;Pistils of Grasses.1, Alopecurus; 2, Bromus; 3, Arrhenatherum; 4, Glyceria; 5, Melica; 6, Mibora; 7, Nardus.

and with densely hairy or feathery stigmaa (fig. 4). Occa sionally there is but a single style (Nardus, Lygeum), and this may attain to a great length (6 inches in the maize); or three styles may be present (some Bambusece, Leptaspis, Streptochaete). Nees has described a case in which three complete carpels were found in Schedonorus elatior. 