GRA 



GRA 



GRASS, in botany. Tke tribe of grass- 

 es in one of the seven natural families in- 

 to which all vegetables are distributed by 

 Linnaeus, in his ' Philosophia Botanica." 

 They are denned to be plants which have 

 very simple leaves, a jointed stem, a 

 husky calyx, named a glume, and a single 

 seed. This description includes corn as 

 well as the grasses. 



Most of these plants are annual or pe- 

 rennial herbs ; some of them are erect, 

 Others creep upon the ground. The 

 roots, in the greatest number creep, and 

 emit fibres from each knot or joint ; in 

 others, they are simply branched and 

 fibrous. The stems and branches are 

 round: the leaves are simple, alternate, 

 entire, very long; and commonly narrow; 

 they are generally placed immediately 

 upon the stem, except in the bamboo, 

 and a few others, which have a foot stalk 

 at the origin of the leaves. The leaves 

 form below a sort of sheath, which em- 

 braces the stem, and is generally cleft on 

 one side through its whole length. The 

 top of the sheath is sometimes crowned 

 with a membrane, that is either cleft or 

 entire, and is frequently accompanied 

 with two appendages or ears, as in rice, 

 pharus, darnel, wheat, rye, and barley. 

 In others, the sheath is crowned with 

 hairs, as in millet, panic-grass, and andro- 

 pogon, and in some species of panic- 

 grass it is naked,that is, has neither mem- 

 brane nor hairs. There are three sec- 

 tions. The flowers are hermaphrodite 

 in plants of the first section ; male and 

 female upon the same root in those of the 

 second ; hermaphrodite and male on the 

 same root in those of the third. They 

 proceed either singly from the sheath of 

 the leaves, as in lygeum ; form a single 

 spike, as in nardus and darnel ; or are 

 formed into a panicle, that is, loose spike, 

 as in poa, agrestis, and oats. The calyx 

 and corolla in this order are not suffi- 

 ciently ascertained. In some a single 

 scale or husk, in others two, as in nardus, 

 supply the place of both covers ; some 

 grasses, as canary-grass, and phleum, 

 have four husky scales, two of which 

 serve for the calyx, and the other two for 

 the corolla ; some have five, as anthoxan- 

 thum ; others six, as rice, four of which 

 are supposed to constitute the calyx, and 

 the other two are termed, improperly 

 enough, the husky petals. The corolla 

 is sometimes composed of one petal with 

 two divisions, as in fox-tail grass. The 

 stamina are generally three in number, 

 and placed irregularly with respect to 

 the situation of the calyx and corolla. 

 One stamen is commonly placed betwixt 

 VOL. VI. 



the seed bud and the two small scales or 

 external husk of the corolla ; and two be- 

 twixt the seed bud and the inner husk. 

 Rice, zizania, and pharus, have six stami- 

 na. The anthers are long, furnished 

 with two cells, and slightly attached to 

 the filaments. The seed bud is placed 

 upon the same receptacle as the calyx, 

 corolla, and stamina. In bobartia it is 

 said to be placed under the receptacle 

 of the flower. The style is generally dou- 

 ble, and crowned with a hairy stigma or 

 summit. The seed vessel in this order 

 is wanting. The seeds are single, oval, 

 and attached below to the bottom of the 

 flower. 



GRATIOLA, in botany, a genus of the 

 Diandria Monogynia class and order. Na- 

 tural order of Personatae. Scrophulariae, 

 Jussieu. Essential character: calyx seven- 

 leaved, the two outer leaves petalous ; 

 corolla irregular, reversed ; stamens two, 

 barren ; capsule two celled. There are 

 twelve species. 



GRAVE, in music, is applied to a sound 

 which is of alow or deep tone. The thick- 

 er the cord or string, the more grave is 

 the note or tone; and smaller, the more 

 acute. The gravity of sounds depends 

 on the slowness of the vibratory motions 

 of the chord ; and their acuteness on its- 

 quick vibrations. Grave, in the Italian 

 music, denotes a very grave and slow mo- 

 tion, somewhat faster than adagio, and 

 slower than largo. 



GRAVE accent, in grammar, shews that, 

 the voice is to be lowered ; its mark 

 stands thus v . See ACCENT. 



GRAVE digging beetle. See SILPHA. 

 GRAVEL, in natural history and gar- 

 dening, a congeries of pebbles, which, 

 mixed with a stiff loam, makes lasting 

 and elegant gravel walks, an ornament 

 peculiar to our gardens, -and which gives 

 them the advantage over those of other 

 nations. 



GRAVER, in the art of engraving, a 

 tool by which all the lines, scratches, and 

 shades, are cut in copper, &c. Gravers 

 are of three sorts, round-pointed, square- 

 pointed, and lozenge. The round are 

 the best for scratching; the square-point- 

 ed are for cutting the largest strokes, 

 and the lozenge-pointed-ones for the 

 most fine and delicate strokes ; but a 

 graver of a middle form, between the 

 square and lozenge-pointed, will make 

 the strokes or scratches appear with 

 more life and vigour. See EireRAYiire. 

 GRAVIMETER, the name given by 

 M. Guyton to an instrument for measur- 

 ing specific gravities : he adopts this 

 name rather than either aerometer or hy- 

 I 



