254 GR AMINES. 



Grasses are widely distributed from equatorial to arctic regions, some genera especially abundant 

 in the tropics, but the majority belonging to the temperate zones. In the number of individuals 

 they probably exceed all other flowering plants, while in the number of species the family stands 

 third, the first and second places belonging to Composites and Leguminosce. In usefulness to 

 man they easily take the first rank, as they are at the foundation of all agriculture, their herbage 

 affording the larger share of the food of animals, while their seeds supply, in the cereal grains, 

 the chief food of the world. Rice, Durra, Maize, Wheat, Rye, Oats, Barley, and Sugar-Cane, 

 need only to be mentioned to show the economical importance of the family. It is a singular fact 

 that the most useful of the family, those which furnish the cereal grains, are none of them known 

 with certainty in the wild state, even their native countries being in doubt. But few grasses 

 present marked properties. Anthoxanthum, Jfierochloe, and a few others, have a pleasant Va- 

 nilla-like odor, due to a principle like coumarin. Some oriental species of Andropoyon afford in 

 their foliage the oils of Lernon-Grass, Citronella, and Geranium, and from the roots of another 

 species is obtained the perfume " Vettiver." The rhizomes of Trif.icum repens and of Cynodon 

 Dacty/on have long had a reputation for usefulness in diseases of the bladder. The many uses 

 which the stems of species of Bambusa, the Bamboos, are made to serve in China and other eastern 

 countries give them a high rank among the useful grasses. In ornamental gardening, besides 

 furnishing the carpet of verdure without which our gardens would lose much of their attrac- 

 tiveness, grasses play an important part. From the humble Festuca glauca, the striking blue 

 foliage of which is used for edgings, up to the stately Gynerium argcnlcum, the Pampas -Grass, 

 the list of ornamental species and varieties is a long one. 



In describing the structure of the spikelets, both Bentham and Hooker make use of different 

 terms from those here given. They designate the glumes as " empty glumes," and the lower palct 

 as the "flowering glume," while they have but a single "palet," which is our upper palet. The 

 usual terminology is here followed, as the one universally taught in our text-books, and as not 

 involving any theoretical views of the structure of the flowers. In the grouping of the genera of 

 this immense family into snbgenera, or into tribes and subtribes, botanists differ widely, accord- 

 ing to the prominence given by the authors to particular characters. The arrangement here 

 presented is not made to express any views as to the relationship of the genera, but solely with 

 the object of leading the student to the genus by the most direct path. 



TRIBE I. PANICACE^E. Spikelet articulated with the pedicel below the glumes, mostly 

 2-flowered : one flower fertile ; the staminate or barren floret, when present, below it. 



Subtribe I. PANICE^E. Spikelets of one terminal perfect floret with an imperfect (stami- 

 nate or neutral) one below it, the latter often reduced to a single palet ; sometimes appear- 

 ing as if 1 -flowered by the suppression of the lower glume and the upper palet of the neutral 

 floret. Grain inclosed in the coriaceous or chartaceous palets of the perfect floret. 



* Spikelets apparently 1 -flowered by absence of the lower glume, the palet of the neutral floret 



taking its place. 



1. Paspalum. Spikelets plano-convex, on one side of a flattened rhachis. 



* * Spikelets 1- or 2-flowered : lower floret staminate or neuter, of 1 or 2 palets. 



2. Fanicum. Spikelets without an involucre. Lower glume usually minute. 



3. Setaria. Spikelets with an involucre of bristles proceeding from the pedicels. 



4. Cenchrus. Spikelets inclosed, 1 to 3 together, in a hard bristly or spiny bur-like involucre. 



Subtribe II. ANDROPOGONE^E. Spikelets in pairs, very dissimilar, one rudimentary. 

 Palets of the fertile floret scarious, thinner than the indurated glumes. 



5. Ischaemum. Spikelets on one side of a single spike. 



TKIBE II. PHALARIDE^E. Spikelets not articulated below the glumes, of one terminal per- 

 fect flower, or with two male or neutral or rudimentary florets below the perfect one. 

 Spikelets laterally compressed. Glumes sometimes united below. 

 * Glumes wanting : inflorescence panicled. 



6. Leersia. Spikelets much flattened. Palets rigid. Stamens 1 to 3 or 6. 



* * Glumes present. 

 +- Spikelets 1-flowered, densely spiked : glumes equal, boat-shaped, strongly keeled. 



7. Alopecurus. Glumes united at base. Lower palet awned, upper wanting. 



8. Fhleum. Glumes distinct. Lower palet avvnless, upper present. 



+- +- Spikelets 1 - 2-flowered, panicled. 



9. Beckmannia. Spikelets (ours 1-flowered) crowded in two rows upon the branches. 



+ +- +- Spikelets 3-flovvered, the lateral staminate or neutral : plant sweet-scented. 



1 0. Hierochloe. Lateral florets staminate. Panicle loose. 



11. Anthoxanthum. Lateral florets neutral, of a single awned hairy palet. 



