477. Anthoxanthum. - Spikelets in spike-like panicle, interrupted; glumes unequal, awned, 6, third and fourth empty; stamens 2; paleae leathery, unequal.

478. Hierochloe. - Spikelets in an open panicle; upper floret perfect; 2 lower male, 3-androus, awnless; ovary smooth.

479. Alopecurus. - Spikelets in dense, cylindrical spike, jointed on pedicel; glumes 6, awnless; paleae awned, I-nerved.

480. Milium. - Panicle spreading; spikelets stalked; rachilla not produced beyond flowering glume; glumes equal; paleae awnless; flowering glume hardening round fruit.

481. Phleum. - Spikelets in dense, cylindrical spike, or panicle; flowering glume enclosing the fruit; paleae awned, 2-nerved, glumes 3.

482. Mibora (Knappia). - Spike simple; spikelets dorsally compressed, solitary, one-sided, 1-flowered; glumes blunt; palea membranous, shaggy, truncate, awnless.

483. Agrostis. - Spikelets in loose panicle; flowering glume small, hyaline; glumes unequal, upper smaller; outer paleae awnless.

484. Polypogon. - Spikelets in close contracted spike-like panicle; glumes with long bristles, membranous, lower palea awned from just below tip.

485. Calamagrostis. - Panicle spreading; rachilla with long silky hairs; glumes subequal; lower palea awned.

486. Deyeuxia. - Panicle close, spike-like; glumes equal; rachis ciliate, longer than flowering glume; empty glumes large; flowering glumes awned.

487. Gastridium. - Panicle close, spike-like; rachilla produced beyond flowering glume; glumes acute, awnless; empty glumes large, boat-shaped; flowering glume small, 4-toothed.

488. Apera. - Panicle loose; glumes acute, awnless, unequal, lower smaller; outer paleae awned; flowering glume 2-fid, awned; empty glumes large.

489. Ammophila. - Spike cylindrical, large; spikelets large; glumes subequal, lower shorter; paleae hairy below; rachilla long, silky.

490. Lagurus. - Spike ovate; glumes with long bristles; empty glume plumose; flowering glume 3-awned; lower palea with 2 bristles and twisted awn.

491. Aira. - Spikelets in loose panicle; rachilla not produced beyond uppermost flowering glume; awn dorsal, twisted, lower paleae 2-fid; glumes equalling lower floret.

492. Corynephorus (Weingoertneria). - Florets 2, awned; awn straight, jointed, upper part club-shaped, tuft of hairs at junction.

493. Deschampsia. - Florets 2; awn straight, rachilla longer than upper flowering glume; lower palea jagged.

494. Holcus. - Florets 2; lower perfect, awnless; upper male, with dorsal awn; paleae hardening on fruit.

495. Trisetum. - Florets 2-6 in spikelet, crowded; flowering glume 2-fid, awned; awn twisted; ovary smooth; fruit not crested.

496. Avena. - Florets 2-6'; glumes equalling lower floret; awn dorsal, keeled, twisted; ovary hairy above; fruit crested and furrowed.

497. Arrhenatherum. - Florets 2; upper perfect, lower staminate only; rachilla produced beyond flowering glumes; lower with awn long, twisted from below middle; upper with short straight awn near tip.

498. Cynodon. - Spikelets fingered in com -pound, spreading spike; in 1-2 series; rachis flat, laterally compressed; glumes equal, spreading, awnless.

499. Sieglingia (Triodia). - Spikelets 2- (or more) flowered; rachilla not bearded; glumes unequal, acute, as long as outer palea; flowering glume deeply concave, notched, with teeth; fruit free.

500. Phragmites (Arundo). - Spikelets with 2 or more perfect flowers; rachilla bearded, with long silky hairs; fruit not attached to palea.

501. Sesleria. - Florets without awn; spikelets in panicled spike, with ciliate bract below, overlapping; lower palea keeled, membranous; with 3-5 points.

502. Cynosurus. - Spikelets in spike or head; bract below pectinate; glumes subequal, keeled; lower palea with bristle; fruit enclosed in palea.

503. Koeleria. - Spikelets in sub-cylindrical interrupted spike, 2- (or more) flowered, flattened; flowering glume membranous; fruit not enclosed in palea.

504. Molinia. - Panicle contracted, conical, round in section, glumes shorter than florets, without lateral ribs; florets 1-2; palea hardening in fruit.

505. Catabrosa. - Panicle spreading, loose, branches whorled; glumes unequal, I-veined; florets 2, distant.

506. Melica. - Florets 1-2 perfect, rounded on back, and 1 or more imperfect; glumes equal, veined, nearly as long as spikelet; palea hardening in fruit.

507. Dactylis. - Panicle secund; spikelets crowded, few; glumes unequal; lower keeled; lower palea flattened; fruit free.

508. Desmazeria. - Spikelets 2-rowed, in spike, rigid; glumes 8-12; blunt, blunt-pointed, with faint nerves.

509. Briza. - Spikelets in panicle, drooping; glumes broad, blunt, membranous, boat-shaped, saccate; fruit attached to palea.

510. Poa. - Spikelets in panicle; glumes acute, unequal; flowering glumes flat, keeled, awnless, tips nerved.

511. Glyceria. - Spikelets with many flowers; glumes unequal, membranous; flowering glumes convex, tip blunt, nerveless; lower palea with 7-10 ribs.

512. Festuca. - Panicle one-sided; flowering glumes convex, tip nerved, acute, or awned; ovary smooth; lower palea rounded or with ex-current vein.

513. Bromus. - Spikelets in panicle; florets many; lower glumes I-veined, upper 3-5-veined; glume shorter than lower floret; awn straight.

514. Brachypodium. Spikelets solitary, nearly sessile; glumes unequal, opposite; edges to rachis; upper palea coarsely fringed on ribs; ovary-tip villous.

515. Lolium. - Spikelets solitary; florets many; sides to rachis; glume I, or inner smaller.

516. Agropyrum (Triticum). - Spikelets solitary, edge to rachis; glumes equal, opposite; lower palea ciliate on ribs.

517. Lepturus. - Spikelets solitary, alternate on rachis; glumes 1-2; both on same side of rachis, cartilaginous; empty glumes 1-3.

518. Nardus. - Spikelets solitary; spike 2-rowed, one-sided; style long; glumes o.

519. Hordeum. - Spikelets 1-flowered, in 3's; paleae with long awns; glumes 2, with long bristles.

520. Elymus. - Spikelets 2-3, florets 2-7; glumes 2, on same side of spikelet; no awns or bristles.