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and which have been regarded as representing very reduced sepals. Each flower is protected by two much larger structures, the inner, usually two-keeled, palea and the round, single-keeled, lemma. The lemma and palea fit closely together over the flower and are only separated for a short time when the lodicules swell up temporarily, pressing them apart, and allowing the styles and stamens to protrude and wind-pollination to take place.
Each true flower plus its lemma and palea is known as a “floret” and the spikelet consists of from one to about twenty florets. At its base there are two (occasionally one or none) protective structures, the glumes. Both the lemmas and the glumes may be furnished with bristles (awns), which are useful features for identification.
The following key will enable the more important species to be identified in the flowering stage.
KEY FOR IDENTIFICATION OF COMMON GRASSES WHEN IN FLOWER
| 1 | Inflorescence a spike; spikelets not stalked. | 2 |
| Inflorescence a raceme. One very shortly-stalked,many-flowered spikelet at each node. | Brachypodium spp. | |
| Inflorescence a panicle (spikelets on long or shortbranched stalks). | 7 | |
| 2 | Spike branched. | Spartina spp. |
| Spike not branched. | 3 | |
| 3 | One spikelet at each node. | 4 |
| Two spikelets at each node. Spike large, spikeletsseveral-flowered. | Elymus arenarius | |
| Three spikelets at each node. Spikelets one-flowered, central one only fertile. | Hordeum spp. | |
| 4 | Spike one-sided; spikelets one-flowered. | Nardus stricta |
| Spike not one-sided; spikelets several-flowered. | 5 | |
| 5 | Spikelet placed edgewise; 1 glume only. | 6 |
| Spikelet placed sideways on; 2 glumes. | Agropyron repens | |
| (Wheat 3 or more large florets and broad glumes,lemmas usually awnless, and Rye with two large floretsand narrow glumes, lemmas always awned, come here) | ||
| 6 | Lemmas awnless. | Lolium perenne |
| Lemmas awned. | Lolium multiflorum | |
| 7 | Spikelets usually many-flowered (4 or more);glumes short, not hiding florets. | 8 |
| Spikelets few-flowered (2–5 usually); glumes long,concealing at least the lower florets. | 19 | |
| Spikelets one-flowered; glumes long, concealingfloret. | 23 | |
| 8 | Panicle branches mainly spreading. | 9 |
| Panicle branches very short, not spreading, so thatinflorescence looks more like spike. Sterileskeleton spikelets present as well as fertile. | Cynosurus cristatus | |
| 9 | Lemmas with awn on back. | 10 |
| Lemmas awnless or with awn on tip. | 11 | |
| 10 | Lemmas rounded, spikelet oval. | Bromus mollis & related species |
| Lemmas keeled, spikelet triangular. | Bromus sterilis & related species | |
| 11 | Lemmas with rounded back. | 12 |
| Lemmas keeled on back. | 16 | |
| 12 | Lemmas very blunt. | 13 |
| Lemmas bluntly or sharply pointed or shortlyawned. | 14 | |
| 13 | Spikelets long, cylindrical. | Glyceria fluitans |
| Spikelets short, rounded-triangular. | Briza media | |
| 14 | Panicle purple, usually long and slender, stigmaand anthers dark purple. | Molinia caerulea |
| Panicle green, becoming brown or yellowish.Stigma and anthers pale. | 15 | |
| 15 | Panicle and florets small. | Festuca ovina & F. rubra |
| Panicle and florets larger, two branches at mostnodes, with 1 or 2 spikelets on smaller branch,lemmas bluntly pointed. | Festuea pratensis | |
| Panicle very large, 3 or more spikelets on smallerbranch, lemmas with awn-point. | Festuca arundinacea | |
| 16 | Lemmas straight, bluntly pointed. | 17 |
| Lemmas curved, with awn point, panicle largewith dense clumps of spikelets. | Dactylis glomerata | |
| 17 | Panicle small, no “web.” | Poa annua |
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Panicle larger, “web” of cottony hairs at base oflemma.
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