Master Key

Master Key and Generic Index

Use this key as your fist step in identification. It will send you to a genus, or to individual species.

First of all, is the plant a grass?

Grasses are members of the Poaceae family. They are often confused with Sedges (Cyperaceae), Rushes (Juncaceae), and sometimes other plants. Many plants that are not grasses have "grass" in their names: Mondo-Grass, Yellow-Eyed-Grass, Sawgrass, Stargrass, and many more.

Grasses have:

Round stems (vs. usually triangular in sedges)
Leaves usually in 2 rows as seen from the end of the plant (vs. usually in 3 rows in sedges)
Leaves all along the stem (vs. often restricted to the top and/or bottom in sedges)
Hollow stems (there are exceptions)
Ligules on the leaf blades (again, there are some exceptions)
Tiny flowers with no apparent sepals or petals (vs. rushes) enclosed in a lemma and palea

Note: Use the to find definitions and pictures of unfamiliar words and terms

If your plant is not a true grass, try our key to Sedges and Rushes.

If a true grass, continue downward on the present page:

Select the descriptive category that best fits your grass. There are 11 categories. The categories have sub-categories which may be further divided. Categories overlap and several grasses appear under multiple categories.

Category 1. Plants Huge, > 8' tall

Try first: Pennisetum purpureum, Phragmites, Saccharum giganteum

1-A. Inflorescence resembles a bristly hot dog

Uncommon (Strongly auriculate leaves. Hymenachne can be > 8' tall but usually is much smaller, sometimes just 2' tall. Found in water.)

Very common ("Elephant Grass" is an abundant weed in agricultural areas forming junglelike stands. Has orange-brown bristly foxtail inflorescence rising 12' above the ground. Leaf blades with white midrib. Inflorescence resembling a bristly tan hotdog. If you are attempting to identify a huge roadside grass in South Florida, this is the most likely grass.)

Very rare (Large grass of swampy places. Bristly foxtail inflorescence.)

1-B. Spikelets with awns

(Leaves notably long, narrow, saw-toothed, and white-striped. Spikes look like head of wheat with long kinked awns)

Rare (Spikelets feathery-pubescent, with a curled awn 3 mm long. Rare in our area. Similar to Phragmites which is abundant. But unlike Phragmites which has long-attenuate straight spikelet tips, Neyraudia has bent awns, glabrous internodes, and pubescent lemmas.)

Very common (Inflorescence with many long slender droopy axes, resembling a wimpy upside-down broom. Spikelets feathery-pubescent, 8-15 mm long, with long-tapered tip consisting of a short semi-awn. Ligule area bare except for the ligule itself.)

Very common (Inflorescence maturing into a white-feathery plume. Sessile spikelets 4.2-6 mm long, with straight awns to 24 mm long. Ligule area woolly)

Unusual (Large showy grass of open pine woods and low moist areas. Inflorescence notably one-sided. Ligule bi-lobed and 4 mm long. Spikelets woolly and long-awned.)

1-C. Spikelets without bristles or awns

Rare in our area (Huge grass with strongly developed auricles. Leaf bases/auricles white or tan. Try Phragmites which is similar but does not have auricles)

Very common (Inflorescence with many long slender droopy axes, resembling a wimpy upside-down broom. Spikelets feathery-pubescent, 8-15 mm long, with long-tapered straight tip constituting a short semi-awn. Often very large, a likely candidate if you are identifying a huge roadside ditch cane with branched inflorescence.)

(Inflorescence pencil-like. Sheath hirsute with irritating papilla-based hairs. Leaf with a central stripe resembling that of Pennisetum purpureum. If you think you have Rottboellia, don't grab it---ouch!)

(Sugarcane. Spikelets feathery-pubescent. Sessile spikelets 3-5 mm long, not awned. Rare outside of cultivation)

Very common (Ranges in size from 2' to 12'. Fertile lemma white-rugose. Inflorescence with the main branches whorled. This huge weed is everywhere)

Category 2. Spikelets With Awns

(Awns are threadlike or needlelike extensions)

Photo: Sorghastrum secundum showing awns

2-A. Awns 3 per spikelet

Very common (Awns uniquely 3[4] per spikelet)

2-B. Awns < 18 mm long

2-B-i Inflorescence an open panicle (the main branches with well developed secondary branches)

Largest leaf blades > 15 mm wide

Very rare (Awns very short, 5 mm. Broad-leaved grasses of deep shaded hammocks.)

Rare (Spikelets feathery-pubescent, with a curled awn 3 mm long. Rare in our area. Similar to Phragmites. which is abundant. But unlike Phragmites which has long-attenuate straight spikelet tips, Neyraudia has bent awns, glabrous internodes, and pubescent lemmas.)

Very common (Huge common roadside-ditch weed 8'-12' tall. Scarcely awned. Inflorescence with long drooping branches)

Uncommon (Massive, thick-stemmed grasses to 7' tall, having leaves > 1" wide and large flame-shaped or droopy panicles. Spikelets with a bent, twisted awn 1.5 cm long.)

Largest leaf blades < 15 mm wide

(Some species with awns of variable lengths 0-30 mm. Coarse grasses in wet habitats. Inflorescences panicles with the main branches densely covered with spikelets or short, condensed side branches. Spikelets often with papillose-based hairs. Identification aid: The species in our area have no ligules, a very unusual trait.)

Very rare (Awns very short, 5 mm. Broad-leaved grasses which resemble young bamboo. Found in deep shaded hammocks.)

(Plants fuzzy-pubescent and fragrant. Panicles purplish. Lemmas notched with awn to10 mm long seated in notch)

Abundant (Fluffy feathery spikelets reddish-pinkish. Abundant weed on dry sandy soils)

(Much cultivated. Wispy pink panicles in autumn. Leaf blades extremely narrow, 2-4 mm)

2-B-ii. Inflorescence variable (raceme, spike, broom, etc. but not with the main branches having well developed secondary branches)

Very common (Ultimate inflorescence axes paired, white fuzzy-hairy. Awns usually < 16 mm long. Dichanthium may be similar but < 1 m tall, the inflorescences clustered near the stem tip and the awns often exceeding 16 mm.)

(Look for the unique pit on the glume. Dichanthium similar but no pit on glume.)

(Awns 0-30 mm or absent. Coarse grasses found in wet habitats. Inflorescences panicles with the main branches densely covered with spikelets or short, condensed side branches. Spikelets often have papillose-based hairs. The species in our area distinctively have no ligules.)

(Inflorescence branches straight. Spikelets laterally compressed. Awn 1 mm long, seated in a notch in the lemma. Ligule to 8 mm long, lacerate. Wet habitats.)

Rare (Spikelets sessile, scattered uncrowded along a vertical spike, often awned. Rare away from over-seeded turf)

(Shade-loving, ground-hugging grasses 8" tall. Awned spikelets in widely scattered clusters or on short widely separated side-branches)

Very common (Awns 1 mm -15 mm. Inflorescence axes zig-zag. Feathery-fuzzy when mature, differing from Andropogon by NOT having the ultimate inflorescence branches paired)

2-C. Awns > 18 mm long

(Spikelets long, to 1.5 cm on long pedicels, awns to 15 cm. See also Heteropogon)

(Awns often > 18 mm long; grass similar to Bothriochloa but with no pit in glume; and similar to some Andropogons but usually smaller-statured, with rames confined to the top, and with longer awns)

(Awns 0-30 mm or absent. Coarse grasses in wet habitats. Inflorescences panicles with the main branches densely covered with spikelets or with short, condensed side branches. Spikelets often having papillose-based hairs. The species in our area have no ligules.)

(Spikelets and awns almost as long as in Chrysopogon but differing by having the 10-15 cm awns twisted together into one apparent super-awn, and the spikelets sessile rather than pedicellate)

(Large weed with narrow sawtooth leaf blades having a white central stripe. Awns 2-3 cm. Flowering heads resemble a head of wheat)

(Fall-blooming with the inflorescence 1-sided like the teeth on a comb, this rising from the base on a bare wand 6' tall. See photo above)

(Saccharum giganteum is a tall [8'] grass of wet sites. Wooly in the ligule region. Inflorescence on a long bare wand 7' tall. Spikelets with awns to 24 mm long)

Category 3. Mature Inflorescence Feathery, Fuzzy, Silky, or Cottony

3-A. Grass > 8' tall

Rare (huge grass > 8' tall with strongly developed leaf-base auricles. Leaf bases/auricles white or tan.)

Very common (Inflorescence shaped like a bristly hot dog; see also Setaria. In Setaria the bristles below the spikelet which falls free of the bristles. The lemma is hard and rough-surfaced. In Pennisetum the spikelets are surrounded by bristles and fall with them. The lemma is soft)

Very common (Huge ditch grass > 8' tall with droopy inflorescence branches)

Very common (Saccharum giganteum is a tall [8'] grass which likes wet sites. Wooly in the ligule region. Inflorescence on a long bare wand. Spikelets with awns to 24 mm long)

Very common (plants 1'-12' tall - depending on species. The shorter species common, the tall species rare. Inflorescence shaped like a bristly hot dog. See also Pennisetum. In Setaria the bristles are below the spikelet which falls free of the bristles. The lemma is hard and rough-surfaced. In Pennisetum the spikelets are surrounded by bristles and fall with them. The lemma soft)

3-B. Grass < 8' tall

Very common (Ultimate inflorescence branches paired like feathery white bunny ears)

(Ultimate feathery units clustered, the glume with a conspicuous pit)

(Inflorescence roughly the size and shape of a fuzzy reddish pencil)

(Inflorescences bleached-white and cottony)

Very common (Fluffy spikelets are reddish-pinkish. Weed on dry sandy soils)

Very common (Ultimate feathery inflorescence units zig-zag, not paired and are feathery when mature. Spikelets awned)

Very common (Plants 1'-12' tall depending on species. Inflorescence shaped like a bristly hot dog. See also Pennisetum. In Setaria the bristles are below the spikelet which falls free of the bristles. The lemma is hard and rough-surfaced. In Pennisetum the spikelets are surrounded by bristles and fall with them. The lemma is soft)

Category 4. Inflorescence Shaped Like a Hot Dog

4-A. Hot dog is bristly (like a brush, or a porcupine)

Very common (Sand spurs with nasty burrs)

Common (Spikelets resembling a purplish, fuzzy pencil more than a hot dog. Common in open sandy disturbed places)

Very common (Inflorescence resembling a bristly hot dog. See also Setaria. In Setaria the bristles are below the spikelets which fall free of the bristles. The lemma is hard and rough-surfaced. In Pennisetum the spikelets are surrounded by bristles and fall with them. The lemma is soft.)

(with bristles beneath the spikelets. See also Pennisetum. In Setaria the bristles are below the spikelets which fall free of the bristles. The lemma is hard and rough-surfaced. In Pennisetum the spikelets are surrounded by bristles and fall with them. The lemma is soft)

4-B. Hot dog is not bristly (may be rough, bumpy, fuzzy, or silky but not bristly or prickly)

Common (Spikelets resembling a purplish, fuzzy pencil more than a hot dog. Common in open sandy disturbed places.)

Rare (Broad leaves, strongly auriculate. The basal lobes reaching around the stem. In wet places.)

Occasional (Inflorescence snow-white fluffy)

(Grass 2'-5' tall. In wet places. Inflorescence may emerge and remain for weeks as a tightly congested very irregularly shaped "hotdog," or the branches may expand. Spikelets usually reddish. The fertile lemma has hairs at the tip which are best seen with magnification.)

(Inflorescence sparse and extremely narrow, < 1 cm wide, not a very good hot dog. In wet places)

Very common (Spikelets strongly lopsided. In wet habitats)

(Inflorescence not really much like a hot dog, but included here just in case you disagree. Spikelets tightly congested, 2 mm long. The lower glume is half as long and has 1 vein. Spikelets with no hairs or awns)

(Beach species)

(Turf species. Plant 4" tall. Inflorescence a single spikelet 1/2" tall)

Category 5. Inflorescence Shaped Like a Pencil or a Narrow Wand (< 2 cm diameter)

5-A. Grass > 1 m tall

5-A-i. Inflorescence with the spikelets cylindrical or slightly flattened, in a single row, looking a little like a stack of cans

(4' tall. In wet habitat. Lower glume usually with small to large wrinkles and irregularities)

Rare (4' tall and fragrant. Unbranched vertical pencil-sized spikes white-fuzzy when mature)

(4' tall, resembling Coelorachis but the pencil is flattened)

(Weed. Variable size 2'-10'. Leaf blades with a central white stripe - in large specimens blade may exceed 1" wide. Sheath with irritating papilla-based hairs)

Very common (Pencil-like only before expansion. Then mature inflorescence is fuzzy and zig-zagged. Spikelets with awns 1-15 mm long)

5-A-ii. Inflorescence narrow and only vaguely pencil-shaped due to the side-branches being upright and appressed to the main axis.

(Inflorescence sparse, irregular, and extremely narrow - a panicle with upright branches, < 1/2" wide. Leaves flat. In wet places)

(Leaf blades terete [resembling knitting needles]. Spikelet a narrow wand)

Very common (1'-4' depending on which species. Spikelets distinctively lopsided. Wet habitats)

5-B. Grass < 1 m tall

5-B-i. Grass < 20 cm tall

(grass 1' tall. Spikelets conspicuously reddish fuzzy)

(Centipede Grass---a turf species. 8" tall)

(turf grasses 4" tall. Sometimes escaped near the sea. Inflorescence with just 1 spikelet which is 1 cm long)

5-B-ii. Grass > 20 cm tall

Very rare (Spikelets sessile, scattered uncrowded along a vertical spike, and often awned)

(Leaf blades terete [resembling knitting needles]. Spikelet a narrow wand)

Very common (1'-4' depending on which species. Spikelets lopsided)

Very common (Inflorescence pencil-like only before expansion. Mature inflorescence is fuzzy and zig-zagged. Spikelets with awns 1-15 mm long)

Category 6. Inflorescence Shaped Like a Flame

or a Horse's Tail

(As some panicles in Category 9 might be regarded as flame-shaped, they are included here)

(Awns 3 per spikelet. Hundreds of them massed together create a flame-shaped tangle)

(Salt grass, a beach species. Has numerous florets per spikelet)

Very common (depending on the species, inflorescence may be flame shaped. Sporobolus species have glumes with single veins. When rolled between two palms the spikelets tend to drop their "seeds")

(turf species 4" tall. The single-spikelet inflorescence 1/2" tall)

Category 7. Inflorescence Shaped Like the Letter Y(and sometimes with extra arms)

7-A. Spikelets round, disk shaped or coin-shaped

(Thin delicate Y. Spikelets with long hairs. Spikelets dot-shaped. Similar to Digitaria longiflora which differs by having elongate spikelets)

(Bahia Grass, a turf species. Spikelets not paired)

7-B. Spikelets elongate, not circular in outline

(May have extra branch(es) below the Y. Spikelets solitary with no lower glume)

(Thin Y, resembles Paspalum conjugatum but spikelets elongate, not round and dot-shaped)

(Goosegrass, a common weed. Usually with extra branch(es) below the Y. Spikelets with numerous florets apparent)

(Plants creeping and semi-succulent. Inflorescence branches forming a Y. Spikelets boat-shaped. Found in salty places)

(Looks much like Paspalum vaginatum but found in freshwater. Extremely stoloniferous, with the stolon snaking several feet across moist sand. Spikelets boat-shaped)

Category 8. Inflorescence a Raceme

A raceme is an inflorescence with a central stem and simple branches attached to it, like the arms of a stick man. Some grasses which are technically a panicle (having branches on the branches) are included in this category if the secondary branching is slight and the inflorescence is an APPARENT raceme. If the secondary branching is well developed and appressed to the primary branches, grasses are listed in both Category 8 (raceme) and Category 9 (panicle).

8-A. Awn present (may be as short as 1 mm)

8-A-i Grass usually > 20 cm tall

(Some species with awns of variable lengths 0-30 mm, or absent. Coarse grasses in wet habitats. Panicles with the main branches densely covered with spikelets or short, condensed side branches. Spikelets often with papilla-based hairs. Identification aid: The species in our area have no ligules, a very unusual trait.)

(Leaves lanceolate. Inflorescence axes long, thin and straight. Lemmas notched with awn 4-6 mm. Rare)

(Inflorescence branches long and thin. Lemmas notched with tiny awn. See also Gymnopogon)

8-A-ii. Grass usually < 20 cm tall

(Shade-loving, ground-hugging grasses 8" tall with the awned spikelets in scattered clusters or on short widely separated side-branches. In moist shaded hammocks)

(Short-sprawling, sand-dwelling scrub species. Inflorescences purplish, the lemma notched)

8-B. Awn absent

8-B-i. Grass < 1 m tall

(Leaves slightly blue, having white pinstripes along the margins. Inflorescence with few spikelets, paniculate or racemose. Spikelets sparse, 6-9 mm long. Very common rhizomatous grass of low wet places, sometimes filling moist meadows with a "lawn")

(Inflorescence usually Y-shaped but may have extra branches below the Y. Spikelets single, with no lower glume, elongate)

(Usually with inflorescence branches radiating like spokes but some species with racemose inflorescences. Plants with large ligule resembling a miniature fingernail. Inflorescence branches often flattened and with a dark green line flanked by light green lines. Lower glume missing or very small, spikelets usually in pairs and often pubescent)

(Beach species. Numerous florets per spikelet)

(Some species with awns of variable lengths 0-30 mm, or absent. Coarse grasses in wet habitats. Inflorescences panicles with the main branches densely covered with spikelets or short condensed side branches, the spikelets often with papillose-based hairs. The species in our area have no ligules, a very unusual trait.)

Abundant (Most of the inflorescence branches radiating spokelike from one point, and usually with one extra branch attached below the others. Spikelets laterally compressed with numerous florets apparent. Abundant weed)

(Spikelets look like little round clams with one shell being the upper glume and the other shell being the lower lemma)

(Short-sprawling, sand-dwelling scrub species, inflorescences purplish, the lemma notched)

(Lower glume oriented toward the rachis. Wrinkled or bumpy "rugose" fertile lemmas)

8-B-ii Grass > 1 m tall

(Usually with inflorescence branches radiating like spokes but some species racemose. |Plants with ligule resembling a miniature fingernail. Inflorescence branches often flattened and with a dark green line flanked by light green lines. Lower glume missing or very small. Spikelets usually in pairs and often pubescent)

(Some species with awns of variable lengths 0-30 mm, or absent. Coarse grasses in wet habitats. Inflorescences panicles with the main branches densely covered with spikelets or short, condensed side branches, the spikelets often with papillose-based hairs. Identification aid: The species in our area have no ligules, a very unusual trait)

(Lower glume formed into a cup or bead at the base of the spikelet. Inflorescence axes conspicuously pubescent in E. michauxii)

(Spikelets look like little round clams with one shell being the upper glume and the other shell being the lower lemma)

(Upper lemmas and paleas wrinkled or "rugose")

(Gamma Grass, Fakahatchee Grass. "Fingers" break into segments)

(Lower glume oriented toward the rachis. Wrinkled or bumpy "rugose" fertile lemmas)

Category 9. Inflorescence a Panicle

A panicle is a bushy, multi-branched inflorescence with branches that are branched.

9-A. Spikelets with > 2 florets

(Spikelets with numerous overlapping lemmas from numerous florets, looking like a rattlesnake tail)

(Panicles purple and droopy. Lemmas notched with a tiny tooth in the notch)

(Beach species with huge, flat spikelets)

9-B. Spikelets with 1(2) florets

9-B-i. Spikelets awned, and/or pink, and/or feathery-fuzzy

(Plants sticky-pubescent and fragrant. Panicles purplish. Lemmas notched with awn to 10 mm long seated in notch)

Abundant (Fluffy feathery reddish-pink spikelets. Abundant weed on dry sandy soils)

(Much cultivated. Wispy pink panicles. Leaf blades extremely narrow: 2-4 mm)

9-B-ii. Spikelets not awned, not pink (Leersia may have a light violet flush), and not feathery-fuzzy (may have minute pubescence)

Spikelets < 4 mm long

(Very similar to Panicum and in some classifications included in Panicum. Inflorescence is an open panicle, but the inflorescence usually (with exceptions) located among the leaves or held immediately above them. Plants tending to form rosettes year-round or at least seasonally)

(Large genus - far more species with panicles than with apparent racemes. Look for spikelets where both glumes are present, both with at least 3 veins, and only 1 floret apparent. [There is a second, reduced, inconspicuous floret.] Lower glume oriented away from the axis [vs. Urochloa] and the fertile lemma usually smooth or nearly so [vs. Urochloa]. Steinchisma [often included in Panicum and keyed with Panicum here] has 1 or 2 hard thickened palea[s] )

(Spikelets 4 mm in S. striata, smaller in S. indica. Panicle tightly congested and hot dog shaped. Spikelets strongly lopsided)

(See Panicum)

(Resembling Panicum but lower glume adjacent to the stem. Fertile lemma wrinkled)

(Panicles usually narrow. Spikelets hairless, the glumes characteristically single-veined. When rubbed between two hands the spikelets drop their "seeds")

Spikelets 4 mm or longer

(Beach species with a narrow congested panicle. Has numerous florets per spikelet)

Rare (Shade-dwelling, limp-stemmed, with usually broad, auriculate leaf blades. Spikelets 3.5-4.5 mm long, widely spaced, obovate)

(Spikelets 5 mm long, flushed with light violet, having hispid margins. Anthers 6. Inflorescence axes zigzag. Found in wet places)

(Panicle tightly congested and hot dog shaped. Spikelets strongly lopsided)

Very rare (Spikelets with 1-veined glumes, hairless, 4 mm long. Rare in our area, if present at all)

(Coarse weedy grasses with spikelets 5-6 mm long. Leaves distinctively soft-fuzzy. Rare)

Category 10. Finger Grasses. Inflorescence Branches Radiating Like Spokes From a Single Point or Resembling Fingers on a Hand

(Inflorescence Y-shaped but may have extra fingers below the Y. Spikelets with no lower glume, solitary, elongate)

(Look for a unique sunken pit on the glume)

(Bermudagrass, a lawn species. Leaf blades 1 mm wide)

Abundant (Fingers with spikelets on one side, either borne horizontally or drooping. Spikelets two-ranked and containing short bristly awns. Very abundant weed)

(Lower glume missing or very small. Spikelets usually in pairs, often conspicuously pubescent. See Digitaria bicornis, D. ciliaris, D. eriantha)

Common (Goosegrass. A common weed. Most of the branches radiating from one point, with an extra branch inserted below the others. Spikelets with numerous florets apparent)

Abundant (Fingers with spikelets strongly 1-sided, upright. Spikelets with small awns. Abundant weeds)

Category 11. Special Cases, Miscellaneous

11-A. On the Beach

Very common (Sandspurs with painful burrs)

(Narrow panicle)

(Large, coarse grass with an upright, narrow panicle)

(Inflorescence branches forming a Y)

(Wiry thin upright leaves)

(Inflorescence a fuzzy hot dog)

(Sea Oats. Large [6'] seaside grass with showy flat spikelets)

(Escaped lawn grass, 4" tall)

10-B. With painful spiny burrs...Sandspurs

Very common (Sandspurs with painful burrs)

10-C. Inflorescence curled like a letter C, or into a loop

(Inflorescence looks like a roller-coaster ride at Orlando, the spike one-sided resembling a curled toothbrush)