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 name: 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 constituting 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 wooly)

Unusual (Large showy grass of open pine woods and low moist areas. Inflorescence notably one-sided. Ligule bi-lobed and 4 mm long. Spikelets wooly 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. Inflorescene 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. To 10 mm long seat in notch)

Abundant (Fluffy feathery spikelets which are 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)

(Look for the unique pit on the 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 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 Bushy,

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 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. Very common 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 a 15X loupe.)

(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 Cateegory 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 umerous 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(but sometimes with extra arms)

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

(Thin delicate Y. Spikelets with long hair. Spikelets dot-shape. 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