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Tribe Eragrosteae
Key to Genus Eragrostis Linneaus
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Grasses of the genus, Eragrostis (commonly called lovegrasses), are small to medium clumping grasses that are relatively easy to recognize in the field if you closely examine the spikelets. Each spikelet comprises several to many florets, the latter arranged in a flattened, oval or much elongated "oval" (linear) with the florets tightly imbricate (packed close together, alternating along the rachis; think articulated fish charm). At the base of each spikelet are two, more or less similar, glumes. Each spikelet is attached to a thin pedicel. Species of Poa, Bromus, and a few other genera might be confused with Eragrostis spp., having a somewhat similar arrangement of the florets.
Twentyfive (25) or 26 species of Eragrostis are reported to be present in Hawai‘i (Clayton & Snow, 2010; Imada, 2019; Faccenda, 2022); most are not commonly encountered. Ten (10) of the Eragrostis species here are native and all but one, endemic (unique to Hawai‘). Thus, this genus is an important component of the native flora of the Hawaiian Islands. However, the two most common species in disturbed lowland sites are non-natives: Carolina lovegrass (E. pectinacea, extremely ubiquitous) and Japanese lovegrass (E. amabilis). Six species are reported from Guam (Raulerson, 2006), all native with the exception of E. amabilis. In Hawai‘i, E. variabilis (kāwelu) is a native typically encountered in dry, wind-swept areas.
The key below is a work in progress and the large number of species (32 across the Pacific islands) would indicate that identification to species can be difficult. Clayton & Snow include the notation: "many species intergrade, at least slightly". Faccenda (undated) concludes that "In Hawai‘i, identification of Eragrostis is, by far, the most difficult of all the genera of grasses".
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Figure 20A. Inflorescence of sheepgrass
(Eragrostis brownei), here showing nine spikelets
typical in form of most Eragrostis species. Note
spreading, subequal glumes at base of each spikelet;
the glumes are shorter than the first lemma (essentially first floret).
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[GENUS ERAGROSTIS]
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90a
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( 93) |
Paniculate inflorescence open, the branches spreading .. .
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[91] |
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90b
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Paniculate inflorescence narrow, spike-like, branches pressed against the culm or at least relatively short and ascending, thus forming a column of (usually) densely-packed spikelets
.. .
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[98]
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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91a
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(90) |
Spikelets small, less than 1/8 in (3 mm) across and 1/3 in (5 - 8 mm) long .. .
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[92] |
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91b
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Individual spikelets larger, at least 1/8 in (3 mm) across and 1/4 in (10 mm) long or longer .. .
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[94]
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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92a
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(91) |
Spikelets 4 to 6 flowered, only slightly longer than wide (~1/16 in or 2 mm long). { Small grass of dry areas and disturbed sites. Japanese lovegrass. [HAW - NAT] [GUM - NAT]Eragrostis amabilis (L.) Wight & Arnott
Consider that Sporobolus tenuissimus somewhat resembles E. amabilis in habit..
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92b
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Spikelets 5 to 18 flowered, at least twice as long (1/8 to 1/3 in [3 to 8 mm]) as wide, although some spikelets with fewer flowers may be only slightly longer than wide .. .
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[93]
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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93a
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(92) |
 Leaf blade margins smooth. Ligule ciliate. { Small grass, very common in disturbed sites. Carolina lovegrass. [HAW - NAT]Eragrostis pectinacea (Michx.) Nees
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93b
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Some nodes purple-brown in color. Leaves densely hairy at the collar and hairy down the sheath (?or not). Ligule a dense band of short hairs. Leaf blade margin with a row of conspicuous tubercles (glands), these giving a musty odor when fresh. { Small grass, in dry, usually disturbed sites. Stinkgrass [HAW - NAT]
Eragrostis cilianensis (All.) Link
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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94a
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(91) |
Some or all mature spikelets with more than 30 florets, linear in shape. { Medium size grass, culms usually erect
.. .
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[99]
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94b
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Mature spikelets all with fewer than 30 florets, typically 10 to 15 more or less, oval or elongated oval in shape. { Usually small grass, culm typically prostrate or decumbant, sometimes erect .. .
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[95] |
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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95a
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(94) |
Glumes aristate: having a small prolonged tip or short awn. (Fig. 17A). Sheepgrass [HAW - NAT] [GUM - NAT]Eragrostis brownei (Kunth) Nees ex Steud.
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95b
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Glumes obtuse or acuminate (coming to a sharp-angled tip), but not aristate
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[96]
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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98a
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(90) |
Spikelets hairy, margins of lemmas fringed with long cilia, keels scabrous; glumes lacking hairs, although keels scabrous with curved "hairs". Glumes subequal, shorter than first lemma. Spikelets 3-4 mm long. {Small, annual, clumping grass in dry areas. [HAW - NAT] [GUM - NAT]Eragrostis ciliaris (L.) R. Br. Kunth
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98b
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Spikelets not hairy.
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[99]
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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99a
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(98) |
Inflorescence very narrow, under 1 cm across. First glume longer than first floret; second glume as long or longer than second floret.
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[100]
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99a
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(98) |
Inflorescence more or less spikelike, tending to columnar in shape, but greater than 1 cm across.
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[101]
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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100a
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(98) |
Leaves primarily basal, apex slender to a narrow point. Inflorescence 5-15 cm (2-6 in) long; spikelets 6-8 flowered, somewhat interupted along axis. { small perennial on Maui nui and Hawai‘i. Kalamālō [HAW - END]Eragrostis monticola (Gaud.) Hillebr.
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100b
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Leaves distributed up the culm (cauline). Inflorescence 15-30 cm (6-12 in) long; spikelets 4-10 flowered, dense on culm. { small perennial on Lānai, Maui and Hawai‘i. [HAW - END]Eragrostis leptophylla Hitchc.
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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101a
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(99) |
Leaves coarse, margins parallel, almost strap-like. Ligule a short, ciliate membrane. Paniculate inflorescence with branches stiffly ascending or slightly speading. Spikelets (2)3-12(-14) flowered. Glumes subequal, shorter than first floret, some glumes with a short arista (narrow scabrous extension at tip). Lemma with 3 nerves. { Dense tufted perennial, 2-3 ft in height. Typically found on wind-blown sites, dry ridges, exposed dunes (see also couplet [91]). Kāwelu [HAW - END]Eragrostis variabilis (Gaud.) Steud.
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101b
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Inflorescence with branches stiffly ascending, from 0 to 10 cm long. Ligule a ciliate ridge. Spikelets 8-15 flowered, imbricate. First glume longer than first floret, second glume slightly longer. { Loose tufted perennial, 3-4 ft in height. Typically found on dry, exposed sites, mostly above 4000 ft (1,220 m) elevation. [HAW - END] Eragrostis atropioides Hillebr.
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Species of Eragrostis reported to be in Hawai‘i or Guam and either not covered
in this key or included under a more recent name (= accepted name):
E. atrovirens (Deaf.) Trin. [GUM]
E. barrelieri Daveau [HAW]
E. curvula (Schrad.) Nees [HAW]
E. deflexa Hitch. [HAW]
E. dielsli Pilg. [HAW]
E. elongata (Willd.) J. Jacq. [HAW]
E. fosbergii Whitney [HAW]
E. grandis Hillbr. [HAW]
E. hosakai Degener (= E. leptostachya)
E. leptostachya (R. Br.) Steud. [HAW]
E. mauiensis Hitch. [HAW]
E. minor Host. [GUM]
E. parviflora (R. Br.) Trin. [HAW]
E. paupera Jedwabn. [HAW]
E. pilosa (L.) Beauv. [HAW] [GUM]
E. sessilispica Buckley [HAW]
E. superba Peyr. [HAW]
E. tenella (L.) Roem. & Schultes. (= E. amabilis)
E. tenuifolia (A. Rich.) Hochst. ex Steud. [HAW]
E. trichodes (Nutt.) Wood. [HAW]
E. trichophora Coss. & Durieu [HAW]
E. unioloides (Retz.) Nees ex Steud. [HAW]
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© 2012-24 AECOS, Inc. [ver. 240202]
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Genus Eragrostis ~ Page 20
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