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Calamagrostis expansa

(Munro ex Hillebr.) Hitchc. (1922)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Monocots Order: Poales Family: Poaceae Genus: Calamagrostis

reedgrass

Description

Key Characters:

Growth Form: Robust perennials, short–rhizomatous.

Stems: Culms erect or sometimes decumbent, 5–20 dm tall, 4–8 mm in diameter.

Roots:

Leaves: Leaves simple. Alternate. Blades flat to involute, firm, 15–20 cm long, 1–3 cm wide, the uppermost reduced. Apex indurate, hard–pointed. Upper surfaces scabrous and plicate; lower surfaces glabrous. Margins membranous, throat sparsely pubescent. Sheaths overlapping rather closely along the middle of the culm, minutely retrorse–scaberulous, ligule membranous to chartaceous, 3.5–4 mm long, puberulent, apex triangular to rounded, erose; blades flat to involute, firm, 15–20 cm long, 1–3 cm wide, the uppermost reduced. Stipules absent.

Flowers: Flowers in inflorescences paniculate, oblong, contracted, 15–30 cm long, densely scabrous, the branches ascending, loosely appressed to axis, devoid of spikelets on lower 1⁄2 of branch, rachilla 1.5–2 mm long, obscured by long whitish yellow silky hairs up to 1 cm long; glumes equal, pale, persistent, longer than floret, spreading, slightly recurved, ca. 7 mm long, scabrous on keel and otherwise scaberulous, apex acuminate, first glume 1–nerved, second glume 3–nerved, nerves green; lemma thin, chartaceous to membranous, 4–4.5 mm long, 5–nerved, nerves green, scabrous, callus thickened, hardened, densely silky pubescent the hairs 4–5 mm long, encircling floret, apex 4–toothed, the teeth slender, midnerve produced into an awn 7–10 mrn long; palea 2.5–3 mm long, 2–nerved, scabrous, acuminate. Ovary superior.

Fruit: Caryopsis pale brown; ovoid; 2–2.5 mm long; slightly grooved ventrally; apex apiculate.

Ploidy:

Habitat: Apparently rare in wet forest; open bogs; and bog margins.

Elevation Range: 950–2,290 m.

Historical Distribution

Uses and Culture

USES

Natural History

Statewide Status

Endemic

Island Status

O'ahu Unknown
Maui Endemic
Hawai'i Endemic

Dispersal Agents


Pollinators

Bibliography

Name Published In: Mem. Bernice Pauahi Bishop Mus. 8: 149 (1922)

Other References

Wagner et al. 1990:1509 (M); Herbst & Clayton 1998:21 (H); Peterson et al. 2022 (COMBNOV, Syn. C. expansa = Greeneochloa expansa, not followed [as taxonomy of C. hillebrandii still unclear, see Faccenda 2025b:113])

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Description Recorded By Record Number Island Source Date
1 Calamagrostis expansa Locality redacted. Contact Bishop Museum Botany Department for details At edge of open bog. Preserved_Specimen Herbst, D.R. 1330 Maui BISH 1968-11-28
2 Calamagrostis expansa W Maui, Puu Kukui Open bogs Preserved_Specimen Ewart III, G.R. 77 Maui BISH 1928-12-18
3 Calamagrostis expansa East Maui, Hana District, Hana Forest Reserve, Kipahulu, on ridge above N rim In open bog with Oreobolus, Styphelia, Viola, Vaccinium, and Deschampsia Preserved_Specimen Harrison, B. 478 Maui BISH 1973-09-23
4 Calamagrostis expansa Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Herbst, D.R. 478 Oahu BISH 1967-05-06
5 Calamagrostis expansa Locality redacted. Contact Bishop Museum Botany Department for details Preserved_Specimen Herbst, D.R. 3051 Maui BISH 1973-08-08
6 Calamagrostis expansa Honokahau Drainage Basin Preserved_Specimen Forbes, C.N. 371 Maui BISH 1917-09-25
7 Calamagrostis expansa East Maui, Manawainui Planeze near trail to USFWS Transect 18A from Kuiki Preserved_Specimen Welton, P. 2407 Maui BISH 2018-10-02
8 Calamagrostis expansa East Maui, Hana District, Hana Forest Reserve, near Wai Anapanapa On hillside with Railliardia, Vaccinium, Lysimachia, Dryopteris spp. and Sadleria. Preserved_Specimen Harrison, B. 485 Maui BISH 1973-09-23
9 Calamagrostis expansa East Maui, Hana District, Hana Forest Reserve, on ridge above N rim of Kipahulu In open bog with Oreobolus, Styphelia, Viola, Vaccinium, and Deschampsia Preserved_Specimen Harrison, B. 478 Maui BISH 1973-09-23
10 Calamagrostis expansa W Maui, Eke Trail Base of Eke Crater in bog turf. Preserved_Specimen Medeiros, A.C. 340 Maui BISH 1982-11-09
11 Calamagrostis expansa East Maui, Haleakala Ranch pipe line Edge of forest, on side of stream bed. Preserved_Specimen Munro, G.C. 748 Maui BISH 1927-11-26
12 Calamagrostis expansa Haleakala, Wai Anapanapa Bog below Wai`anapanapa Preserved_Specimen Forbes, C.N. 1231 Maui BISH 1919-08-23
13 Calamagrostis expansa S Kona District; Kohala Mts.; above Honokane Nui stream E of USGS trail 200 plants scattered in bog; clumping in sphagnum. Metrosideros-Cheirodendron montane wet forest & Metrosideros-Macherina montane bogs with Styphelia, Carex alligata, Calamagrostis expensa, Oreobolus furcatus, Dichanthelium cynodon, Stenogyne cranwelliae, Myrsine spp., Rhynchospora chinensis. Threats: Pigs, Juncus spp., Polygonum punctatum. Preserved_Specimen Leaves dark green. Wood, K.R. 4811 Hawaii BISH 1995-11-29
14 Calamagrostis expansa W Maui Mnts., Puu Kukui Growing in bogs Preserved_Specimen Higashino, P.K. 7618 Maui BISH 1976-01-05
15 Calamagrostis expansa east Maui, Hana District, Hana Forest Reserve, Kawaipapa drainage basin, 600 m north of Waihoi Valley. at margin of small bog. Vegetation: Metrosideros, Machaerina, Rhynchospora, Carex, Dubautia, Dicanthelium, Viola, Dicranopteris, Lobelia, Plantago, Schizaea, Leptecophylla, Scaevola, Lycopodium. Preserved_Specimen Rare grass; five clumps in this location along and below fence., with several others noted nearby. Oppenheimer, H.L. 81325 Maui BISH 2013-08-20
16 Calamagrostis expansa East Maui, Hana District, Haleakala, Hana Forest Reserve, Wai Anapanapa Bog below Wai`anapanapa Preserved_Specimen Forbes, C.N. 1231 Maui BISH 1919-08-23
17 Calamagrostis expansa East Maui, Haleakala Ranch pipe line Edge of forest, on side of stream bed Preserved_Specimen Munro, G.C. 748 Maui BISH 1927-11-26
18 Calamagrostis expansa Wai Anapanapa, Haleakala Kipahulu-Kuhiwa divide Thicket at tree line Preserved_Specimen Culms 2-5 in a clump St.John, H. 21036 Maui BISH 1945-08-16
19 Calamagrostis expansa W Maui, Puu Kukui Open bog Preserved_Specimen Ewart III, G.R. 55 Maui BISH 1928-12-20
20 Calamagrostis expansa East Maui, Hana Rain Forest Project, on makai slope of Puu Alaea Among Metrosideros, Vaccinium, Sadleria, and Dryopteris. Preserved_Specimen Harrison, B. 503 Maui BISH 1973-10-10
21 Calamagrostis expansa E Maui, Makawao Distrcdt, Kalialinui ahupuaa, western Piinaau drainage basin In wet transitional mesic forest to subalpine shrubland. Vegetation: Metrosideros, Coprosma, Ilex, Rubus, Lycopodium, Oreobolus, Luzula, Smilax, Carex, Leptecophylla, Vaccinium, Sadleria, Dryopteris, Deschampsia, Uncinia, Anthoxanthum. Preserved_Specimen Scattered individuals. Oppenheimer, H.L. 61012 Maui BISH 2010-06-10
22 Calamagrostis expansa East Maui, Hana District, Wai Anapanapa Hillside below On hillside with Styphelia, Metrosideros, Vaccinium & various ferns. Preserved_Specimen Harrison, B. 434 Maui BISH 1973-08-14
23 Calamagrostis expansa Wai Anapanapa, Haleakala Kipahulu-Kuhiwa divide Thicket at tree line Preserved_Specimen Culms 2-5 in a clump St.John, H. 21036 Maui BISH 1945-08-16
24 Calamagrostis expansa W Maui, Eke Trail From the fringes of the open bogs. Preserved_Specimen A robust erect grass. Hobdy, R.W. 708 Maui BISH 1979-10-24
25 Calamagrostis expansa Wiakea Ahupuaa, Upper Waiakea Forest Reserve, South Hilo District.. Growing in the Upper Waiakea silversword bog (ARGKAU HA-WAU-A) near the edge of a forested kipuka. Growing with Metrosideros polymorpha, Cheirodendron trigynum subsp. trigynum, Deschampsia nubigena, Oreobolus furcatus, Argyroxiphium kauense, Leptecophylla tameiameiae, Carex alligata, Sphagnum palustre. Growing out of SPHPAL near the edge of the bog in the SE corner of the fenced unit. Preserved_Specimen Medium sized clump of grass VanDeMark, J. 78 Hawaii BISH 2024-08-26
26 Calamagrostis expansa East Maui, Hana District, E outer slope of Haleakala, 2 mi NE of Paliku Cabin, Between Wai Anapanapa and Wai Eleele In rain forest Preserved_Specimen Henrickson, J.S. 3572 Maui BISH 1969-06-19
27 Calamagrostis expansa Waianapanapa Haleakala Bogs below Waianapanapa Preserved_Specimen Forbes, C.N. 1185 Maui BISH 1919-08-20
28 Calamagrostis expansa W Maui, Puu Kukui Open bog Preserved_Specimen Ewart III, G.R. 46 Maui BISH 1928-12-20
29 Calamagrostis expansa Puu Kukui Open bog Preserved_Specimen St.John, H. 10264 Maui BISH 1930-02-07
30 Calamagrostis expansa Locality redacted. Contact Bishop Museum Botany Department for details Bogs Preserved_Specimen Forbes, C.N. 1185 Maui BISH 1919-08-20
31 Calamagrostis expansa Wiakea Ahupuaa, Upper Waiakea Forest Reserve, South Hilo District.. Growing in the Upper Waiakea silversword bog (ARGKAU HA-WAU-A) near the edge of a forested kipuka. Growing with Metrosideros polymorpha, Cheirodendron trigynum subsp. trigynum, Deschampsia nubigena, Oreobolus furcatus, Argyroxiphium kauense, Leptecophylla tameiameiae, Carex alligata, Sphagnum palustre. Growing out of SPHPAL near the edge of the bog in the SE corner of the fenced unit. Preserved_Specimen Medium sized clump of grass VanDeMark, J. 78 Hawaii BISH 2024-08-26
32 Calamagrostis expansa W Maui, Lahaina District, Puu Kukui Trail with Metrosideros polymorpha, Styphelia tameiameiae, Sticherus owhyhensis, Broussasia arguta, Dryopteris glabra, Nertera granadensis, Labordia hedyosmifolia, Elaphoglossum wawrae, Carex montis-eeka, Ilex anomala Preserved_Specimen Meidell, J.S. 121 Maui BISH 1996-08-31
33 Calamagrostis expansa W Maui, Puukukui In fringes of bog along the ridge between east bog and Puukukui. Preserved_Specimen Hobdy, R.W. 670 Maui BISH 1979-08-18
34 Calamagrostis expansa W Maui, Puu Kukui Fringe of open bog Preserved_Specimen Munro, G.C. 629 Maui BISH 1916-09-25
35 Calamagrostis expansa Puu Kukui Open bog Preserved_Specimen St.John, H. 10265 Maui BISH 1930-02-07
36 Calamagrostis expansa S. Kona District; Kohala Mts.; above Honokana nui Stream; N of twin Awini bogs Metrosideros-Cheirodendron montane wet forest and Metrosideros-Machaerina montane bogs with Styphelia, Carex alligata, Calamagrostis expansa, Oreobolus furcatus, Dichanthelium cynodon, Stenogyne cranwelliae, Myrsine spp., Rhynchospora chinensis. Threats: Pigs, Juncus spp., Polygonum punctatum. Preserved_Specimen Clumping in sphagnum moss of bogs; 1 m tall; leaves shiny dark-green; mature inflorescence cream brown. Ca. 200 plants. Wood, K.R. 4807 Hawaii BISH 1995-11-28
37 Calamagrostis expansa East Maui, Hana Forest Reserve On hillside below Wai Anapanapa with Styphelia, Vaccinium, Metrosideros, and various ferns. Preserved_Specimen Harrison, B. 277 Maui BISH 1973-06-29
38 Calamagrostis expansa Hana Forest Reserve occasional throughout Forest Reserve area. Preserved_Specimen Loose clump, culum about 7 ft. long; just beginning to flower. Herbst, D.R. 3041 Maui BISH 1973-08-06
39 Calamagrostis expansa S Kohala District; N of Honokane Nui stream. Third bog W of USGS trail near cabin Metrosideros polymorpha var. incana-Machaerina angustifolia montane bogs with Rhynchospora chinensis, Styphelia, Vaccinium, Viola maviensis, Dichanthelium spp., Oreobolus. Bogs bordered by Metrosideros-Cheirodendron montane wet forest. Threats: Pigs, Tibouchina herbacea, Juncus ensifolius. Preserved_Specimen Wood, K.R. 4739 Hawaii BISH 1995-11-15
40 Calamagrostis expansa East Maui, Hana District, Haleakala Nat. Park Divide just below Waianapanpa on trail down into Hana Rain Forest In assoc. with Lysimachia kipahuluensis, Uncinia uncinata, Metrosideros etc. Preserved_Specimen Medeiros, A.C. 179 Maui BISH 1981-09-19
41 Calamagrostis expansa East Maui, Haleakala, Kipahulu-Kuhiwa divide, Wai Anapanapa Opening on ridge Preserved_Specimen Tufted, opening on ridge, one tuft seen. Leaves flat subcoriaceous, striate nerved, above dark shiny green, below pale green, glumes and lemmas with green midribs, the margins white hyaline or pinkish. St.John, H. 29988 Maui BISH 1945-08-13
42 Calamagrostis expansa East Maui, NE rift, Midcamp Bog Growing in Oreobolus tussocks. Preserved_Specimen Medeiros, A.C. 279 Maui BISH 1982-10-01
43 Calamagrostis expansa East Maui, Hana District, Haleakala Bogs below Wai Anapanapa Bogs Preserved_Specimen Forbes, C.N. 1185 Maui BISH 1919-08-20
44 Calamagrostis expansa Hana District. Hana Forst Reserve, headwaters of Kawaipapa Scattered throughout bogs in area, ca. 20 clumps in this bog. Machaerina-Rhynchospora-Racomitrium montane bog W/Dicranopteris linearis, Lycopodiella cernua, Cheirodendron trigynum, Trematobella mcacrostachys, Vaccinium dentatum, Peperomis kipahuluensis, Metrosideros polymorph polymorpha, Viola maviensis,L Preserved_Specimen Grass, culms erect Wood, K.R. 15616 Maui BISH 2013-08-20
45 Calamagrostis expansa East Maui, Hana drainage basin Approximately 20 plants observed in this site, plus 2 others downslope. Vegetation: Metrosideros, Cheirodendron, Coprosma, Vaccinium, Leptecophylla, Hydrangea, Smilax, Rubus, Diplopterygium, Dryopteris, Asplenium, Athyrium, Dubautia, Peperomia, Deschampsia, Cyperus, Lepisorus, Adenophorus, Sadleria, Elaphoglossum, Luzula. Preserved_Specimen Oppenheimer, H.L. 92119 Maui BISH 2021-09-15
46 Calamagrostis expansa W Maui, Mt. Kukui Open bog Preserved_Specimen Munro, G.C. 624 Maui BISH 1916-09-25
47 Calamagrostis expansa S rim of Kipahulu Valley, Kuiki, Haleakala In mossy openings on windward crest. Preserved_Specimen Culms solitary or a few together, subrepent at base. St.John, H. 21241 Maui BISH 1945-08-30
48 Calamagrostis expansa S Kohala District; N of Honokane Nui stream Metrosideros polymorpha var. incana-Machaerina angustifolia montane bogs with Rhynchospora chinensis, Styphelia, Vaccinium by Metrosideros-Cheirodendron montane wet forest. Threats: Pigs, Tibouchina herbacea, Juncus ensifolius. Preserved_Specimen Wood, K.R. 4751 Hawaii BISH 1995-11-15
49 Calamagrostis expansa Haleakala, N slope of Haleakala Preserved_Specimen Stem 2.52-3.29 m long. Dark green with very slight gloucous line, joints dark purplle, outer glume with green centre and straw wheat edges, awns with slight pink tinge at the tips. Forbes, C.N. 1163 Maui BISH 1919-08-17
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