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Eleocharis exigua

(Kunth) Roem. & Schult. (1817)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Monocots Order: Poales Family: Cyperaceae Genus: Eleocharis

radical fiber optic spikerush, rooted spikerush, spikerush

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Description

Key Characters:

Growth Form: Perennials, forming mats, stolons slender.

Stems: Culms pale green, soft, spongy, filiform, 3–8 cm tall, ca. 0.3 mm in diameter.

Roots:

Leaves: Leaves simple. Leaves basal or nearly so, reduced to bladeless sheaths. Margins entire. Sheathing; sheaths pale, membranous, 0.5–2 cm long, fugacious. Stipules absent.

Flowers: Flowers in spikelets 5–12–flowered, greenish white, ovoid, 3–4 mm long, ca. 1 mm wide, acute; glumes greenish white or occasionally faintly tinged brown, lanceolate–ovate, 1.2–1.5 mm long, acute to subacute, the keel green. Flowers bisexual (perfect). Calyx of 4 bristles, nearly white, very slender, retrorsely spinulose, longer than the achene. Corolla (petals) absent. Ovary superior; styles base depressed-conical, minute; stigmas 3.

Fruit: Achenes yellow; narrowly obovoid; trigonous; 0.6–0.7 mm long; finely cancellate with several rows of horizontally oblong cells. Seeds 1; seed coat thin; free from pericarp; embryo basal; endosperm abundant.

Ploidy: 2n = 56; 58

Habitat: Naturalized in taro paddies; along streams; and in marshes;.

Elevation Range: 20–1,220 m.

Historical Distribution

Images

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Uses and Culture

USES

Natural History

Statewide Status

Naturalized

Island Status

Kaua'i Naturalized
O'ahu Naturalized
Maui Naturalized
Hawai'i Naturalized

Dispersal Agents


Pollinators

Specimens

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Bibliography

Name Published In: Syst. Veg., ed. 15 bis 2: 154 (1817)

Other References

Wagner et al. 1990:1403 (K, O, M [as E. radicans]); Imada et al. 2000:12 (H); POWO 2025 (Syn. E. radicans = E. exigua)

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Description Recorded By Record Number Island Source Date
1 Eleocharis exigua Koolau Mts.; Kipapa Gulch Preserved_Specimen Selling, O. 2619 Oahu BISH 1938-07-03
2 Eleocharis exigua Waimea Drainage Basin, West side Preserved_Specimen Forbes, C.N. 777 Kauai BISH 1917-07-03
3 Eleocharis exigua East Maui, Hana District, Koolau FR, Kano Stream Disturbed intermittent stream. Vegetation: Metrosideros, Dicranopteris, Diplopterygium, Cheirodendron, Broussaisia, Clidemia, Tibouchina, Paspalum, Kyllinga, Prunella, Cyperus Preserved_Specimen Oppenheimer, H.L. 61517 Maui BISH 2015-06-24
4 Eleocharis exigua Koolau Rannge; summit of Kawailoa-Punaluu Trail Preserved_Specimen Neal, M.C. Oahu BISH 1938-07-03
5 Eleocharis exigua Na Pali Coast, Honopu Valley Growing in water of stream. Preserved_Specimen Common tiny sedge. Corn, C. 371 Kauai BISH 1979-07-17
6 Eleocharis exigua University of Hawaii Campus, across from Falculty Apartments on Dole Street In taro patch. Preserved_Specimen Herbst, D.R. 416 Oahu BISH 1967-04-10
7 Eleocharis exigua Koolau Rannge; head of Kawainui Gulch Occasional on muddy trail. Preserved_Specimen Hosaka, E.Y. 1908 Oahu BISH 1937-05-31
8 Eleocharis exigua Puna District; Wao Kele O Puna In pig wallow in Metrosideros forest with understory of Cibotium, Psychotria, Psidium cattleianum and Melastoma. Preserved_Specimen Lamoureux, C.H. 6095 Hawaii BISH 1990-06-09
9 Eleocharis exigua Volcano, Amaumau Rd Shady, wet roadside Preserved_Specimen Caespitose, it appears these are young plants which have not developed their rhizomes yet. The achene is a perfect match for E. radicans. About 4 plants seen although many more may have been overlooked as this plant is so small Faccenda, K. 2627 Hawaii BISH 2022-08-13
10 Eleocharis exigua Koolau Mts.; Waikane Valley, Koolaupoko In muddy plantings of Ipomoea aquatica. Preserved_Specimen Nagata, K.M. 3789 Oahu BISH 1988-01-16
11 Eleocharis exigua W Maui, Wailuku District, Waikapu Valley In muddy ground along valley bottom in Alien Forest. Preserved_Specimen Oppenheimer, H.L. 50225 Maui BISH 2002-05-27
12 Eleocharis exigua Waialua, Waialua Beach Rd.; private lotus farm Tiny sedge growing in wet mud on pond banks. Preserved_Specimen Imada, C. 9233 Oahu BISH 1992-04-05
13 Eleocharis exigua Keanae Arboretum Taro patches; low small patches among Azolla beds. Preserved_Specimen Hobdy, R.W. 1328 Maui BISH 1982-03-26
14 Eleocharis exigua East Maui, Hana District, Waiohue, near Puaa Kaa Park, along side of Hana Hwy. In wet ground. Preserved_Specimen Oppenheimer, H.L. 50214 Maui BISH 2002-05-04
15 Eleocharis exigua Hamakua District, Waipio Valley, taro farm ca. 2 miles into the valley Small weedy bunching sedge forming thick mats in wetland taro paddy. Preserved_Specimen Imada, C. 9930 Hawaii BISH 1999-06-19
16 Eleocharis exigua East Maui, Makawao District, Koolau Forest Reserve, waikamoi flume Forest below flume, along road margin. Preserved_Specimen Wagner, W.L. 5923 Maui BISH 1988-03-09
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