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Eleocharis obtusa

Higher Taxonomy
Family: CyperaceaeView DescriptionDichotomous Key
Habit: Annual, perennial herb, often rhizomed or stoloned, often of wet open places; roots fibrous; monoecious, dioecious, or flowers bisexual. Stem: generally 3-sided, generally solid. Leaf: generally 3-ranked; base sheathing, sheath generally closed, ligule generally 0; blade (0 or) linear, parallel-veined. Inflorescence: spikelets generally arranged in head-, spike-, raceme-, or panicle-like inflorescences; flower generally sessile in axil of flower bract, enclosed in a sac-like structure (perigynium) or generally not. Flower: unisexual or bisexual, small, generally wind-pollinated; perianth 0 or generally bristle like; stamens generally 3, anthers attached at base, 4 chambered; ovary superior, chamber 1, ovule 1, style 2--3(4)-branched. Fruit: achene, 2--3 sided.
Genera In Family: +- 100 genera, 5000 species: especially temperate. Note: Difficult; taxa differ in technical characters of inflorescence, fruit. In Carex and Kobresia, what appear to be individual pistillate flowers in fact are highly reduced inflorescences (whether or not the same applies to staminate flowers is still under debate). In some other works (e.g., FNANM) these are called spikelets, and they are treated as being arranged in spikes. Here and in TJM (1993), what appear to be individual pistillate flowers are called pistillate flowers in Carex (and they are treated as being arranged in spikelets), but spikelets in Kobresia (and they are treated as being arranged into spikes). Though internally inconsistent, the approach here is consistent with traditional usage, and reflects a preference for character states that may be determined in the field. Molecular, morphological, and embryological evidence indicates that Eriophorum crinigerum is to be segregated to a new genus, as Calliscirpus criniger (A. Gray) C.N. Gilmour et al., along with a second, newly described species, Calliscirpus brachythrix C.N. Gilmour et al. (Gilmour et al. 2013); key to genera modified by Peter W. Ball to include Calliscirpus.
eFlora Treatment Author: S. Galen Smith, except as noted
Scientific Editor: S. Galen Smith, Thomas J. Rosatti, Bruce G. Baldwin.
Genus: EleocharisView DescriptionDichotomous Key

Common Name: SPIKERUSH
Habit: Annual, perennial herb, generally forming mats, glabrous, internal air cavities evident; caudex generally 0; rhizomes generally evident, long, scaly, bulb or tuber at tip generally 0. Stem: simple, generally erect, smooth, generally not hollow; tip generally not rooting. Leaf: 2, basal, blades 0 or tooth-like, <= 1 mm. Inflorescence: inflorescence bracts 0; spikelet terminal, 1, generally ovate, not +- flat [(+- flat)], generally not forming plantlets, flowers 3--100+; flower bracts spiraled [(2-ranked)], each with 1 flower in axil, generally ovate, generally brown, generally membranous, smooth, tip generally acute to obtuse, notch 0; basal flower bract generally encircling stem, generally < 1/2 spikelet, flower generally 0. Flower: bisexual; perianth parts reduced to bristles, 0--8, generally +- <= fruit, barbs generally recurved; stamens generally 3; style 1, thread-like, base enlarged, generally persistent on fruit as tubercle. Fruit: generally obovate, generally brown; tubercle (0 or) generally distinct, generally pyramidal.
Etymology: (Greek heleios, dwelling in a marsh, and Charis, grace) Note: Eleocharis lanceolata Fernald, Eleocharis equisetoides Torr. not in California.
eFlora Treatment Author: S. Galen Smith
Reference: Smith et al. 2002 FNANM 23:60--120
Eleocharis obtusa (Willd.) Schult.
Habit: Annual 3--50 cm, tufted; rhizome 0. Stem: 0.2--2 mm diam, cylindric. Leaf: distal sheath firm, persistent, tip obtuse to acute, with tooth-like projection to 0.3 mm. Inflorescence: spikelet (2)5--13 mm, (2)3--4 mm wide; flower bracts 15--150+, (2)3--4 mm. Flower: anthers 0.3--0.6 mm; stigmas 2--3. Fruit: 0.9--1.2 mm, 0.7--0.9 mm wide, 2--3-sided, smooth; tubercle 1/3--1/2 as high as wide, 2/3--9/10 as wide as fruit, flat, adherent to fruit; perianth bristles (0 or) 5--7, +- to generally much exceeding tubercle. Chromosomes: 2n=10.
Ecology: Fresh shores, marshes, seepages, stream beds, disturbed places; Elevation: < 1600? m. Bioregional Distribution: NW, SN, ScV/n SNF, CCo; Distribution Outside California: to southern British Columbia, Quebec, Florida; Hawaii. Flowering Time: Late spring--fall Note: See note under Eleocharis engelmannii.
Synonyms: Eleocharis obtusa var. ellipsoidalis Fernald ex Svenson; Eleocharis obtusa var. gigantea Fernald; Eleocharis obtusa var. jejuna Fernald; Eleocharis obtusa var. peasei Svenson; Scirpus obtusus Willd.
Unabridged Note: Distribution voucher: Inverness, Marin Co., Nobbs & Smith 556, (DAV); vernal pool 2 mi southwestern of Lincoln, Placer Co., Ray Griffiths s.n. (DAV).
Jepson eFlora Author: S. Galen Smith
Reference: Smith et al. 2002 FNANM 23:60--120
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

Previous taxon: Eleocharis montevidensis
Next taxon: Eleocharis ovata

Botanical illustration including Eleocharis obtusabotanical illustration including Eleocharis obtusa

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Citation for this treatment: S. Galen Smith 2012, Eleocharis obtusa, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on July 16, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora,, accessed on July 16, 2024.

Eleocharis obtusa  
var. obtusa
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©2008 Keir Morse
Eleocharis obtusa  
var. obtusa
click for image enlargement
©2008 Keir Morse
Eleocharis obtusa
click for image enlargement
©2003 Steve Matson
Eleocharis obtusa
click for image enlargement
©2003 Steve Matson
Eleocharis obtusa
click for image enlargement
©2003 Steve Matson

More photos of Eleocharis obtusa
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Geographic subdivisions for Eleocharis obtusa:
NW, SN, ScV/n SNF, CCo
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map of distribution 1

(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurrence).


Data provided by the participants of the  Consortium of California Herbaria.

View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month Flowering-Fruiting Monthly Counts

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).