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Bolboschoenus fluviatilis

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: BolboschoenusView DescriptionDichotomous Key

Habit: Perennial herb, erect, 50--200 cm, rhizomed, tubers durable. Stem: simple, sharply 3-angled, glabrous or angles scabrous, evident internal air cavities 0, not hollow. Leaf: basal and cauline, 3-ranked; sheath closed, long; ligule 0; blade generally present, long, thin, flat, V-shaped near base, keeled abaxially, margin, keel +- scabrous. Inflorescence: 1, terminal, panicle- (or head-) like, appearing with leaves; branches often scabrous; inflorescence bracts like leaf blades, main 1 > inflorescence; spikelets +- ovate, not +- flat, flower bracts spiraled, >= 25, each with 1 flower in axil, +- ovate, membranous to papery, puberulent (glabrous in age), brown to +- colorless, tip notched 0.5--1 mm, generally with curved awn often broken off. Flower: bisexual; perianth of 3--6 bristles, <= fruit, +- straight, stout, barbed; stamens 3, anthers >= 1.5 mm; style 1, thread-like, base not enlarged; stigmas 2--3. Fruit: generally obovate, smooth, brown, mucronate; wall cells small, solid or large, hollow (under dissecting microscope).
Species In Genus: 7--15 species: temperate, subtropics. Etymology: (Greek, bolbos, a bulb, and schoenos a rush, reed, in reference to the tubers) Note: Intermediates (putative hybrids) between species cause major problems in classification, identification.
Unabridged Note: Fruit wall anatomy (+- easily seen with a dissecting microscope in a hand-made section) including diagnostic characters that are correlated with fruit buoyancy and persistence of bristles on shed fruit. Putative interspecific hybridization causes major taxonomic confusion; putative hybrids generally occur with their parents, are intermediate between them in all characters, often bear apparently normal fruit that vary in shape within one spikelet, and form persistent clones.
eFlora Treatment Author: S. Galen Smith
Reference: Browning et al. 1995 Brittonia 47:433--445; Smith 2002 FNANM 23:37--44
Bolboschoenus fluviatilis (Torr.) Soják
Habit: Plant 1--2 m. Stem: 5--15 mm diam. Leaf: sheath tip papery, veined; widest blade 7--22 mm wide. Inflorescence: proximal inflorescence bract 4--15 mm wide; spikelets 10--40, > 1/2 on branches, 10--25 mm, 6--10 mm wide; flower bracts 7--10 mm, awn 2--3 mm, base +- 0.5 mm wide. Flower: perianth bristles tightly attached to, = fruit; anthers yellow; stigmas 3. Fruit: 3.8--5.5 mm, 2--2.9 mm wide, strongly 3-sided, as deep as wide, sinking in water; mucro 0.2--0.8 mm; wall cells small, solid. Chromosomes: 2n=94.
Ecology: Uncommon in California. Fresh water marshes; Elevation: < 1300 m. Bioregional Distribution: NCoRI, n SNH, ScV, CCo, MP; Distribution Outside California: temperate North America except most of southern United States. Flowering Time: Summer
Synonyms: Scirpus maritimus L. var. fluviatilis Torr.; Schoenoplectus fluviatilis (Torr.) M.T. Strong; Scirpus fluviatilis (Torr.) A. Gray
Jepson eFlora Author: S. Galen Smith
Reference: Browning et al. 1995 Brittonia 47:433--445; Smith 2002 FNANM 23:37--44
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)

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Botanical illustration including Bolboschoenus fluviatilis

botanical illustration including Bolboschoenus fluviatilis


Citation for this treatment: S. Galen Smith 2012, Bolboschoenus fluviatilis, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on November 24, 2020.

Citation for the whole project: Jepson Flora Project (eds.) 2020, Jepson eFlora,, accessed on November 24, 2020.

Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson
Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson
Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson
Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson
Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson
Bolboschoenus fluviatilis
click for enlargement
© 2004 Steve Matson

More photos of Bolboschoenus fluviatilis in CalPhotos

Geographic subdivisions for Bolboschoenus fluviatilis:
NCoRI, n SNH, ScV, CCo, MP
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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 occurence).


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

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).