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Rhynchospora rugosa

(Claybank Beaksedge)

Interesting Facts

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Common Names

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Common Names in English:

Claybank Beaksedge

Description

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Family Cyperaceae

Herbs, annual or perennial , cespitose or not, rhizomatous or not, stoloniferous or not. Roots fibrous , principally adventitious. Stems (culms ) usually trigonous , occasionally terete , rarely compressed , usually solid, rarely hollow or septate . Leaves basal and/or cauline, alternate, usually 3-ranked, rarely 2-ranked or multi-ranked, bases forming cylindric sheaths enclosing stem, margins usually fused; junction of sheaths and blades often with adaxial flaps of tissue or fringes of hair (ligules) ; blades frequently absent from some basal leaves , rarely from cauline leaves, when present divergent or ascending , flat, folded, plicate , rolled, or terete, linear , venation parallel. Primary inflorescences (spikelets ) a shortened axis; glumaceous bracts (scales ) 1-many, spirally arranged , sometimes 2-ranked, usually appressed or ascending; scales usually all fertile , each subtending a single flower, sometimes proximal and/or distal scales empty; lateral spikes often with basal, usually empty, usually 2-keeled scale (prophyll) ; occasionally prophyll subtending and enclosing rachilla, bearing 1 pistillate , sometimes (0-) 3 staminate flowers and empty scales (Carex, Cymophyllus, and Kobresia) . Secondary inflorescences panicles, often modified to corymb, pseudoumbel, cyme (anthela), raceme , spike, or capitulum (head ), rarely single spike, usually subtended by foliaceous or, less frequently, glumaceous bracts; secondary inflorescences sometimes simulating spikelets (Carex, Cymophyllus, and Kobresia) . Flowers hypogynous, bisexual in most genera, unisexual in Scleria, Carex, Cymophyllus, and Kobresia; perianth absent or with (1-) 3-6(-30) bristles and/or scales, usually falling off with fruit; stamens usually (1-) 3, rarely more, usually distinct ; anthers basifixed ; pistils 1, 2-3(-4) -carpellate, fused, locule 1; style undivided or branches 2-3(-4) ; stigma sometimes papillate . Fruits achenes, usually trigonous or biconvex ; pericarps thin (except in Scleria) . Seeds 1; testa thin, free from pericarp; embryo basal; endosperm abundant. x = 5-ca. 100.

Genera ca. 100, species ca. 5000 (27 genera, 843 species in the flora ) : worldwide.

No consensus exists regarding the number of genera and the overall relationships of genera within Cyperaceae. The most recent account of the family (P. Goetghebeur 1998) recognized 104 genera distributed among 4 subfamilies and 14 tribes . That arrangement differs somewhat from that of J. Bruhl (1995) . With one minor exception the arrangement of the family here follows that of Goetghebeur.

The family is characterized by the occurrence of a number of unusual cytological features including: (1) chromosomes with diffuse centromeres , (2) post-reductional meiosis, and (3) pollen grains formed from tetrads in which 3 of the 4 microspores fail to develop. The first two features are found in at least some Juncaceae and are unique to the two families. Juncaceae also have pollen in tetrads, but in that family all four microspores produce pollen grains. Some species in some genera of Cyperaceae (particularly Eleocharis) possess chromosomes with localized centromeres (S. S. Bir et al. 1993) . The wide range of chromosome numbers found in Cyperaceae is largely because of agmatoploidy; polyploidy has been hypothesized for some genera, especially Eleocharis, although polyploidy has not been demonstrated unequivocally.

Because of morphologic similarities in vegetative and inflorescence characters, the family has commonly been associated with Poaceae. Cytological features discussed above clearly indicate that to be a superficial similarity . Data from rbcL studies also support the view that Cyperaceae and Poaceae are not closely related (M. R. Duvall et al. 1993b; G. M. Plunkett et al. 1995) ; they do support the concept of close relationship between Cyperaceae and Juncaceae.

For most families of flowering plants the phenological data given are flowering times. Because most Cyperaceae cannot be reliably identified when in flower, in this volume fruiting time is given for all species by season , sometimes qualified by early, mid, or late, or by months. The fruiting time has been interpreted broadly to include the period when the fruit is more or less fully formed but not yet ripe . The fruiting period provided covers the entire range of the taxon . Quite a difference between fruiting periods in different parts of the range of the species may well occur, especially for widespread species and species with extensive elevation range.

For a recent, comprehensive review of the economic importance of Cyperaceae, see D. A. Simpson and C. A. Inglis (2001) .[1]

Genus Rhynchospora

Herbs, annual or perennial , cespitose or not, often scaly-rhizomatous. Culms procumbent to erect , usually trigonous , wiry to stout. Leaves basal and cauline, polystichous , mostly 3-ranked; sheaths open apically, glabrous ; ligules present or absent; blades flat, V-shaped in cross section or terete , typically keeled abaxially, margins involute or revolute , usually scabrid or scabridulous . Inflorescences terminal , rarely pseudolateral, paniculate , corymbose , anthelate , racemose, or capitate; spikelets 3-100 or more; involucral bracts 1-6, spreading or rarely the proximal erect, leaflike. Spikelets: scales spirally or distichously arranged, each subtending flower; 1 or more proximal scales empty. Flowers all bisexual or sometimes distalmost staminate ; perianth absent or of 2-12(-20) bristles , usually persistent in fruit, rarely deciduous, variously barbed or plumed, shorter or longer than achene, seldom smooth ; stamens 2-3; styles undivided or shallowly 2-fid, or deeply cleft into 2(-3) linear stigmatic branches; style base persistent as tubercle on fruit, usually articulate to achene apex, distinct , enlarged. Fruits achenes, borne on pedicellar joint , directly distal to compact , dilated receptacle; body various shades of brown, flattened, lenticular (biconvex ), or nearly terete, smooth and lustrous or variously ridged , pitted , alveolate (honeycombed ), cancellate (netted , latticed), papillate , or warty; tubercle mostly conic or variously triangular, terete or flattened and 2-edged, sometimes longitudinally sulcate , widest across base ; base along narrow transverse suture, lunate , 2-lobed, or topping achenial "neck" or buttress , much narrower, as wide as, or wider than achene apex, decurrent down achene margins.

Species over 250: worldwide, mostly in sunny places with wet, acidic soils.

The working basis for the classification used here is from G. Kükenthal, the first modern monographer of Rhynchospora worldwide (19491951). He divided the genus into two subgenera , Haplostylae (Nees) Bentham and Diplostylae Bentham, based on degree of stylar branching. In subg. Haplostylae the stylar apex is virtually unlobed, surmounted by two tubercle like stigmas, or shallowly bifid with the stigmatic branches rarely approaching 1 mm. Thus the stigmatic area is small compared to that of plants in subg. Diplostylae, in which the stylar apex is divided into two narrowly linear, elongate stigma branches.

Most members of Rhynchospora are cespitose. This does not preclude the possibility of some species (e.g. , R. caduca, R. mixta) from having well developed scaly rhizomes or others (e.g., R. oligantha, R. breviseta, R. rariflora, R. stenophylla) from forming dense, hard-based tufts from packed, intertwined short rhizomes. Only a few species are strongly clonal by elongate rhizomes; those are mostly in subg. Haplostylae (e.g., R. tracyi, R. careyana, R. inundata) or subg. Diplostylae sect. Dichromena (e.g., R. colorata).

Rhynchosporas are often dominant or co-dominant herbaceous graminoids in marshlands and savannas . Many species occuring in marshlands provide food for migratory waterfowl.[2]

Physical Description

Habit: Graminoid

Habitat

Typically found at an altitude of 0 to 2,770 meters (0 to 9,088 feet).[3]

Biology

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Reproduction

Duration: Perennial

Taxonomy

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Synonyms

Schoenus rugosus Vahl

Notes

Name Status: Accepted Name .

Last scrutiny: 21-Jun-2005

Similar Species

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Members of the genus Rhynchospora

ZipcodeZoo has pages for 112 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

R. alba (White Beaksedge) · R. baldwinii (Baldwin's Beaksedge) · R. berteroi (Little Beaksedge) · R. brachychaeta (West Indian Beaksedge) · R. breviseta (Shortbristle Beaksedge) · R. caduca (Anglestem Beaksedge) · R. californica (California Beaksedge) · R. capillacea (Horned Beakrush) · R. capitellata (Brownish Beakrush) · R. careyana (Broadfruit Horned Beaksedge) · R. cephalantha (Bunched Beaksedge) · R. cephalantha var. cephalantha (Bunched Beaksedge) · R. chalarocephala (Loosehead Beaksedge) · R. chalarocephala Fern. & Gale var. chalarocephala Fern. & Gale (Loosehead Beaksedge) · R. chalarocephala var. angusta (Loosehead Beaksedge) · R. chalarocephala var. chalarocephala (Loosehead Beaksedge) · R. chapmanii (Chapman's Beaksedge) · R. chinensis (Spiked Beaksedge) · R. chinensis subsp. spiciformis (Spiked Beaksedge) · R. ciliaris (Fringed Beaksedge) · R. colorata (Starrush Whitetop) · R. compressa (Flatfruit Beaksedge) · R. corniculata (Short-Bristled Horned Beak-Sedge Rhynchospora Corniculata) · R. corniculata var. corniculata (Shortbristle Horned Beaksedge) · R. corymbosa (Matamat) · R. crinipes (Mosquito Beadsedge) · R. culixa (Georgia Beaksedge) · R. curtissii (Curtiss' Beaksedge) · R. debilis (Savannah Beaksedge) · R. decurrens (Swampforest Beaksedge) · R. divergens (Spreading Beaksedge) · R. elliottii (Elliott's Beaksedge) · R. eximia (Florida Beaksedge) · R. fascicularis (Fascicled Beaksedge) · R. fascicularis var. distans (Fascicled Beaksedge) · R. fascicularis var. fascicularis (Fascicled Beaksedge) · R. fernaldii (Fernald's Beaksedge) · R. filifolia (Threadleaf Beaksedge) · R. floridensis (Florida Whitetop) · R. fusca (Brown Beaksedge) · R. gigantea (Giant Beaksedge) · R. globularis (Globe Beakrush) · R. globularis var. globularis (Globe Beaksedge) · R. globularis var. pinetorum (Globe Beaksedge) · R. globularis var. saxicola (Stone Mountain Beaksedge) · R. glomerata (Clustered Beaksedge) · R. glomerata var. glomerata (Clustered Beaksedge) · R. gracilenta (Slender Beaksedge) · R. grayi (Gray's Beaksedge) · R. harperi (Harper's Beaksedge) · R. harveyi (Harvey's Beaksedge) · R. hispidula (Hairy Beaksedge) · R. holoschoenoides (Fly Beaksedge) · R. inexpansa (Nodding Beaksedge) · R. intermedia (Pinebarren Beaksedge) · R. inundata (Narrowfruit Horned Beaksedge) · R. jamaicensis (Jamaican Beaksedge) · R. knieskernii (Knieskern's Beaked-Rush) · R. kunthii (Kunth's Beaksedge) · R. latifolia (Sandswamp Whitetop) · R. lindeniana (Bahama Beaksedge) · R. lindeniana var. bahamensis (Bahama Beaksedge) · R. lindeniana var. lindeniana (Linden Beaksedge) · R. longiflora (Longleaf Beaksedge) · R. macra (Large Beaksedge) · R. macrostachya (Tall Horned Beaksedge) · R. macrostachya var. macrostachya (Tall Horned Beaksedge) · R. marisculus (Caribbean Beaksedge) · R. megalocarpa (Sandyfield Beaksedge) · R. micrantha (Tropical Beaksedge) · R. microcarpa (Southern Beaksedge) · R. microcephala (Smallhead Beaksedge) · R. miliacea (Millet Beaksedge) · R. mixta (Mingled Beaksedge) · R. nervosa ciliata (Yerba De Estrella) · R. nervosa subsp. ciliata (Yerba De Estrella) · R. nitens (Shortbeak Beaksedge) · R. nivea (Showy Whitetop) · R. odorata (Fragrant Beaksedge) · R. oligantha (Featherbristle Beaksedge) · R. pallida (Pale Beaksedge) · R. perplexa (Pineland Beaksedge) · R. perplexa var. perplexa (Pineland Beaksedge) · R. pleiantha (Coastal Beaksedge) · R. plumosa (Plumed Beaksedge) · R. podosperma (Bird Beaksedge) · R. polyphylla (Leafy Beaksedge) · R. punctata (Dotted Beaksedge) · R. pusilla (Beak-Rush) · R. racemosa (Racemed Beaksedge) · R. radicans microcephala (Tropical Whitetop) · R. radicans subsp. microcephala (Tropical Whitetop) · R. rariflora (Fewflower Beaksedge) · R. recognita (Globe Beaksedge) · R. rubra (Rhynchospora) · R. rufa (Red Beaksedge) · R. rugosa (Claybank Beaksedge) · R. rugosa lavarum (Claybank Beaksedge) · R. rugosa subsp. lavarum (Claybank Beaksedge) · R. scirpoides (Longbeak Beaksedge)

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 22, 2007:

Identifiers

Footnotes

  1. Peter W. Ball, A. A. Reznicek, David F. Murray "Cyperaceae". in Flora of North America Vol. 23 Page 3, 4, 192, 243, 252. Oxford University Press. Online at EFloras.org. [back]
  2. Robert Kral "Rhynchospora". in Flora of North America Vol. 23 Page 6, 7, 200, 201, 231, 238. Oxford University Press. Online at EFloras.org. [back]
  3. Mean = 439.310 meters (1,441.306 feet), Standard Deviation = 1,080.060 based on 340 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/15/2012