Eleocharis R.Br.

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Small to large annual or perennial glabrous blade-less herbs; stems usually terete or triangular, hollow or pith-filled, sometimes with transverse septa

Morphology Leaves Leaf sheaths

Leaf-sheaths usually pale brownish, but often purple at the base, tubular, truncate above and ending in a short triangular or lanceolate lobe

Morphology Reproductive morphology Inflorescences

Inflorescence a single terminal ovate to lanceolate, rarely almost globose, spikelet; leafy involucral bracts absent

Morphology Reproductive morphology Inflorescences Bracts Glume

Fertile glumes spirally arranged and imbricate, usually numerous, pale grey to dark brown Lower 1–2 glumes of spikelet sometimes much stiffer than the fertile glumes

Morphology Reproductive morphology Flowers Perianth

Perianth of 3–9 bristles shorter or longer than the nutlet, or absent

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 1–3

Morphology Reproductive morphology Flowers Gynoecium Style

Style with 2–3 branches

Morphology Reproductive morphology Fruits

Nutlet obovate or urn-shaped, whitish, brown or black, smooth, reticulate, pitted or longitudinally grooved with transverse ridges, with the style base persistent as a conical or flattened appendage.

Distribution

About 300 species in all tropical and temperate parts of the world, but with most species in America.

Cyperaceae, K Hoenselaar, B. Verdcourt & H. Beentje. Hypolytrum, D Simpson. Fuirena, M Muasya. Flora of Tropical East Africa. 2010

Note

Sometimes spelled Heleocharis, but this is not correct

Morphology General Habit

Annual or perennial herbs, glabrous.

Vegetative Multiplication Rhizomes

Rhizome often strong, horizontal, and often producing stolons

Morphology Culms

Culms green and photosynthesizing, hollow or filled with pith, rarely with transverse septa

Morphology Leaves

Leaves reduced to scarious scales on stem base and to tubular sheaths, truncate or ending in a short lobe

Morphology Reproductive morphology Inflorescences

Inflorescence a single terminal spikelet 0.1–50 mm long, or sometimes the spikelet aborted and only a scar present; lowest 1–2 glumes equal to or different from the upper.

Morphology Reproductive morphology Inflorescences Bracts Glume

Glumes spirally arranged, imbricate, florets bisexual but the lowermost 1–2 glumes usually sterile, glabrous, often with pale border and midrib

Morphology Reproductive morphology Flowers Perianth

Perianth of 3–9 bristles, or reduced to a minute basal rim to the ovary/nutlet

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 1–3

Morphology Reproductive morphology Flowers Gynoecium Style

Style with swollen base, persistent in fruit, and with 2–3 branches, sometimes varying even within a single plant, the branches with beaded hairs (unicellular with annular constrictions)

Morphology Reproductive morphology Fruits

Nutlet obovoid or urn-shaped, with base of style persistent and often separated from main fruit body by a constriction, pitted or grooved longitudinally with transversal ridges.

Ecology

Mostly in the Americas. Wet or seasonally inundated habitats.

J. Browning, K.D. Gordon-Gray†, M. Lock, H. Beentje, K. Vollesen, K. Bauters, C. Archer, I. Larridon, M. Xanthos, P. Vorster, J. Bruhl, K. Wilson and X. Zhang (2020). Flora Zambesiaca Volume: 14: Cyperaceae. M.Á. García, J.R. Timberlake (Eds). Kew Publish

Morphology Culms

Culms erect, 0.5–1 m tall, usually numerous, hollow or pith- filled, occasionally septate; leaves reduced to inconspicuous sheaths basal to culms

Morphology General Habit

Short-lived perennials appearing leafless; tufted with numerous spikelet-terminated, slender nodeless culms mostly under 0.5 m tall, often producing slender, white rhizomes branching and sometimes with small tubers Annual or perennial herbs, robust to medium sized; rhizome stout to slender, horizontally creeping; or compactly uniseriate

Note

These are inconspicuous, easily broken and often do not persist in herbarium material. Annuals similar but lacking rhizomes or above ground stolons, aerial organs delicate and sometimes very small

Morphology Reproductive morphology Inflorescences

Inflorescence throughout a solitary terminal spike (spikelet) of one, few or many bisexual florets, florets spirally placed when numerous

Morphology Reproductive morphology Inflorescences Bracts Glume

Glumes imbricate to fairly loose, lowest 2 sometimes sterile, resembling greenish enveloping bracts, or bracts undeveloped

Morphology Reproductive morphology Flowers Perianth

Perianth of 3–9 barbellate, marginally toothed or smooth bristles, sometimes absent, or reduced to a narrow rim underlying ovary

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 1–3

Morphology Reproductive morphology Flowers Gynoecium Style

Style base enlarged, usually persistent as conical or flattened appendage on nutlet; style 2–3 branched, variable even in individual spikelets; upper portion deciduous, base persistent as appendage to nutlet

Morphology Reproductive morphology Fruits

Nutlets obovoid, biconvex or trigonous, longitudinally 3-ridged, smooth, variously patterned, or with pits placed in longitudinal rows.

Distribution

A genus of about 250 species, mostly American, in permanently to periodically wet habitats.

Recognition

The genus is most easily recognised by its inflorescence – a terminal spike, usually quite short and visibly ebracteate (a spikelet), sometimes pseudoviviparous. Culms are nodeless and photosynthetic, replacing the reduced leaves each of prophyll and sheath at culm base. Detail of persistent style base is not reliable in species identification as the rim curls upward on drying and the body shrinks; ideally both stages should be described. Nutlet measurements given in the descriptions exclude the style base.

Cyperaceae, K Hoenselaar, B. Verdcourt & H. Beentje. Hypolytrum, D Simpson. Fuirena, M Muasya. Flora of Tropical East Africa. 2010

Morphology General Habit

Submerged perennial aquatic plants rooting in mud.

Morphology Culms

Culms much-branched, many-noded with many sterile stems in successive whorls and only occasional fertile culms

Morphology Leaves

Leaves a tubular sheath

Morphology Reproductive morphology Inflorescences

Inflorescence a single spikelet

Morphology Reproductive morphology Inflorescences Spikelets

Spikelets of 2 glumes and a single bisexual flower.

Morphology Reproductive morphology Flowers Perianth

Perianth-segments 6–11, filiform with many recurved spines.

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3 with large anthers

Morphology Reproductive morphology Flowers Gynoecium Style

Style 2-branched

Morphology Reproductive morphology Fruits

Nutlets broadly ovoid or round, flattened, with small persistent style-base

J. Browning, K.D. Gordon-Gray†, M. Lock, H. Beentje, K. Vollesen, K. Bauters, C. Archer, I. Larridon, M. Xanthos, P. Vorster, J. Bruhl, K. Wilson and X. Zhang (2020). Flora Zambesiaca Volume: 14: Cyperaceae. M.Á. García, J.R. Timberlake (Eds). Kew Publish

Morphology General Habit

Perennial herbs, submerged or floating

Morphology Culms

Culms elongate, many-noded, frequently branched, with whorls of vegetative branchlets subtended by small bract scales; occasionally intermingled with more robust fertile whorls with single terminal spikelets

Morphology Leaves

Leaves basal to branchlets, reduced to tubular sheaths

Morphology Reproductive morphology Inflorescences

Inflorescences often emergent, a single spikelet terminal on each branch, 1-flowered, bisexual-Glumes 2, distichous, elongate, eventually deciduous; lower barren, upper subtending floret

Morphology Reproductive morphology Flowers Perianth

Perianth of bristles disseminated with nutlet

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 3

Morphology Reproductive morphology Flowers Gynoecium Style

Style branches 2

Morphology Reproductive morphology Fruits

Nutlets ovoid, crowned by flattened persistent style base.

Distribution

A monotypic genus widely distributed in tropical Asia, Africa and Americas.