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FOC | Family List | FOC Vol. 23 | Cyperaceae

11. Eleocharis R. Brown, Prodr. 224. 1810.

荸荠属 bi qi shu

Authors: Lun-Kai Dai & Mark T. Strong

Herbs, perennial or annual. Rhizomes short or absent; stolons usually present. Culms tufted or single. Leaves bladeless; sheath apiculate or rarely with a scarious appendage at apex. Inflorescences reduced to a single terminal spikelet, erect, rarely proliferous (bearing plantlets) at base, with few to many bisexual flowers. Glumes spirally imbricate or rarely distichous, oblong, oblong-ovate, lanceolate, or subrounded, firm or membranous, glabrous, usually with a midvein although sometimes indistinct but with lateral veins, margin usually hyaline; basal 1 or 2 glumes usually empty. Perianth bristles (3-)6(-12) or rarely absent, retrorsely spinulose. Stamens 1-3. Style thin; stigmas 2 or 3. Nutlet obovoid, broadly obovoid, or globose-obovoid, 3-sided, biconvex, or plano-convex, smooth, reticulate, cancellate, or rarely pitted; persistent style base expanded, triangular, conic, or variously shaped, sometimes spongy-thickened.

About 250 species: worldwide; 35 species (nine endemic) in China.

1 Spikelet usually cylindric or narrowly ellipsoid, as wide as culms; culms usually stout, sometimes transversely septate with nodes evident on surface (in E. dulcis); leaf sheath mouth oblique; glumes firm, subcartilaginous, rarely subpapery or membranous, midvein obscure or indistinct but with 15 or more prominent to obscure close longitudinal veins   (2)
+ Spikelet ovoid to narrowly ovoid, rarely cylindric, usually wider than culms; culms slender, nodes not evident on surface; leaf sheath mouth truncate or slightly oblique, rarely with a scarious appendage; glumes generally membranous, midvein distinct or rarely obscure   (7)
2 (1) Culms with transverse septa, nodes evident on surface when dry; spikelet with basal 2 glumes empty, rarely 1 with a flower; nutlet surface essentially smooth.   1 E. dulcis
+ Culms without transverse septa, nodes not evident on surface when dry; spikelet with only basalmost glume empty; nutlet surface cancellate or reticulate   (3)
3 (2) Culms terete.   6 E. ochrostachys
+ Culms 3-angled, rarely acutely 4- or 5-angled   (4)
4 (3) Culms firm, with pith in center; glumes broadly ovate or subquadrate, as long as wide   (5)
+ Culms spongy, subhollow; glumes narrowly ovate or broadly lanceolate, ca. 2 × as long as wide   (6)
5 (4) Leaf sheath mouth with setaceous appendage; glumes densely imbricate, subquadrate, apex truncate; nutlet apex not constricted; perianth bristles as long as or shorter than nutlet.   2 E. spiralis
+ Leaf sheath mouth acute but without an appendage; glumes laxly imbricate, broadly ovate, apex rounded; nutlet apex constricted; perianth bristles ca. 2 × as long as nutlet.   3 E. trilateralis
6 (4) Culms 3-angled, (1-)3-4 mm thick; spikelet 1.5-4 cm × 3-5 mm; glumes broadly ovate, 3-3.5 mm wide, subleathery, apex rounded; nutlet surface shallowly pitted with 13-15 longitudinal rows of transversely oriented, oblong to linear epidermal cells.   4 E. acutangula
+ Culms acutely 4- or 5-angled, 1.5-2.5 mm thick; spikelet 2-5 cm × 2.5-3 mm; glumes broadly lanceolate, 1.5-2.5 mm wide, membranous, apex obtuse to slightly acute; nutlet surface deeply pitted with 15-20 longitudinal rows of hexagonal epidermal cells.   5 E. philippinensis
7 (1) Persistent style base scarcely differentiated from nutlet apex and seemingly a continuation of it   (8)
+ Persistent style base differentiated from nutlet apex by a constriction or articulation at junction with it   (10)
8 (8) Annuals, neither stoloniferous or rhizomatous; culms often recurved; persistent style base pyramidal-acuminate; nutlet narrowly winged on angles, reticulate to deeply pitted-reticulate with isodiametric epidermal cells   9 E. retroflexa
+ Perennials, stoloniferous; culms erect to ascending; persistent style base triangular-subulate or subconic; nutlet not winged on angles, essentially smooth   (9)
9 (8) Culms 1-7 cm tall; spikelets 2-4 mm, 6-10-flowered; persistent style base triangular-subulate; nutlet. 9-1.5 mm, smooth.   7 E. parvula
+ Culms 3-30 cm tall; spikelets 4-7 mm, 2-7-flowered; persistent style base subconic to 3-angled-subulate; nutlet 1.9-2.5 mm, appearing smooth but finely cellular-reticulate.   8 E. quinqueflora
10 (7) Stigmas 3   (11)
+ Stigmas 2   (19)
11 (10) Culms short and very slender; spikelet few flowered; glumes subdistichous at base of spikelet; nutlet terete or nearly so, longitudinally ridged with ridges separated by numerous cross-walls (trabeculae).   10 E. yokoscensis
+ Culms elongate and ± stout; spikelet many flowered; glumes spirally imbricate; nutlet 3-sided to compressed 3-sided, essentially smooth   (12)
12 (11) Culms acutely (3 or)4(-6)-angled; spikelet not proliferous at base; nutlet brownish when mature   (13)
+ Culms terete; spikelet usually proliferous at base; nutlet olivaceous or yellowish when mature   (14)
13 (12) Glumes 3-4 × 1-1.5 mm, margin narrow and hyaline; nutlet 1.2-1.5 mm and as wide; perianth bristles laxly to densely retrorsely spinulose; persistent style base deltoid, 1/2-2/3 as long as nutlet.   11 E. tetraquetra
+ Glumes 4-6 × 2-2.5 mm, margin broad and hyaline; nutlet 1.5-2 mm and as wide; perianth bristles plumose with spreading hairs; persistent style base narrowly ovoid, as long and as wide as nutlet or nearly so.   12 E. wichurae
14 (12) Glumes ovate-lanceolate, 3-4 mm, apex acute; persistent style base narrowly 3-angled to conic, attenuate to a short caudal tip, ca. 1/2 as long as nutlet; rhizome decumbent or obliquely ascending.   13 E. yunnanensis
+ Glumes oblong, suboblong, ovate, or elliptic, 1.5-2.5 mm, apex obtuse or rounded; persistent style base 3-angled, pyramidal, deltoid, narrowly ovoid, or subconic, ca. 1/4 as long as nutlet; rhizome absent or present   (15)
15 (14) Persistent style base depressed, deltoid-pyramidal, as wide as nutlet or nearly so.   17 E. attenuata
+ Persistent style base not depressed, deltoid, narrowly ovoid, or subconic, often shortly attenuate to apex, ca. 1/2 as wide as nutlet   (16)
16 (15) Perianth bristles exceeding tip of style base.   18 E. congesta
+ Perianth bristles shorter than tip of style base   (17)
17 (16) Annuals; spikelet narrowly ovoid, oblong-ovoid, cylindric, or rarely globose-ovoid, (3-)5-10 mm, several to many flowered; glumes oblong.   14 E. pellucida
+ Perennials; spikelet ovoid or ovoid-cylindric, 2.5-6 mm, few flowered; glumes ovate or elliptic   (18)
18 (17) Perianth bristles 6, slightly shorter than nutlet; nutlet obovoid, ca. 1 mm.   15 E. maximowiczii
+ Perianth bristles 2-5, 1/4-1/2 as long as nutlet; nutlet oblong to oblong-obovoid, ca. 1.5 mm.   16 E. setulosa
19 (10) Annuals; persistent style base not spongy-thickened; stolons absent; spikelet ovoid, subglobose, or oblong-ovoid, (2-)3-5(-8) mm   (20)
+ Perennials; persistent style base spongy-thickened but rarely obscurely so; stolons often present; spikelet narrowly ovoid, narrowly oblong-ovoid, or ellipsoid-cylindric, (3-)7-25 mm   (22)
20 (19) Persistent style base dorsiventrally compressed, deltoid; nutlet brownish at maturity.   19 E. ovata
+ Persistent style base depressed conic or saucer-shaped; nutlet black at maturity and lustrous   (21)
21 (20) Nutlet 0.7-1.1 mm; perianth bristles 6-8, rust-colored; persistent style base depressed conic, slightly reflexed basally on both sides.   20 E. geniculata
+ Nutlet 0.3-0.6 mm; perianth bristles 4-6, colorless or white; persistent style base saucer-shaped, not reflexed basally.   21 E. atropurpurea
22 (19) Basalmost glume empty, suborbicular, spathiform, usually completely encircling base of spikelet   (23)
+ Basal 2 or 3 glumes empty, basalmost encircling 1/2 or less of spikelet base   (28)
23 (22) Persistent style base large, mitriform, cellular-spongy, ovoid, more than 2/3 to as long as nutlet.   30 E. kamtschatica
+ Persistent style base conic, broadly ovoid, deltoid, 3-angled, or depressed, less than 1/2 as long as nutlet   (24)
24 (23) Persistent style base depressed, subpatelliform (disk-shaped).   31 E. fennica
+ Persistent style base shallowly conic-ovoid, obtusely 3-angled, low conic, or shortly 3-angled   (25)
25 (24) Glumes oblong-ovate to oblong-lanceolate; persistent style base shallowly conic-ovoid, nearly as long as wide, nearly 1/2 as long as nutlet.   32 E. uniglumis
+ Glumes ovate; persistent style base obtusely 3-angled or low conic, shorter than or nearly as long as wide, 1/4-1/3 as long as nutlet   (26)
26 (25) Persistent style base obtusely 3-angled, nearly as long as wide, ca. 1/3 as wide as nutlet; perianth bristles 4, slightly longer than nutlet.   33 E. penchaoi
+ Persistent style base low conic or shortly 3-angled, shorter than wide, ca. 1/2 as wide as nutlet; perianth bristles 4-6, slightly shorter to slightly longer than nutlet   (27)
27 (26) Culms 8-25 cm tall; spikelet 3-4 mm wide; glumes ovate to broadly ovate, ca. 3 mm, apex acute; perianth bristles as long as or slightly longer than nutlet.   34 E. erhaiensis
+ Culms 25-30 cm tall; spikelet 2-3 mm wide; glumes ovate to oblong-ovate, ca. 4 mm, apex obtuse; perianth bristles slightly shorter than nutlet.   35 E. qinghaiensis
28 (22) Persistent style base oblong-ovoid to oblong-conic, much longer than wide.   29 E. palustris
+ Persistent style base shortly conic, globose-ovoid, broadly ovoid, subquadrate, or globose, as wide as or wider than long   (29)
29 (28) Leaf sheaths scarious (at least apical ones), mouth with a deep sinus ventrally.   26 E. argyrolepis
+ Leaf sheaths herbaceous, mouth truncate to obliquely truncate   (30)
30 (29) Spikelet broadly ovoid to oblong, 3-8 mm, few flowered.   27 E. abnorma
+ Spikelet oblong to oblong-lanceolate, (7-)10-30 mm, many flowered   (31)
31 (30) Glume apices obtuse to subrounded; persistent style base broadly ovoid, rounded-ovoid, subquadrate, or globose   (32)
+ Glume apices acute to subacute; persistent style base shortly conic, conic, or globose   (33)
32 (31) Glumes ovate to oblong-ovate; nutlet globose-obovoid; persistent style base broadly ovoid.   28 E. valleculosa
+ Glumes oblong to linear-oblong; nutlet usually ellipsoid; persistent style base globose-ovoid to subquadrate.   22 E. liouana
33 (31) Persistent style base globose or wider than long, mammiform or mitriform (cap-shaped).   25 E. mitracarpa
+ Persistent style base shortly conic to conic   (34)
34 (33) Glumes oblong-lanceolate; nutlet obovoid,. 7-0.8 mm wide; persistent style base narrowly conic.   23 E. migoana
+ Glumes ovate to oblong-ovate or ovate-lanceolate; nutlet broadly obovoid to orbicular-obovoid, 1-1.3 mm wide; persistent style base depressed conic or shortly conic.   24 E. ussuriensis

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