Purple Spike Rush

Eleocharis atropurpurea has been reported from Colorado, Montana, and Virginia; I have not seen voucher specimens.

Plants tufted, without creeping rhizomes. Culms 2–12(–19) cm × 0.2–0.4 mm. Leaves: distal leaf sheaths firm, distally tightly sheathing, apex acute. Spikelets ovoid to ellipsoid, 2–6(–8) × 1–2.5 mm, apex acute; proximal scale with or without flower, not amplexicaulous; floral scales to 100, 15–19 per mm of rachilla, often loosely appressed, dark red-brown to stramineous, ovate to elliptic, 0.6–1.3 × 0.3–0.7 mm, membranous, apex rounded to acute. Flowers: perianth bristles (0–)4–6, typically 4, colorless to whitish, vestigial to 1/2 as long as achene, smooth or spinuliferous; styles 2-fid. Achenes black, obovoid, biconvex, 0.3–0.5 × 0.3–0.4 mm, apex often constricted proximal to tubercle, smooth at 40X. Tubercles stramineous to whitish, umbonate to subconic, 0.1–0.2 × 0.1–0.2 mm, apex acute. 2n = 20.

Annual, 2-15 cm, forming small tufts. Roots fibrous. Stem 0.3-0.5 mm diam., with 5-6 obtuse angles separated by deep grooves. Lower closed sheath 3-5 mm, brown or reddish, upper to 10 mm, green or grey green, base often reddish, with 5-6 green nerves, mouth oblique; blades 0 or tip c. 1 mm. Spike 2-7 x 1-3 mm, ovoid or globose, with c. 30 or more glumes in five spiral rows, all fertile; basal glume not distinct or slightly larger and with more pronounced mid-nerve than in other glumes; glumes 1.1-1.6 mm, cymbiform, with prominent, green mid-nerve not quite reaching obtuse apex, sides brown or dark reddish brown, nerves obscure or missing, margins more or less scarious. Perianth bristles rising from white collar, 4-7 or 0, to as long as nut, white or pale brownish; stamens 1-2, anthers 0.3-0.5 mm. Nut 0.6-0.8 x 0.5-0.6 mm, obovoid, bi-convex, apex rounded, basal part gradually tapering, obscurely or finely reticulate, finally black, glossy; stylopodium much wider than long, c. 0.1 x 0.3 mm, white, clearly constricted from nut.

B.C.; Ala., Calif., Fla., Ga., Iowa, Kans., La., Mich., Mo., Nebr., N.Mex., N.C., Okla., S.C., Tex., Wash.; Mexico; West Indies; Central America; South America; Europe (naturalized); Asia; Africa; Pacific Islands.

Distribution: Pantropical and extending into S Europe, Turkey, Iraq, Afghanistan, Pakistan, Tadjikistan, Uzbekistan, China, Japan; tropical Africa, Madagascar, India, Malaysia, Australia, N and S America.

Fl. Per.: September - October.

Fruiting summer–fall (Jun–Sep).

Canal banks, hammocks, irrigation ditches, lake and pond margins, maritime shores, rice fields; 0–1800m.

Rice fields, wet meadows, c. 500-900 m.

Scirpus atropurpureus Retzius, Observ. Bot. 5: 14. 1789

Scirpus atropurpureus Retz., Obs. Pl. 5: 14. 1789; E. lereschii Shuttlew., Flora 16: 241. 1837; Reichenb., Icon. Fl. Germ.8: Pl. 295, fig. 699. 1846. Blake in Proc. Roy. Soc. Queensland 50: Pl. 10, figs. 32-33. 1939.

atropurpurea: dark purple

Eleocharis atropurpurea (Retz.) Kunth, Enum. PI
2:151. 1837.
Scirpus atropurpureus Retz. Obs. 5 : 14. 1789.
Isolepis atropurpurea R. & S. Syst. Veg. 2 : 106. 1817.
Eleogiton atropurpurea A. Dietr. Sp. PL 2 : 97. 1833.
Eleogenus atropurpureus Nees in Wight, Contr. Bot. Ind. 113. 1834.
Eleocharis Lereschii Shuttl. Flora 20: 241. 1837. (Switzerland.)
Scirpus erraticvs Rota; De-Not. Ann. Sci. Nat. III. 5: 366. 1846. (Italy.)
Isolepis setifolia A. Rich. Tent. Fl. Abyss. 2: 498. 1852. (Abyssinia.)
Eleocharis Zanardinii Farl Fl. lta. 2: 67. 1852. (Italy.)
Eleocharis monandra Hochst. ; Steud. Syn. Cyp. 75. 1855. (Northern Africa.)
Isolepis allochroa Steud. Syn. Cyp. 91. 1855. (Bahia, Brazil.)
Isolepis dichroa Steud. Syn. Cyp. 91. 1855. (Senegal.)
Eleocharis ? erratica Steud. Syn. Cyp. 79. 1855. (Italy.)
Eleocharis multiflora Chapm. Fl. S. U. S. 517. 1860. (Florida.)
Trichophylhim atropurpureum House, Am. Midi. Nat. 6 : 204. 1920, 522 Dwarf annual, cespitose ; culms 3-12 cm. high, capillary, erect or arcuate ; sheaths deep brown at the base, the firm apex oblique and often attenuate ; spikelet oblong-ovoid, 2-8 mm. long, many-flowered, the lower scales frequently deciduous ; scales ovate, membranous, blunt, with' broad, green midrib and deep brown sides ; style bifid ; stamens 1-3 ; achenes strongly flattened, lenticular, obovoid, frequently widest at the summit, 0.5 mm. long, smooth, lustrousblack to translucent cherry-red; style-base minute, flattened, about one-fourth the width of the achene; bristles slender, translucent, shorter than the achene, often reduced or wanting.
Type locality: Calcutta, India {Koenig). .-,,,., -kt , , t ^ i j
Distribution : Sporadically in damp sand : Georgia, Florida, Nebraska, Iowa, Colorado, Washington (Lake Chelan), Texas; Mexico; tropics of the Old and New Worlds; Lake Leman, Switzerland; northern Italy. , ,„ ^, , t„ ^ r ,z j: ^ n a rat

Eleocharis atropurpurea is a species of spikesedge known by the common name purple spikerush. This is an aquatic plant native to much of (Africa, eastern and southern Asia, Australia, Latin America). It also has a wide distribution in temperate regions of North and South America and Asia. It is present in Europe, where it may be an introduced species for the most part.

Eleocharis atropurpurea can be found in wet areas from ocean shores to rice fields and irrigation ditches to inland lakes and rivers. This is an annual sedge rarely exceeding ten centimeters in height. It grows in tufts with few reddish-green leaves and many thin erect stems. Atop each stem is an oval-shaped, pointed inflorescence consisting of a spikelet under a centimeter long and containing at least ten flowers. Each tiny flower is covered by a bract which is a purplish-brown color. The fruit is a minute shiny black achene less than a millimeter long.