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Alternanthera philoxeroides

Higher Taxonomy
Family: AmaranthaceaeView DescriptionDichotomous Key

Habit: Annual to subshrub; monoecious and/or dioecious; occasionally spiny; hairs simple (branched). Leaf: blade simple, alternate or opposite, margins entire or serrate; veins pinnate; stipules 0. Inflorescence: axillary or terminal; 3-flowered cymes in dense spikes, heads or panicles; bracts 0 or 1--5, persistent; bractlets 0--2. Flower: bisexual or unisexual, small, green (+- white), yellow or purple; perianth parts 0 or (1)3--5, free or fused basally, scarious or hardened, persistent; stamens 1--5, opposite perianth parts, free or basally fused as a tube, generally unequal, occasionally alternate with appendages on stamen tubes (pseudostaminodes), anthers 2- or 4-chambered; ovary superior, chamber 1; ovule 1 (2--many); style (0)1--3, stigmas 1--3(5). Fruit: utricle; generally with persistent perianth or bracts. Seed: 1 [2+], small, lenticular to spheric, smooth or dotted to striate or tubercled.
Genera In Family: +- 75 genera, 900 species: cosmopolitan, especially disturbed, arid, saline or alkaline soils; some cultivated for food, ornamental; many naturalized, ruderal or agricultural weeds. Note: Amaranthaceae including Chenopodiaceae by some. Polycnemoideae, represented in California by Nitrophila, formerly considered subfamily of Chenopodiaceae, but needs further research. Guilleminea densa (Willd.) Moq. var. aggregata Uline & W.L. Bray is a waif. Froelichia gracilis (Hook.) Moq. is an historical waif.
eFlora Treatment Author: Mihai Costea, except as noted
Scientific Editor: Douglas H. Goldman, Bruce G. Baldwin.
Genus: AlternantheraView DescriptionDichotomous Key

Habit: [Annual] perennial herb, aquatic to terrestrial. Stem: prostrate or ascending; hairs simple. Leaf: opposite, subsessile to short-petioled, blade margins entire to serrate. Inflorescence: axillary or axillary and terminal, sessile or peduncled, many-flowered cylindric spikes or spheric heads; bracts and bractlets persistent, scarious. Flower: bisexual; perianth parts 5, free, +- equal or not, scarious, persistent, white, glabrous or woolly; stamens 3--5, fused at base into short tube or cup, anthers 2-chambered; pseudostaminodes 5, alternate with stamens; ovary obovoid to +- spheric; style short, +- 0.2 mm; stigma spheric (2-lobed), ovule 1, pendent. Fruit: indehiscent; fruit wall membranous. Seed: 1, lenticular or ovoid-oblong, +- red brown, smooth, shiny.
Species In Genus: +- 170 species: generally tropical America. Etymology: (Latin: alternating pseudostaminodes and stamens) Note: Alternanthera sessilis (L.) DC. occasionally a greenhouse weed ; Alternanthera ficoidea (L.) P. Beauv. var. bettzickiana (Regel) Backer widely cultivated, California reports unconfirmed.

Alternanthera philoxeroides (Mart.) Griseb.
Habit: Aquatic to semi-terrestrial, stoloniferous. Stem: prostrate, mat-forming, 50--120 cm, young stems and leaf axils white-hairy, in age +- glabrous or hairs in 2 lines. Leaf: petiole 2--10 mm; blade 30--130 mm, 5--35 mm wide, elliptic to obovate, glabrous or +- hairy near wedge-shaped base, tip obtuse or acute. Inflorescence: 1.2--1.7 cm diam, spheric; peduncle 1--9 cm; bract 2--2.5 mm, ovate to lanceolate, acute to acuminate, not keeled, glabrous. Flower: perianth parts 5--7 mm, +- equal, lanceolate or oblong, 1-veined, tip acute; stamens 5, filaments 2.5--3 mm, pseudostaminodes +- = stamens, oblong-linear; ovary obovoid. Fruit: unknown in North America. Chromosomes: 2n=100.
Ecology: Shallow water (< 2 m) or wet soils, marshes, edges of ponds; Elevation: < 200 m. Bioregional Distribution: SnJV, SCo; Distribution Outside California: to southeastern United States, Central America; native to South America. Flowering Time: May--Oct Note: Only vegetative reproduction in North America.
eFlora Treatment Author: Mihai Costea
Jepson Online Interchange
Noxious Weed

Previous taxon: Alternanthera caracasana
Next taxon: Amaranthus

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botanical illustration including Alternanthera philoxeroides


Citation for this treatment: Mihai Costea 2016. Alternanthera philoxeroides, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on May 04, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora,, accessed on May 04, 2016.

Geographic subdivisions for Alternanthera philoxeroides:
SnJV, SCo;
Markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.