Jepson eFlora: Taxon page
Vascular Plants of California
Key to families | Table of families and genera
Previous taxon Index to accepted names and synonyms:
| A | B | C | D | E | F | G | H | I | J | K | L | M |
| N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Next taxon

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. possibly naturalized.
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.
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.
Jepson eFlora Author: Mihai Costea
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Noxious Weed listed on the CDFA Weed Pest Ratings table
View the CDFA Pest Rating page for Alternanthera philoxeroides
Weed listed by Cal-IPC

Previous taxon: Alternanthera caracasana
Next taxon: Amaranthus

Name Search

Botanical illustration including Alternanthera philoxeroides

botanical illustration including Alternanthera philoxeroides

Please use this Google Form for Contact/Feedback

Citation for this treatment: Mihai Costea 2012, Alternanthera philoxeroides, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on February 21, 2024.

Citation for the whole project: Jepson Flora Project (eds.) 2024, Jepson eFlora,, accessed on February 21, 2024.

No expert verified images found for Alternanthera philoxeroides.

Geographic subdivisions for Alternanthera philoxeroides:
1. You can change the display of the base map layer control box in the upper right-hand corner.
2. County and Jepson Region polygons can be turned off and on using the check boxes.
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).


Data provided by the participants of the  Consortium of California Herbaria.
View all CCH records
All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.

CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time (fruiting time in some monocot genera).