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


Fallopia japonica
JAPANESE KNOTWEED


Higher Taxonomy
Family: PolygonaceaeView DescriptionDichotomous Key
Common Name: BUCKWHEAT FAMILY
Habit: Annual to shrub [tree]. Stem: nodes swollen or not. Leaf: simple, basal or cauline, generally alternate; ocreae present or 0, generally scarious, persistent or not. Inflorescence: flower clusters in axillary to terminal cyme-, panicle-, raceme-, spike-, umbel- or head-like arrangements, entire inflorescence or main inflorescence branches generally subtended by bracts ("inflorescence bracts"); peduncles present or 0; flower clusters in Eriogoneae-Eriogonoideae subtended by involucre of >= 1 free or +- fused, sometimes awn-tipped bracts ("involucre bracts") or, in Polygonoideae and rarely in Eriogonoideae, not (if bracts completely fused, involucre "tubular"); pedicels in Eriogoneae each often subtended by 2 free, transparent, linear bractlets or in Polygonoideae all subtended by 2+ fused, membranous, wide bractlets. Flower: generally bisexual, small, 1--200 per node; perianth parts 2--6, generally in 2 whorls, free or basally fused, generally petal-like, often +- concave adaxially, often darker at midvein, often turning +- red or +- brown in age; stamens [1]3 or 6--9 in 2 whorls; ovary superior, 1-chambered, ovule 1, styles 1--3. Fruit: achenes, included in or exserted from perianth, generally 3-angled, ovoid or elliptic, generally glabrous.
Genera In Family: 48 genera, +- 1200 species: worldwide, especially northern temperate; some cultivated for food (Coccoloba, sea-grape; Fagopyrum, Rheum, Rumex) or ornamental (Antigonon, lovechain; Coccoloba; Muehlenbeckia; Persicaria; Polygonum), a few timbered (Coccoloba; Triplaris). Several (Emex; Fallopia; Persicaria; Polygonum; Rumex) are weeds. Note: Treatment of genera in Eriogonoideae based on monographic work of James L. Reveal. Involucre number throughout is number (1--many) per ultimate grouping, at tips of ultimate branches; flower number is per flower cluster or involucre, unless otherwise stated. Fagopyrum esculentum Moench not naturalized, considered an historical waif (or garden weed +- presently), therefore not treated.
eFlora Treatment Author: Mihai Costea, except as noted
Scientific Editor: Thomas J. Rosatti, Bruce G. Baldwin.
Genus: FallopiaView DescriptionDichotomous Key


Habit: Annual, perennial herb, vine or not. Stem: erect, trailing, or twining, glabrous or hairy, ribs 0. Leaf: cauline, alternate, petioled; ocrea persistent or not, cylindric, papery, opaque; blade broad-ovate to triangular, entire. Inflorescence: axillary, terminal, spike-, panicle-, or raceme-like; flowers 3--7; peduncle present or 0. Flower: bisexual or pistillate (1 kind per pl); perianth generally enlarging, bell-shaped, pale green or white to pink, glabrous, base stalk-like, parts 5, fused basally or +- completely, of 2 kinds, outer 3 generally winged, > inner 2; stamens 6--8, filaments free, wider basally, glabrous or hairy, anthers yellow to pink or red, ovate to elliptic; styles 3, spreading, fused basally or +- completely, stigmas head-like, fringed, or peltate. Fruit: included or exserted, 3-angled, brown to black. Seed: embryo straight.
Species In Genus: 12 species: America, Europe, Asia, Africa. Etymology: (for Gabriele Fallopio, 1523--1562, Italian professor of anatomy, botany, and surgery, for whom Fallopian tubes also named)
eFlora Treatment Author: Mihai Costea
Fallopia japonica (Houtt.) Ronse Decr.
NATURALIZED
Habit: Perennial herb, rhizomed. Stem: generally in dense clumps, erect, generally 1--2 m, glaucous, glabrous, branches few. Leaf: ocrea 5--8 mm, +- brown, margin oblique, glabrous or puberulent; blade 6--13 cm, 5--10 cm wide, widely ovate, abaxially with 1-celled hairs < 0.1 mm on veins, adaxially glabrous, base truncate, tip acuminate. Inflorescence: axillary, generally distal, erect or spreading, panicle-like, 3--10 cm; peduncle 0--2.5 cm; pedicels 3--5 mm, glabrous; flowers 4--6. Flower: bisexual or functionally +- unisexual; perianth 4.5--6.5 mm, winged, +- white, glabrous, lobes obovate to elliptic, tips obtuse to acute; stamens 6--8, filaments glabrous; styles fused basally, stigmas fringed. Fruit: included, 3.8--5 mm, 2--2.2 mm wide, dark-brown, shiny, smooth. Chromosomes: 2n=44,88.
Ecology: Disturbed places; Elevation: < 1000 m. Bioregional Distribution: n CA-FP (esp s NCoR), SnFrB; Distribution Outside California: to eastern North America; native to Japan. Flowering Time: Aug--Oct Note: Introduced as ornamental, spreading aggressively.
Synonyms: Reynoutria japonica Houtt.; Polygonum cuspidatum Siebold & Zucc.; Tiniaria japonica (Houtt.) Hedberg
Jepson eFlora Author: Mihai Costea
Jepson Online Interchange
Noxious Weed listed by CDFA
Weed listed by Cal-IPC

Previous taxon: Fallopia convolvulus
Next taxon: Fallopia sachalinensis

Name Search

Botanical illustration including Fallopia japonica

botanical illustration including Fallopia japonica

Contact/Feedback

Citation for this treatment: Mihai Costea 2012, Fallopia japonica, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=82464, accessed on October 17, 2019.

Citation for the whole project: Jepson Flora Project (eds.) 2019, Jepson eFlora, http://ucjeps.berkeley.edu/eflora/, accessed on October 17, 2019.

Fallopia japonica
click for enlargement
© 2016 Keir Morse
Fallopia japonica
click for enlargement
© 2008 Keir Morse
Fallopia japonica
click for enlargement
© 2008 Keir Morse
Fallopia japonica
click for enlargement
© 2008 Keir Morse
Fallopia japonica
click for enlargement
© 2016 Keir Morse
Fallopia japonica
click for enlargement
© 2008 Keir Morse

More photos of Fallopia japonica in CalPhotos



Geographic subdivisions for Fallopia japonica:
n CA-FP (esp s NCoR), SnFrB
MAP CONTROLS
1. You can change the display of the base map and layers by clicking on the layer control box in the upper right-hand corner.
2. California county polygons can be turned off and on in the layer control box.
3. Filling of Jepson subdivision polygons can be turned off and on in the layer control box.
4. Moving the cursor over any numbered cluster will show the range boundary of the included specimens (with a blue polygon).
5. Marker clustering can be turned off by clicking this link:      Marker Clustering OFF
WARNING: Turning this off might cause maps with large numbers of specimens to load slowly.
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).





 

View elevation by latitude chart


Data provided by the participants of the  Consortium of California Herbaria.
MAP LEGEND
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.
READ ABOUT YELLOW FLAGS


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.