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Erigeron sumatrensis
TROPICAL HORSEWEED

Higher Taxonomy
Family: Asteraceae (Compositae)View DescriptionDichotomous Key

Common Name: SUNFLOWER FAMILY
Habit: Annual to tree. Leaf: basal and/or cauline, alternate, opposite, rarely whorled, simple to 2+ × compound. Inflorescence: 1° inflorescence a head, resembling a flower, of several types (see below), 1--many in generally +- cyme-like cluster; each head generally with +- calyx-like involucre of 1--many series of phyllaries (involucre bracts); receptacle of head flat to conic or columnar, paleate (bearing paleae = receptacle bracts) or epaleate; flowers 1--many per head. Flower: bisexual, unisexual, or sterile, +- small, of several types (see below); calyx 0 or modified into +- persistent pappus of bristles, scales, and/or awns; corolla radial or bilateral (0), lobes generally (0)3--5; stamens 4--5, filaments generally free, generally fused to corolla at tube/throat junction, anthers generally fused into cylinder around style, anther base generally rounded or cordate (deeply sagittate or with tail-like appendages), tip (= flattened appendage) generally projecting beyond pollen sac; pistil 1, 2-carpeled, ovary inferior, 1-chambered, 1-seeded, placenta basal, style 1, tip generally +- 2-branched (except in some staminate disk flowers), branch tips truncate or generally bearing +- brush-like appendages; stigmas 2, generally on adaxial faces of style branches. Fruit: achene (also called a cypsela) (drupe in Chrysanthemoides), cylindric to ovoid, sometimes compressed, generally deciduous with pappus attached.
Genera In Family: +- 1500 genera, 23000 species: worldwide, many habitats. Note: Flower and head types differ in form and sexual condition. A disk flower has a generally radial corolla, with a cylindric tube, expanded throat, and generally 5 lobes. Disk flowers are generally bisexual and fertile but occasionally staminate with reduced ovaries. Discoid heads comprise only disk flowers. A radiant head is a variant of a discoid head, with peripheral disk flower corollas expanded, often bilateral. A ray flower corolla is bilateral, generally with a slender tube and flattened petal-like ray (single lip composed of generally 3 lobes). Ray flowers are generally pistillate or sterile (occasionally lacking styles). Radiate heads have peripheral ray flowers and central disk flowers. Disciform heads superficially resemble discoid heads, with pistillate or sterile flowers that lack rays, together with or separate from disk flowers. A ligulate flower is bisexual, with a bilateral, generally ephemeral corolla and 5-lobed ligule. Liguliflorous heads comprise only ligulate flowers. See glossary p. 31 for illustrations of family characteristics. Echinops sphaerocephalus L., Gaillardia aristata Pursh, Gaillardia pulchella Foug., Hymenothrix loomisii S.F. Blake, Tagetes erecta L., Thelesperma megapotamicum (Spreng.) Kuntze are waifs. Melampodium perfoliatum Kunth, historic urban waif. Ageratum conyzoides L., Guizotia abyssinica (L. f.) Cass., Santolina chamaecyparisus L., orth. var. are rare or uncommon escapes from cultivation. Dyssodia papposa, Ismelia carinata (Schousb.) Sch. Bip. [Chrysanthemum carinatum Schousb.], Mantisalca salmantica (L.) Briq. & Cavill. are historical or extirpated waifs in California. Inula helenium L. not documented in California. Taxa of Aster in TJM (1993) treated here in Almutaster, Eucephalus, Eurybia, Ionactis, Oreostemma, Sericocarpus, Symphyotrichum; Chamomilla in Matricaria; Cnicus in Centaurea; Conyza in Erigeron and Laennecia; Dugaldia in Hymenoxys; Erechtites in Senecio; Hymenoclea in Ambrosia; Lembertia in Monolopia; Osteospermum ecklonis in Dimorphotheca; Picris echioides in Helminthotheca; Prionopsis in Grindelia; Raillardiopsis in Anisocarpus and Carlquistia; Schkuhria multiflora in Bahia; Trimorpha in Erigeron; Venidium in Arctotis; Whitneya in Arnica. Taxa of Arida in TJM2 (2012) treated here in Leucosyris.
Unabridged Note: Largest family of vascular plants in California and of eudicots globally.
eFlora Treatment Author: David J. Keil, except as noted
Scientific Editor: David J. Keil, Bruce G. Baldwin.
Genus: ErigeronView DescriptionDichotomous Key

Common Name: FLEABANE DAISY
Habit: Annual to perennial herb (subshrub). Stem: generally erect. Leaf: alternate, generally sessile, generally entire (toothed or lobed to ternately dissected). Inflorescence: heads generally radiate (discoid, disciform), 1--few (many), peduncled; inflorescence generally +- flat-topped (raceme- to panicle-like); involucre urn- to bell-shaped or generally hemispheric; phyllaries linear to narrowly lanceolate, in 2--several series, +- equal to strongly graduated, generally ascending or erect in flower, generally green, spreading when pressed, reflexed when dry; receptacle flat to steeply conic, smooth to shallowly pitted, epaleate. Ray Or Pistillate Flower: (0)10--generally many; ray generally narrow, generally white or pink to lavender or blue-purple (yellow), generally spreading when fresh, often coiled or reflexed when dry. Pistillate Flower: (0)10--generally many; ray generally narrow, generally white or pink to lavender or blue-purple (yellow), generally spreading when fresh, often coiled or reflexed when dry. Disk Flower: generally many; corolla generally narrowly funnel-shaped, yellow; anther tip +- lanceolate; style tips 0.1--0.8 mm, +- triangular. Fruit: generally 0.5--3 mm, generally +- oblong, compressed to +- cylindric, generally 2-ribbed, generally sparsely hairy; pappus (0) generally double, outer of short bristles, narrow scales, or a short crown, inner of 6--50 long bristles.
Species In Genus: +- 375 species: worldwide. Etymology: (Greek: early old age) Note: Erigeron concinnus (Hook. & Arn.) Torr. & A. Gray var. condensatus D.C. Eaton, Erigeron disparipilus Cronquist, and Erigeron lobata A. Nelson apparently not in California.
eFlora Treatment Author: David J. Keil & Guy L. Nesom

Erigeron sumatrensis Retz.
NATURALIZED
Habit: Annual 30--200+ cm. Stem: erect, leafy, branched distally or throughout, puberulent or long-soft-hairy to bristly, hairs +- ascending; central stem generally exceeding branches. Leaf: margin +- fine-strigose, faces +- glabrous to puberulent, densely strigose, or bristly, hairs +- erect on veins; basal and proximal cauline 5--10 cm, 5--20 mm wide, +- petioled, linear to elliptic or oblanceolate, entire or toothed, generally withered by flowering; distal similar, sessile, smaller, generally entire. Inflorescence: heads disciform, many in panicle-like to +- flat-topped clusters; involucre 4--5 mm, 3--4 mm diam, +- urn-shaped in flower; phyllaries weakly graduated, +- glabrous to puberulent, densely strigose, or spreading-hairy, green when fresh, central part of middle phyllaries generally wider than lighter margin, not red-brown or resin filled when dry; receptacle 1--2.5 mm diam in fruit. Pistillate Flower: 60--90+; ray 0--0.3 mm, white or cream. Disk Flower: 6--10. Fruit: 1--1.5 mm, pale tan (generally some with +- red ribs), sparsely minutely strigose or +- glabrous; pappus bristles 15--25, 3--4 mm, cream to tan.
Ecology: Disturbed sites; Elevation: < 600+ m. Bioregional Distribution: NW (exc NCoRH), CaRF, n SNF, ScV, CW (exc SCoRI), SCo, ChI, PR (exc SnJt); Distribution Outside California: widely naturalized; native to South America. Flowering Time: All year
Synonyms: Conyza sumatrensis (Retz.) E. Walker; Conyza floribunda Kunth; Conyza bilbaoana J. Rémy, misappl.
Unabridged Note: Pruski & Sancho 2006 Novon 16:96--101 distinguished two varieties of Conyza sumatrensis. Herbage and phyllaries of var. sumatrensis are +- densely hairy with soft to stiff appressed to spreading hairs. Leaves and stems of var. leiotheca (S.F. Blake) Pruski & G. Sancho are +- glabrous to sparsely hairy, and phyllaries are glabrous or rarely weakly puberulent. Some California plants approach var. leiotheca. Varietal names for these taxa have not been published in Erigeron, and ranges of the forms in California are not distinguished here.
eFlora Treatment Author: David J. Keil & Guy L. Nesom
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Citation for this treatment: David J. Keil & Guy L. Nesom 2016. Erigeron sumatrensis, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=91898, accessed on May 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 27, 2016.


Erigeron sumatrensis
click for enlargement
© 2006 Michael Charters
Erigeron sumatrensis
click for enlargement
© 2006 Michael Charters
Erigeron sumatrensis
click for enlargement
© 2006 Michael Charters
Erigeron sumatrensis
click for enlargement
© 2006 Michael Charters

More photos of Erigeron sumatrensis in CalPhotos


Geographic subdivisions for Erigeron sumatrensis:
NW (exc NCoRH), CaRF, n SNF, ScV, CW (exc SCoRI), SCo, ChI, PR (exc SnJt);
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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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.