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Dittrichia viscosa
FALSE YELLOWHEAD

Higher Taxonomy
Family: AsteraceaeView 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; Bahia in Hymenothrix; 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 Picradeniopsis; Trimorpha in Erigeron; Venidium in Arctotis; Whitneya in Arnica. Amauriopsis in TJM2 (2012) treated here in Hymenothrix; Arida in Leucosyris; Bahia in Picradeniopsis.
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: DittrichiaView DescriptionDichotomous Key

Habit: Annual or subshrub, sticky-glandular; odor strong, considered unpleasant by most people. Leaf: basal and cauline or cauline, alternate, sessile. Inflorescence: heads radiate, many, in dense raceme- or +- panicle-like clusters; involucre +- ovoid, +- bell-shaped when pressed; phyllaries graduated in 3--4 series, reflexed in fruit; receptacle flat, pitted, epaleate. Ray Flower: (6)10--18; corolla yellow, ray 3-lobed, not or barely or clearly exceeding phyllaries. Disk Flower: 9--14 or 25--40; corolla 4--5-lobed, yellow; anther base tailed, tip acute; style tips linear. Fruit: ellipsoid to +- cylindric, abruptly narrowed below pappus, glandular-hairy; pappus of barbed bristles, in 1 row, fused at base.
Species In Genus: 2 species: western Europe, Mediterranean, southwestern Asia; introduced, naturalized elsewhere. Etymology: (M. Dittrich, German student of Asteraceae, b. 1934) Note: Dittrichia viscosa added, as naturalized.
eFlora Treatment Author: Thomas J. Rosatti
Reference: Preston 2006 FNANM 19:473
Unabridged Reference: Brullo & De Marco 2000 Portugaliae Acta Biol 19:341--354

Dittrichia viscosa (L.) Greuter
NATURALIZED
Habit: Pl erect, 4--13 dm. Stem: generally 1--many, from near base, branched, woody. Leaf: cauline 4--6 cm, 6--13 mm wide, lanceolate to oblanceolate, teeth few--many on proximal, +- 0 on distal. Inflorescence: peduncle 7--12 mm; involucre 6--8 mm. Ray Flower: 12--18. Disk Flower: 25--40; corolla 6--7.5 mm. Fruit: +- 2 mm; pappus bristles 15--20, 4--6 mm. Chromosomes: 2n=18.
Ecology: roadsides, disturbed places, creeksides; Elevation: +- 43 m. Bioregional Distribution: CCo/ScV (sw of I-80/I-680 interchange), expected elsewhere; Distribution Outside California: native to Mediterranean Basin. Flowering Time: Sep--Nov Note: In North America, collected in ballast on east coast in late 1800s but then not again until 2014, in California, where it is reportedly scheduled for eradication; in Australia, on list of 28 most threatening non-native plants, even though considered only to be in early stages of establishment there.
Unabridged Note: In Australia, on the Alert List for Environmental Weeds, comprising "28 non-native plants that threaten biodiversity and cause other environmental damage", even though considered only to be in early stages of establishment there. In southwestern Western Australia: said to be spreading rapidly by seed along roadsides and walking trails in areas of medium to high rainfall; seed said to be spread by flotation (air or water) and also during soil movement (e.g. in road making or road grading, which also might have been the case in the California establishment) or when attached to machinery; and is said to be more reliant on moisture than Dittrichia graveolens, even having been collected from disturbed areas in swamps (http://www.environment.gov.au/cgi-bin/biodiversity/invasive/weeds/weeddetails.pl?taxon_id=7115).
eFlora Treatment Author: Thomas J. Rosatti
Reference: Preston 2006 FNANM 19:473
Unabridged Reference: Brullo & De Marco 2000 Portugaliae Acta Biol 19:341--354
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Citation for this treatment: Thomas J. Rosatti 2014, Dittrichia viscosa, in Jepson Flora Project (eds.) Jepson eFlora, Revision 2, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=2456, accessed on December 11, 2017.

Citation for the whole project: Jepson Flora Project (eds.) 2017, Jepson eFlora, http://ucjeps.berkeley.edu/eflora/, accessed on December 11, 2017.


Geographic subdivisions for Dittrichia viscosa:
CCo/ScV (sw of I-80/I-680 interchange), expected elsewhere;
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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Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.