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Vascular Plants of California
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Arctotheca calendula

Higher Taxonomy
Family: Asteraceae (Compositae)View DescriptionDichotomous Key
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: ArctothecaView DescriptionDichotomous Key

Habit: Annual or perennial herb, +- glandular and/or with segmented hairs. Stem: 0, or prostrate and creeping with adventitious roots at nodes, or shortly decumbent to erect, ribbed, white-cobwebby. Leaf: alternate, basal in rosettes and/or cauline, petioled, (2)5--20(30+) cm, (1)2--5(7) cm wide, [ovate] obovate to spoon-shaped, +- deeply pinnately lobed, ultimate margin +- dentate-prickly [entire or shallowly toothed] or distal +- entire, adaxially finely cobwebby [densely woolly], abaxially densely white-woolly. Inflorescence: heads radiate, 1, peduncled; phyllaries graduated in 3--6 series, proximal narrowed to spreading or reflexed, awn-like, tips fringed, distal with expanded membranous tips; receptacle flat, +- pitted, pit margins with short, membranous scales, epaleate. Ray Flower: sterile; ray adaxially yellow throughout or with +- deeper yellow proximal band (dried rays yellow or proximally +- white with distal blue margin and distally blue to +- brown-purple), abaxially yellow to +- blue, red, or purple; style 0. Disk Flower: corolla yellow throughout, or distally +- green to +- black; anther tip ovate-triangular; style tip proximally slender, thickened distal to a minutely hairy node, branches minute. Fruit: obovoid-elliptic, compressed, 4--5-ribbed, faces roughened, woolly to +- glabrous, occasionally with proximal cluster of segmented hairs; pappus of [2--3] 6--10 scales < fruit, crown-like, or 0.
Species In Genus: 5 species: native southern Africa. Etymology: (Greek: bear-capsule, probably for woolly fruit)
eFlora Treatment Author: Alison M. Mahoney & Robert J. McKenzie
Reference: Mahoney 2006 FNANM 19:197
Unabridged Reference: McKenzie et al. 2005 Ann Missouri Bot Gard 92:569--594
Arctotheca calendula (L.) Levyns
Leaf: rosette and proximal cauline leaves +- 0 on older pls. Inflorescence: heads 2--4(5.5) cm diam. Ray Flower: 6--13(17); ray 2--3(4) mm wide, adaxially uniformly pale yellow or with darker yellow proximal band, abaxially steely blue. Fruit: +- 3 mm, densely +- purple- to brown-woolly; pappus scales 6--9 or 0, generally obscured by hairs. Chromosomes: 2n=18.
Ecology: Disturbed coastal areas; Elevation: < 100 m. Bioregional Distribution: NCo, CCo, SCoRO; Distribution Outside California: +- suitable habitats worldwide. Flowering Time: Mar--Aug Note: Highly invasive, still uncommon in California.
Jepson eFlora Author: Alison M. Mahoney & Robert J. McKenzie
Reference: Mahoney 2006 FNANM 19:197
Index of California Plant Names (ICPN; linked via the Jepson Online Interchange)
Noxious Weed listed by CDFA
Weed listed by Cal-IPC

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Botanical illustration including Arctotheca calendula

botanical illustration including Arctotheca calendula


Citation for this treatment: Alison M. Mahoney & Robert J. McKenzie 2012, Arctotheca calendula, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on December 11, 2019.

Citation for the whole project: Jepson Flora Project (eds.) 2019, Jepson eFlora,, accessed on December 11, 2019.

No expert verified images found for Arctotheca calendula.

Geographic subdivisions for Arctotheca calendula:
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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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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.
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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.