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Gamochaeta
CUDWEED

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.

Gamochaeta
Habit: Annual to short-lived perennial herb; taprooted or fibrous-rooted. Stem: erect to +- ascending. Leaf: basal and cauline, +- sessile, linear to oblanceolate or spoon-shaped, entire, base tapered to +- cordate, generally +- densely tomentose. Inflorescence: heads disciform, generally in tight groups in generally spike- or panicle-like clusters, reduced to terminal cluster in small plants; involucre cylindric to +- urn-shaped, +- bell-shaped when pressed; phyllaries graduated in 3--7 series, bases stiff-papery to scarious, margins and tips transparent-membranous, often shiny, generally +- brown to straw-colored; receptacle flat, concave in fruit, smooth, epaleate. Pistillate Flower: pistillate 50--130; corolla narrowly tubular, yellow or distally +- purple to purple- to yellow-brown. Disk Flower: 2--7; corolla yellow or distally +- purple or purple- to yellow-brown; anther tip triangular; style tips truncate, hair-tufted. Fruit: oblong, slightly flattened, faces papillate; pappus bristles in 1 series, basally fused, deciduous in ring.
Species In Genus: +- 50 species: native to America, some species widely naturalized. Etymology: (Greek: united hair, for pappus bristles)
eFlora Treatment Author: Guy L. Nesom & Thomas J. Rosatti
Jepson Online Interchange
Key to Gamochaeta

Previous taxon: Galinsoga parviflora var. parviflora
Next taxon: Gamochaeta argyrinea

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Citation for this treatment: Guy L. Nesom & Thomas J. Rosatti 2016. Gamochaeta, Revision 1, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=444, accessed on February 08, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on February 08, 2016.


Gamochaeta purpurea
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© 2010 Gary A. Monroe
Gamochaeta purpurea
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© 2010 Gary A. Monroe
Gamochaeta ustulata
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© 2008 Neal Kramer
Gamochaeta ustulata
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© 2006 Steve Matson
Gamochaeta ustulata
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© 2007 Neal Kramer
Gamochaeta ustulata
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© 2008 Keir Morse

More photos of Gamochaeta in CalPhotos