Jepson eFlora: Taxon page
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
Packera
GROUNDSEL, RAGWORT, BUTTERWEED

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.

Packera
Habit: Biennial or perennial herb 3--100+ cm from rhizome or taproot with thin branched fibrous roots, loosely hairy to glabrous. Stem: 1--several. Leaf: pinnate or generally simple, basal and proximal cauline generally petioled, mid sessile, reduced, distal bract-like. Inflorescence: heads discoid or radiate, in compact or open cyme-like clusters, rarely single; involucre generally bell-shaped (cylindric); main phyllaries generally 8, 13, or 21 in 1 series, reflexed in fruit, green to +- red, linear, glabrous or hairy, subtended by a few reduced outer phyllaries, not black-tipped; receptacle epaleate. Ray Flower: 0--13(21); corolla pale yellow to deep orange-red. Disk Flower: 20--80+; corolla bell-shaped to tubular, lobes 5 erect to recurved, generally yellow (to deep orange-red); style tips truncate. Fruit: cylindric, generally prominently ribbed, glabrous or stiff-hairy; pappus of white minutely barbed bristles.
Species In Genus: 64 species: North America, 1--2 in Siberia. Etymology: (J.G. Packer, Canadian botanist, b. 1929) Note: Formerly in Senecio. The common names groundsel, ragwort, and butterweed are applied to species of both Packera and Senecio.
eFlora Treatment Author: Debra K. Trock
Jepson Online Interchange
Key to Packera

Previous taxon: Osmadenia tenella
Next taxon: Packera bernardina

Name Search

Contact/Feedback

Citation for this treatment: Debra K. Trock 2016. Packera, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=69006, accessed on February 10, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on February 10, 2016.


Packera ionophylla
click for enlargement
© 2008 Thomas Stoughton
Packera neomexicana var. mutabilis
click for enlargement
© 2015 Barry Breckling
Packera cana
click for enlargement
© 2005 Steve Matson
Packera bolanderi var. bolanderi
click for enlargement
© 2014 Dana York
Packera breweri
click for enlargement
© 2005 Christopher L. Christie
Packera cana
click for enlargement
© 2005 Steve Matson

More photos of Packera in CalPhotos