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, Doellingeria, 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; Viguiera in Aldama and Bahiopsis; Whitneya in Arnica. Amauriopsis in TJM2 (2012) treated here in Hymenothrix; Arida in Leucosyris; Bahia in Picradeniopsis; Eucephalus in Doellingeria.
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.

Common Name: THISTLE
Habit: Taprooted annual, biennial, or short-lived perennial herb that flowers once, or multi-flower perennial herb with taprooted rosettes arising from runner roots or from simple to branched caudex; glabrous to cobwebby or +- densely tomentose with long, fine, slender hairs, sometimes with thicker multicellular, jointed hairs that often appear crinkled, shining, iridescent when dry. Stem: generally erect. Leaf: basal and proximal cauline generally tapered or +- wing-petioled, generally wavy-margined, dentate to generally pinnately lobed and +- dentate, lobes and teeth spine-tipped, generally spiny-ciliate, faces glabrous to tomentose, especially abaxially; distal generally sessile, +- reduced. Inflorescence: heads discoid, 1--many, center head of cluster generally larger, generally erect; involucre +- cylindric to ovoid, spheric, or bell-shaped, persistent when dry; phyllaries many, graduated in 5--20 series, generally entire (spiny-ciliate or with irregularly toothed or cut scarious margin or distal appendage), outer and middle generally spine-tipped, in some species midrib with sticky-resinous ridge (milky when fresh, dark when dry, occasionally very narrow); inner phyllaries generally narrow, flat, tips straight or twisted; receptacle flat, long-bristly, epaleate. Flower: +- many, generally bisexual (unisexual in Cirsium arvense); corolla +- radial, white to red or purple, tube long, narrowly cylindric, throat cylindric, lobes linear; anther tube colored same as corolla or not, anther base sharply sagittate, tip linear or oblong; style generally exserted, tip cylindric, branches very short. Fruit: ovoid, thick or +- compressed, straw-colored or tan to dark brown, glabrous; attachment scar slightly angled; pappus bristles many, +- flattened proximally, plumose, weakly fused at base, often deciduous in ring, white to brown.
Etymology: (Greek: thistle) Note: Taxa difficult, variable, incompletely differentiated, hybridize. Exceptional white-flowered plants occur in most taxa with pigmented corollas; these generally not treated in key.
Unabridged Note: Native thistles are part of an apparently actively evolving group of species with many geog and ecological races and growth forms. Morphologically divergent species often are able to hybridize; unrecognized hybridization or intergradation often complicates identification. Stature, growth form, and proportions are subject to environmental influence.
eFlora Treatment Author: David J. Keil
Reference: Keil 2006 FNANM 19:95--164
Unabridged Reference: Kelch & Baldwin 2003 Molec Ecol 12:141--151

Common Name: SWAMP THISTLE
Habit: Biennial or perennial herb from taproot or woody caudex, 6--25 dm, gray-tomentose, hairs appressed, felt-like. Stem: 1--several, generally much-branched. Leaf: faces gray tomentose or becoming +- green adaxially; basal 3--11 dm, petiole spiny-toothed, blade coarsely dentate to deeply 1--2 × lobed and dentate, main spines 3--10 mm; cauline smaller, bases expanded to ear-like, spiny-winged, decurrent 1--3 cm, blade shallowly to deeply lobed, spines often 7--20 mm. Inflorescence: heads 10--many in +- leafy-bracted groups at branch tips, forming +- panicle-like cluster; peduncle (0)1--4(8) cm; involucre 1.5--2.5(3) cm, 2--4.5 cm diam, ovoid to hemispheric, generally dark green or +- purple; phyllaries graduated, ovate (outer) to lance-ovate (middle), tightly appressed, often with dark purple patch near tip, midrib with sticky-resinous ridge, outer and middle tipped by spreading spine 1--9 mm. Flower: corolla 18--21 mm, +- dark rose-purple (white), tube 8--9 mm, throat 5--6 mm, lobes 5--6 mm; style tips 3--4.5 mm. Fruit: 5--6 mm; pappus 15--20 mm.
Note: Some plants may not be readily assignable to variety. Closely related to Cirsium mohavense and Cirsium hydrophilum.