Cyanthillium cinereum |
Asteraceae tribe Vernonieae |
|||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
little ironweed |
|
|||||||||||||||||||||
Habit | Annuals, biennials, perennials, or shrubs [trees or lianas] (sap rarely milky). | |||||||||||||||||||||
Leaves | blades 20–35(–50+) × 12–25(–30+) mm (including petioles). |
usually cauline, sometimes basal or basal and cauline; alternate (rarely subopposite distally) [opposite]; usually petiolate, sometimes sessile (or petioles winged); margins usually ± dentate, sometimes entire [lobed or dissected]. |
||||||||||||||||||||
Bracts | ± linear at proximal nodes, wanting distally. |
|||||||||||||||||||||
Peduncles | 3–10(–20+) mm. |
|||||||||||||||||||||
Receptacles | flat to convex, usually epaleate (often foveolate, sometimes setose). |
|||||||||||||||||||||
Ray florets | 0 (corollas of peripheral florets enlarged, zygomorphic, ± raylike in Stokesia). |
|||||||||||||||||||||
Disc florets | bisexual, fertile; corollas white, ochroleucous, or pink to cyanic [yellow]; anther bases ± sagittate [tailed], apical appendages ovate to lanceolate; styles abaxially hirsutulous (at least distally), branches lance-linear to ± lanceolate, adaxially continuously stigmatic from bases nearly to apices, apices acute, appendages essentially none. |
|||||||||||||||||||||
Phyllaries | 3–4 mm. |
usually persistent [readily falling], in 2–8+ series, distinct, unequal, herbaceous to chartaceous, margins and/or apices sometimes scarious. |
||||||||||||||||||||
Calyculi | 0. |
|||||||||||||||||||||
Heads | homogamous (discoid, pseudo-radiant or -liguliflorous in Stokesia), usually in corymbiform, paniculiform, or scorpioid arrays, sometimes borne singly or in glomerules [aggregated in second-order heads]. |
|||||||||||||||||||||
Cypselae | 1.5–2 mm; pappi white, outer scales 0.1–0.3 mm, inner bristles 3–4 mm. |
± monomorphic within heads, columnar to clavate, fusiform, or prismatic, sometimes compressed, not beaked, bodies smooth, nerved, or ribbed (glabrous or hirsutulous to strigillose, sometimes resin-gland-dotted as well); pappi usually persistent, usually in 2 series (outer series of shorter, stouter bristles or narrow scales, inner of longer, usually barbellate bristles), sometimes in 1 series (bristles or scales, scales often aristate). |
||||||||||||||||||||
2n | = 36. |
|||||||||||||||||||||
Cyanthillium cinereum |
Asteraceae tribe Vernonieae |
|||||||||||||||||||||
Phenology | Flowering year-round. | |||||||||||||||||||||
Habitat | Disturbed places | |||||||||||||||||||||
Elevation | 0–10 m (0–0 ft) | |||||||||||||||||||||
Distribution |
FL; Mexico; Central America; South America; West Indies; Asia; Africa; Indian Ocean Islands; Pacific Islands [Introduced in North America] |
Mostly tropics and warm-temperate regions of New World and Old World |
||||||||||||||||||||
Discussion | Genera 100–140, species ca. 1300 (6 genera, 25 species in the flora). Most members of Vernonieae are herbs, subshrubs, or shrubs (Vernonia arborea Buchanan-Hamilton of tropical Asia may form trees to 33 m). They are characterized by discoid heads of bisexual florets with purple to pink or white corollas, calcarate anthers, attenuate, abaxially hirsutulous style branches stigmatic ± uniformly (rather than in two lines or bands) nearly to their tips, and pollen grains with regular, polygonal, patterns of ± spiny to smooth ridges. Centers of species concentration for the tribe are found in Africa, Madagascar, South America, and Antilles. In the flora, most species are found in the eastern and southern states of the United States. The plants are often associated with open, prairie or savanna-like areas. Treating clades recognized by J. L. Panero and V. A. Funk (2002) as corresponding to tribes, Vernonieae is sister to Liabeae (none in the flora) and is included with Arctotideae (introduced), Cichorieae, and Gundelieae (none in the flora) within Cichorioideae. Historically, 80% or so of the species in the tribe were included in Vernonia. H. Robinson (1999) has argued for resurrections and recircumscriptions of some old genera and recognition of some “new” genera, resulting in a Vernonia of ca. 20 species. Stokesia laevis and some Vernonia species are grown as ornamentals. Some Vernonia species have been used medicinally in folk remedies and some may be locally troublesome as weeds (e.g., V. baldwinii). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|||||||||||||||||||||
Key |
|
|||||||||||||||||||||
Source | FNA vol. 19, p. 205. | FNA vol. 19, p. 200. | ||||||||||||||||||||
Parent taxa | Asteraceae > tribe Vernonieae > Cyanthillium | Asteraceae | ||||||||||||||||||||
Subordinate taxa | ||||||||||||||||||||||
Synonyms | Conyza cinerea, Vernonia cinerea | |||||||||||||||||||||
Name authority | (Linnaeus) H. Robinson: Proc. Biol. Soc. Wash. 103: 252. (1990) | Cassini: J. Phys. Chim. Hist. Nat. Arts 88: 203. (1819) | ||||||||||||||||||||
Web links |