Asteraceae Dumortier
Daisy family.
Asteraceae (Compositae), daisy family.
Vegetative morphology. Plants dwarf shrubs, or low shrubs (rarely, i.e. Senecio congestus and Tripleurospeumum maritimum), or mid shrubs; 2–30(–60) cm high; flowering with one or more capitulate inflorescences. Taproot present, or absent. Caudex present, or absent. Ground-level or under-ground stems horizontal, or vertical and often branched; rhizomatous, or stoloniferous; elongate, or compact; 0.5–10 mm wide. Vegetative, aerial, stem a small transition zone between roots and basal leaves, or vegetative stem a small transition zone between roots and branches arising at ground-level, or aerial stems developed; aerial stems erect, or ascending; aerial stems glabrous, or sparsely hairy, or densely hairy; aerial stem hairs appressed, or spreading, or erect. Leaves in a basal tuft and distributed along the stems, or basal in a rosette. Leaves patent, or erect. Leaves alternate, or opposite (Arnica); existing for a single season or less, or marcescent. Stipules absent. Petioles present, or absent; 0–80(–100) mm long; winged, or unwinged; flat; glabrous, or hairy, or glabrescent; pubescent, or pilose, or villous, or tomentose, or woolly, or hairs long-silky; hairs less than the diameter of the petiole, or hairs more than the diameter of the petiole. Petioles hairs appressed, or spreading, or erect; straight, or floccose, or curved, or wavy; smooth. Leaf blade bases truncate, or obtuse, or attenuate, or rounded. Blades 2–120 mm long; 1–30(–70) mm wide. Blades spreading, or divaricate; herbaceous; straight; linear, or lanceolate, or oblanceolate, or obovate, or spatulate; flat; veins pinnate, or veins palmate, or appearing single-veined, or with inconspicuous veins. Blades adaxial surface with sessile glands (rarely), or without sessile glands; glabrous, or glabrescent, or hairy. Blades adaxial surface hairs pubescent, or pilose, or villous, or woolly, or long-silky; simple, unbranched (and), or glandular; sparse, or moderately dense, or dense (if applicable); white and translucent, or grey, or a mixture of white and yellow hairs, or multicellular with deep purple pigment at the cell end walls, or tawny. Blades abaxial surface glabrous, or glabrescent, or hairy. Blades abaxial surface hairs sparse, or moderately dense, or very dense (often sparse near the base of the flowering stem and dense near the flowering head). Blades abaxial surface puberulent, or pilose, or villous, or tomentose, or hairs woolly, or hairs short-silky, or hairs long-silky. Blades abaxial surface hairs white, or translucent hairs, or rust-colored hairs, or a mixture of white and yellow hairs; straight, or curved, or wavy; appressed, or spreading, or erect. Blade margins lobed, or not lobed, or cut into linear divisions. Blade margins entire, or glandular-dotted, or serrulate, or serrate, or crenate, or dentate, or deeply divided, or runcinate; glabrous, or with non-glandular hairs, or with glandular hairs; degree of incision 5–95 %. Leaf apices acuminate, or acute, or obtuse, or rounded, or mucronate. Leaflets veins inconspicuous. Apical leaflet base not distinctly stipitate (if applicable).
Reproductive morphology. Plants dioecious, or bisexual, or agamospermic. Flowering stems present. Flowering stems with leaves, or without leaves; glabrous, or hairy. Flowering stem hairs pilose, or villous, or tomentose, or woolly; simple and glandular (sometimes); shorter than the diameter of the flowering stem, or longer than the diameter of the flowering stem; white or translucent, or brown, or transparent with deep purple cross-walls. Inflorescence a solitary head, or of several flowering heads; terminal, or axillary; ovate, or globose or subglobose, or obovate, or ellipsoid; 0.7–15(–20) cm long; 10–160 mm wide. Capitula 3–15(–30) mm deep. Capitula 2.5–60 mm wide. Pedicels absent, or subtending flowering heads; glabrous, or with non-glandular hairs. Involucral bracts present; number of rows 1–3(–5). Outer involucral bracts blade surface flat, or blades cut into linear divisions; mostly green, or mostly red or purple pigmented, or outermost bracts green, sometimes with red pigment in centre; innermost bracts frequently purple or occasionally green, or outermost bracts green, with brown or red edges; innermost bracts almost transparent with red or brown central area, or with a green central portion and wide dark margins, or with silvery grey central area and wide brown margins; strongly reflexed, or lying adjacent to the flowers, or spreading to erect; linear, or oblong, or lanceolate, or ovate; glabrous, or sparsely hairy, or densely hairy; with glandular hairs, or hairs non-glandular; 1.5–10(–15) mm high; 0.5–3 mm wide. Inner involucral bracts apex prominently horned, or sometimes callose, but without a prominent horn, or with or without horns or calloses, or entire, or lacerate; oblong, or lanceolate, or ovate, or obovate; margins wide, scarious for at least one quarter of the bract, or at the most with narrow and scarious, less than one quarter of the bract; 2.5–20 mm high; 0.4–3.5 mm wide. With only disc florets, or with only ray florets, or with ray and disc florets. Flowers actinomorphic, or zygomorphic. Perianth present, or with a single whorl of petals. Calyx modified to a pappus (usually), or absent, or present (remnant). Calyx accrescent, or non-accrescent. Pappus with a single row of hairs, or with a double row of hairs. Pappus yellowish (rarely), or whitish. Ray floret pappus 2.8–12(–15) mm long. Disc floret pappus 3.3–8(–12) mm long. Petals present; fused; longer than the calyx (usually); 5; white, or yellow, or red, or pink, or purple, or brown; with contrasting markings, or without contrasting markings; 1–11(–13) mm long. Corolla tubular, or funnel-form, or ligulate; unlobed, or 3-lobed, or 5-lobed (lobes sometimes poorly defined in ray florets). Ray florets 3–130. Ray florets limb 4–20(–30) mm long; 0.5–2(–4) mm wide. Flowers unisexual, or bisexual (or a mixture of both). Stamens 5 (usually); filaments all equal in length; free of the corolla (the anthers are connivent into a tube, but not attached to the corolla). Anthers yellow (usually), or purple (Saussurea); slender-cylindrical (if applicable); 0.9–2.6 mm long. Gynoecia inferior. Carpels syncarpous; 2. Styles 1; completely fused (the terminal portion of the style dividing into two long or short stigmatic branches); 1.5–12(–16) mm long. Stigmas per style 2; broad-cylindrical (sometimes when receptive), or strap-like lobes. Placentation basal. Ovules 1. Fruit sessile. Fruit with calyx persisting; dry; cypselas; elongate-cylindrical, or obovate, or oblong, or clavate, or urceolate; indehiscent. Fruit 1–5.5 mm long; 0.3–1.2 mm wide; yellowish, or black, or brown, or red, or straw coloured; surface appearing veinless, or venation ribbed. Seeds 1.
Chromosome information. 2n = 14, 18, 36, 42, 54, 60, 63, 84, 90. Packer (1972), Löve and Löve (1975).
Illustrations. • Asteraceae: ray and disc florets.. Flowers clustered in a capitulum, a flowering head composed in this case of ray florets and disc florets. • Asteraceae: ligulate flowers only. Close-up of capitulum inflorescence composed only of ligulate or ray flowers. • Asteraceae: disc florets only. Flowering head, capitulum composed only of white disc florets that have stigmas exposed.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
