Oncosiphon

Källersjö

Bot. J. Linn. Soc. 96: 310, figs. 2F, 6, 16E1, 16E2. 1988.

Etymology: Greek onkos, swelling, and siphon, tube allusion unclear
Treatment appears in FNA Volume 19. Treatment on page 539. Mentioned on page 53, 487.
 TaxonIllustrator 
FNA19 P63 Oncosiphon piluliferum.jpegOncosiphon piluliferum
Matricaria occidentalis
Pentzia incana
John Myers
Yevonn Wilson-Ramsey
John Myers

Annuals, 5–15 (–50+) cm (usually strongly scented). Stems 1–5+ from bases, erect to ascending, branched ± throughout, ± puberulent or sparsely strigillose (hairs basifixed) and gland-dotted [glabrous]. Leaves mostly cauline; alternate; petiolate or sessile; blades ovate to obovate [linear], usually [1–] 2 (–3) -pinnately lobed, ultimate margins entire, faces ± puberulent or sparsely strigillose and gland-dotted [glabrous]. Heads discoid [radiate], borne singly or in corymbiform arrays (pedunculate). Involucres ± hemispheric or broader [cylindric], [3–] 4–6 [–8+] mm diam. Phyllaries persistent or tardily falling (± reflexed in fruit), [15–] 22–35 [–60+] in 3–4+ series, distinct, lance-triangular to ± ovate or elliptic (± navicular, carinate, sometimes each with central resin canal), unequal, margins and apices scarious. Receptacles [± flat] hemispheric, ± globose, or conic, epaleate (often muricate). Ray-florets 0 [to 10, pistillate, fertile; corollas white, laminae ± obovate]. Disc-florets [20–] 100–250+, bisexual, fertile; corollas yellow, tubes ± cylindric (often basally invaginated and ± decurrent onto ovaries; tubes and proximal portions of throats externally continuous and ± dilated with relatively large, quadrate cells, often oblique, fragile when dry, distally constricted and texturally distinct from ± campanulate distal portions of throats), lobes 4, triangular. Cypselae columnar to prismatic (proximally tapered), ribs 4, faces gland-dotted between ribs, especially adaxially (pericarps without myxogenic cells or resin sacs; embryo-sac development monosporic); pappi coroniform (shorter adaxially), dentate or entire. x = 6, 8.

Distribution

Introduced; s Africa, also in Australia

Discussion

Species 8 (1 in the flora).

Oncosiphon suffruticosum (Linnaeus) Källersjö [Matricaria suffruticosa (Linnaeus) Druce] was collected on ballast at Portland, Oregon, in 1902. It differs from O. piluliferum by smaller (3–5 mm diam.) heads clustered in dense, ± flat-topped, corymbiform arrays. Both O. piluliferum and O. suffruticosum are common weeds in their native southern Africa and in Australia. Both have the potential to become serious pests in western North America. They are unpalatable to livestock and tend to dominate infested pasturelands. When consumed by animals, they taint the flavor of milk and meat.

"broader" is not a number.

... more about "Oncosiphon"
not tailed +  and obtuse +
scarious +
indeterminate +  and determinate +
David J. Keil +
Källersjö +
decurrent +
compound +  and simple +
lobed;ovate;obovate +
zygomorphic +, actinomorphic +  and (3-)5-merous +
winged +  and monomorphic +
columnar +  and prismatic +
fertile +  and bisexual +
fertile +  and bisexual +
s Africa +  and also in Australia +
Greek onkos, swelling, and siphon, tube +  and allusion unclear +
gland-dotted;gland-dotted +
strigillose +  and puberulent +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
in corymbiform arrays +  and singly +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
hemispheric +
sessile +  and petiolate +
triangular +
entire +  and dentate +
2-carpellate +
entire +  and dentate +
persistent +
coroniform +
22 +  and 35 +
Bot. J. Linn. Soc. +
styliferous +, neuter +  and pistillate +
sterile +  and fertile +
bearing subulate enations +, hairy +  and bristly +
conic;globose;conic;globose;hemispheric +
kallersjo1988a +
exalbuminous +
gland-dotted +
erect +  and ascending +
strigillose +  and puberulent +
1 +  and 5 +
appendaged +  and truncate +
papillate +
Compositae +
Oncosiphon +
Asteraceae tribe Anthemideae +
cylindric +
15 cm150 mm <br />0.15 m <br /> (50 cm500 mm <br />0.5 m <br />) +
5 cm50 mm <br />0.05 m <br /> (15 cm150 mm <br />0.15 m <br />) +
shrub +  and subshrub +