Ageratum conyzoides

Linnaeus

Sp. Pl. 2: 839. 1753.

Common names: Tropical whiteweed
Introduced
Synonyms: Ageratum latifolium Cavanilles
Treatment appears in FNA Volume 21. Treatment on page 482. Mentioned on page 483.

Annuals, perennials, or subshrubs, 20–150 cm (fibrous-rooted). Stems erect, sparsely to densely villous. Leaf-blades ovate to elliptic-oblong, 2–8 × 1–5 cm, margins toothed, abaxial faces sparsely pilose and glanddotted. Peduncles minutely puberulent and sparsely to densely pilose, eglandular. Involucres 3–3.5 × 4–5 mm. Phyllaries oblong-lanceolate (0.8–1.2 mm wide), glabrous or sparsely pilose (margins often ciliate), eglandular, tips abruptly tapering, subulate, 0.5–1 mm. Corollas usually blue to lavender, sometimes white. Cypselae sparsely strigoso-hispidulous; pappi usually of scales 0.5–1.5 (–3) mm, sometimes with tapering setae, rarely 0.2n = 20, 40.


Phenology: Flowering Jul–Aug.
Habitat: Disturbed sites, mostly coastal
Elevation: 0–20 m

Distribution

V21-1212-distribution-map.gif

Introduced; Ala., Calif., Conn., Fla., Ga., Ky., Md., Miss., Mo., N.C., South America, Mexico, West Indies, Central America, Pacific Islands (Hawaii)

Discussion

Ageratum conyzoides is apparently native to South America. North American plants were escapes and naturalized from cultivation.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Ageratum conyzoides"
not tailed +, truncate +, rounded +  and obtuse +
scarious +
usually ovate +  and lanceolate +
usually terete +  and clavate +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
Guy L. Nesom +
Linnaeus +
decurrent +
not enlarged +
dissected +, lobed +, toothed +  and entire +
deltate;ovate or elliptic +
papillate +  and rugose +
(4-)5-angled;10-ribbed +
less linear;clavate +
Tropical whiteweed +
white +, usually blue +  and lavender +
strigoso-hispidulous +
prismatic +
fertile +  and bisexual +
Ala. +, Calif. +, Conn. +, Fla. +, Ga. +, Ky. +, Md. +, Miss. +, Mo. +, N.C. +, South America +, Mexico +, West Indies +, Central America +  and Pacific Islands (Hawaii) +
0–20 m +
strigoso-hispid +, puberulent +, pilose +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Disturbed sites, mostly coastal +
cymiform +  and corymbiform +
in usually determinate , rarely indeterminate , arrays +  and singly +
indeterminate +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
campanulate +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
2 cm20 mm <br />0.02 m <br /> (8 cm80 mm <br />0.08 m <br />) +
1 cm10 mm <br />0.01 m <br /> (5 cm50 mm <br />0.05 m <br />) +
lanceolate +  and lance-linear +
2-carpellate +
persistent +
coroniform +
pilose +  and puberulent +
Flowering Jul–Aug. +
pilose +  and glabrous +
30 +  and 40 +
subequal +  and unequal +
bearing subulate enations +, hairy +  and bristly +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
5 +  and 6 +
aristate +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
exalbuminous +
tapering +
Introduced +
appendaged +  and truncate +
hirsutulous +
papillate +
Ageratum latifolium +
Ageratum conyzoides +
Ageratum +
species +
campanulate +
subulate +  and tapering +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
perennial +  and annual +
20 cm200 mm <br />0.2 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +