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Ageratum mexicanum


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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Genus Ageratum

Annuals and perennials , mostly 20-120 cm. Stems often decumbent (rooting at proximal nodes), sparsely to densely branched. Leaves cauline; all or mostly opposite; petiolate ; blades mostly 1-nerved, deltate to ovate , or elliptic to lanceolate, margins entire or toothed , faces glabrous or ± pilose , puberulent , or strigoso-hispid, sometimes gland-dotted. Heads discoid , in dense to open, cymiform to corymbiform arrays. Involucres campanulate , 3-6 mm. Phyllaries persistent , 30-40 in 2-3 series, usually 2-nerved, lanceolate, ± equal (often indurate , margins scarious ). Receptacles conic, epaleate [paleate]. Florets 20-125; corollas white or bluish to lavender, throats ± campanulate (lengths 2 times diams.) ; styles: bases not enlarged, glabrous, branches ± linear to clavate (usually papillose and dilated distally). Cypselae prismatic , 4-5-ribbed, glabrous or sparsely strigoso-hispidulous; pappi persistent, of 5-6 aristate scales , or coroniform , or 0. x = 10.

Species ca. 40: United States, Mexico, Central America; 2 species widespread as adventives.[1]


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Ageratum Mexicanum


Publishing author : Sims Publication : Bot. Mag. t. 2524

Similar Species

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Members of the genus Ageratum

ZipcodeZoo has pages for 31 species, subspecies, varieties, forms, and cultivars in this genus:

A. aromaticum (Fragrant Ageratum) · A. conizoides (Mexican Ageratum) · A. conyzoides (Billy Goat Weed) · A. conyzoides houstonianum (Tropical Whiteweed) · A. conyzoides latifolium (Tropical Whiteweed) · A. corymbosum (Butterfly Mist) · A. houstonianum (Ageratum) · A. houstonianum 'Blue Bouquet' (Ageratum) · A. houstonianum 'Blue Danube' (Ageratum) · A. houstonianum 'Blue Fields' (Ageratum) · A. houstonianum 'Blue Horizon' (Ageratum) · A. houstonianum 'Blue Mink' (Floss Flower) · A. houstonianum 'Blue Puffs' (Blue Puffs Ageratum) · A. houstonianum 'Hawaii Blue' (Ageratum) · A. houstonianum 'Hawaii Royal' (Ageratum) · A. houstonianum 'Hawaii White' (Ageratum) · A. houstonianum 'Lohman's Frost' (Ageratum) · A. houstonianum 'Pacific' (Ageratum) · A. houstonianum 'Redtop' (Ageratum) · A. houstonianum 'Red Sea' (Ageratum) · A. houstonianum 'Southern Cross' (Ageratum) · A. houstonianum 'White Bouquet' (Ageratum) · A. lineare (Palafox) · A. littorale (Cape Sable Ageratum) · A. 'Alto Blue' (Floss Flower) · A. 'Artist Blue' (Artist Blue Ageratum) · A. 'Artist Blue Violet' (Floss Flower) · A. 'Artist Purple' (Ageratum) · A. 'Artist Rose' (Floss Flower) · A.'Hawaii Sky Blue' (Sky Blue Ageratum) · A. 'Island Mist' (Island Mist Ageratum)

More Info

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Further Reading

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  1. Guy L. Nesom "Ageratum". in Flora of North America Vol. 21 Page 460, 481. Oxford University Press. Online at [back]
Last Revised: 2014-05-09