Ageratum houstonianum Mill.,

Ageratum houstonianum Mill.,

FAMILY: ASTERACEAE
Morphological characters :

Habit: An erect annual hairy herb.

Stem: Erect, branched, hairy.

Leaves: Leaves simple, opposite, or the upper alternate, 1.2 – 2.2cm, exstipulate, petiolate, long, hairy, simple, ovate, sharply serrate, acute, base cuneate, unicostate reticulate venation.

Inflorescence: Dense terminal corymbose, homogamous capitula with all flowers tubular.

Flower: Bracteate involucral bracts linear, acute, green, ribbed on the bark with grey linings, pedicellate, complete, actinomorphic, bisexual, epigynous, Flowers blue with bad odour.

Calyx: Sepals 5, polysepalous, valvate, reduced to 5cm long, scaly structures, acuminate, 3mm long, bristled paleae.

Corolla: Petals 5, gamopetalous, valvate, tubular tube, 2.5mm with glistening sessile glands.

Androecium: Stamens 5, epipetalous, syngenesious, filaments short, anthers dithecous, basifixed, introrse.

Gynoecium: Bicarpellary, syncarpous, inferior ovary, unilocular with one ovule in the locule, basal placentation, style long, stigma bifid.

Fruit: 5- angled achene, 5mm long, pappus or 5 palaceous scales.

Flowering period: Throughout the year.

Fruiting period: Throughout the year.

Econimic importance: A. haustonianum is a more garden-worthy Plant than A. conyzoides, with large and more strongly coloured capitula.

Origin: Native of Mexico.