Tridax procumbens Linn.
Locally known as wild daisy, tridax, coat button (English). It flowers throughout the year, from January to December. Commonly found as a weed in open places.
An annual or perennial herb. Stem is prostrate or creeping. Leaves are dark green, simple, opposite, margin is incised-toothed. Flowers with long peduncle, forming head or radiate type of capitulum; consists of ray florets and disk florets; ray floret few, pistillate, fertile, corolla is a slender tube, with bright yellow or pale yellow ligule, two-lipped, outer lip large, inner lip small; disk floret is bisexual and fertile, corolla united to form narrow funnel form throat, with short tube and five-fid limb; anthers long, narrow; style hairy above. Fruit is an achene, oblong, with many pappus and feathery bristles.
Pollen grain is simple, 3-colporate, shape is spheroidal. Aperture consists of a colpus (furrow) and a pore (circular opening); colpus is short, membrane with small granules; os (outline of pore) lalongate (transversally elongated). Exine covered with long , pointed spines.