Erigeron sumatrensis: Fleabane

Family: Asteraceae
Common name: Fleabane, Tall fleabane, White horseweed, Sumantran fleabane, Guernsey fleabane

Fleabane is a pesky, persistent weed, seen in open areas, undisturbed land, roadsides, hillsides, and almost anywhere. Though it is native to North America, the plant is now seen all over the world. They can grow to a height of 1-2 meters, including the tall stalks that carry bunches of flowers.

Leaves are lance-shaped, borne on thick green or reddish-green stems that are covered with short, white hairs. Fleabane plants branch well, producing clusters of leaves that are 5-8 cms long, with lightly serrated margins. These plants can bloom during almost any time of the year, especially in warm, tropical weather.

Flowers are borne in large bunches that have multiple flowerheads, each of them bearing hundreds of small flowers that are 5-8 mm long. Flowers are so thickly arranged that different flowers are in different stages of maturity in a single flowerhead, some underdeveloped buds, some barely open, some fully open like small pom-poms, some spent and brown.

Seeds are numerous, each flowerhead producing thousands of seeds, helping the plant invade new territories very quickly. Dandelion-like seeds are dispersed by wind or water, and spread over large distances. Fleabane seeds are about 1 mm long, excluding the pappus, or tuft of white hairs on top, which helps the seed fly.

These plants are considered as invasive weeds in most parts of the world, because of their fast growth and quick spreading nature. In agricultural land, Fleabane plants can choke small seedlings with their dense leaves, causing significant damage to crops.

Removal of fleabane plants is best done before they flower and produce seeds, either by tilling or hand-plucking. This would have to be done frequently since seeds from previous batches of plants might lie dormant in soil, till the conditions are suitable for germination.

In addition, new plants might come up through wind, water and animal dispersal. Fleabanes are extremely drought-tolerant, and can also withstand pollution, poor soil and extreme weather conditions.

Propagation is through seeds and stem cuttings.