Family: Lamiaceae
Common name: False ironwort, Knobweed
False ironwort is an erect, annual shrub that grows in the wild, and hence this plant is considered invasive in many parts of the world. These plants can be seen in most tropical countries, thriving in disturbed areas like roadsides and grasslands.
Plant characteristics
False ironwort plant grow to a height of 1-2 meters with an erect well-branched stem that is woody towards the base of the plant, and tender green towards the tip.
The stem is square in cross-section, a common characteristic of the Lamiaceae or mint family. Stem has a reddish tinge at the nodes, and is covered with small white hairs giving it a rough texture.
Leaves are ovate or lance-shaped with serrated or toothed margins, about 6-10 cm long. Both leaves and stems have a minty aroma when they are crushed, making the plant a good pest repellent.
Flowers are very beautiful and unique – small, white, tubular flowers arranged in dense clusters on the outer rim a dome-shaped flowerhead.
Each flower is 4-6 mm in diameter and have a pleasant fragrance that attracts small insects, bees, and butterflies to them. False ironwort plants usually flower in spring and summer producing numerous, dense, dome-shaped flowerheads filled with flowers.
Once pollinated, the False Ironwort flowers turn dark brown producing small, dry, hard seeds that are 1-2 mm in diameter. These seeds are dispersed through wind, water, or small animals.
They are quite hardy and can remain on the ground for many years, before they germinate and produce new plants.
Growing tips
False ironwort plants need good sunlight and well drained soil, though they are tolerant of poor soil conditions and some waterlogging. They are usually not grown in gardens since the plants do not have attractive foliage or large colorful flowers.
Since these plants grow in the wild, they are very sturdy and do not need watering, fertilization, pruning or pest control. They grow rapidly, producing flowers and seeds in season, propagating through seeds or through small suckers that grow at the base of the parent plants.
Due to the invasive nature of these plants, it is advisable to remove them from agricultural land or from gardens before they flower and fruit.
Uses of False ironwort
Parts of the plant have been used in traditional herbal medicine to treat cuts, wounds, infections, and digestive disorders. The aromatic leaves and stem make them a good addition to herb gardens.
They can be grown in gardens as natural pest repellents, though you should be careful that they don’t become rampant, effectively choking other plants. False ironworts can be grown as hedge plants because of their bushy growth habit.
Propagation
Propagation is through seeds, stem cuttings, and through suckers.
Each plant produces hundreds of seeds that can fall on the ground and germinate increasing the population of these plants. Stem cuttings taken from mature, healthy plants are capable of growing roots very quickly.
Photographed at: Koonammavu, Kerala
