Natural Methods of Vegetative Reproduction

Natural vegetative reproduction takes place through adventitious buds that develop directly on a parent plant's root, stem or leaf; once these buds detach they grow into independent, genetically identical plants, so no genetic variation is introduced. In reproduction by roots, some plants such as Murraya, Dalbergia and Millingtonia develop vegetative or adventitious buds directly on their roots; a few, like Ipomoea batatas (sweet potato) and Dahlia, additionally store food in tuberous adventitious roots, and once such a root becomes detached from its parent it grows into an independent plant under suitable conditions. In reproduction by stem, several underground and sub-aerial stem modifications serve as natural propagules: the rhizome of Zingiber officinale (ginger), Musa (banana) and Curcuma longa (turmeric); the corm of Colocasia and Amorphophallus; the tuber of Solanum tuberosum (potato), whose surface 'eyes' are actually axillary buds; the bulb of Allium cepa (onion, a tunicated bulb with concentric fleshy scale leaves) and Lilium (a naked bulb with loose scale leaves); the runner of Centella asiatica; the stolon of Fragaria and Mentha; the offset of Pistia and Eichhornia (water hyacinth); the sucker of Chrysanthemum; and the axillary bulbil of Dioscorea and Agave. In every case, axillary buds borne at the nodes of the rhizome or in the 'eyes' of the tuber are what actually give rise to the new plants. In reproduction by leaf, some plants form adventitious buds directly on their leaf margins; well-known examples are Bryophyllum, Scilla and Begonia. In Bryophyllum the fleshy, notched leaf margin bears epiphyllous buds at each notch that develop their own root system and become independent once the parent leaf decays; in the bulbous plant Scilla, similar epiphyllous buds form at the tips of the long, narrow foliage leaves and root into new plants wherever the leaf tip touches the soil. Natural vegetative reproduction has a single major advantage over sexual reproduction - only one parent is needed, the offspring are genetically identical, and in weeds such as Spinifex it allows extremely rapid spread - but this same genetic uniformity is also its chief disadvantage, since no new g …