Propagation vegetative

Plant part The fresh or dried herb. The plant is native to the temperate zones of the Northern Hemisphere and cultivated in Russia, France, Germany and southern Europe. Among the cultivated forms a distinction is made between French tarragon , which must be propagated vegetatively, and the less aromatic Russian tarragon . 

Kava is an attractive shrub (Figure 1.1) that is propagated vegetatively, as are most of the traditional Pacific crops. The active principles are a group of psychoactive chemicals called kavalactones or kavapyrones (Chapter 5), which are concentrated mostly in the rhizome and roots, and in other parts of the plants to a lesser extent. The desired physiological effects are obtained by ingesting the active compounds present in cold-water infusions of ground, macerated, pounded, or sometimes chewed kava stumps and roots. 

Since the tree onion is propagated vegetatively, the material is genetically uniform. The root-tip chromosomes of the tree onion are shown in Fig. IB. Their number is the same as that of A, cepa, viz., 16, and they are of about the same size as the cepa chromosomes. However, the proliferum chromosomes are easier to identify than those of A. cepa. In proliferum the chromosomes do not form identical pairs. Thus, the root-tip cells of A. proliferum have only one satellite chromosome, which has a larger satellite and a shorter short arm than the pair of satellite chromosomes in A. cepa. (This satellite chromosome is, in fact, very similar to those of A. fistulosum, which supports the suggestion that the tree onion is more closely related to A. fistulosum than to A. cepa.)... 

Plant propagation vegetatively or by seeds, plantlet cultivation ... 

Many plants form viable interspecific crosses. Often these are sterile, which results in seedless fruits. Seedless varieties must either be hybrids of seed-producing parents or propagated vegetatively. Sometimes breeders use colchicine to induce polyploidy, resulting in a sexually reproducing interspecific hybrid with a double chromosome complement. 

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