Division, perennials

Perennial vegetables such as globe artichokes and rhubarb crop much more quickly if grown from divisions or "offsets" taken from a mature plant (see also Herbaceous Plants, p.J93) rather than seed. Asparagus should not be harvested until plants are in their third year, so one-year-old plants, known as crowns, are usually planted (see above, far right). Jerusalem artichokes are grown from tubers, like potatoes, and seakale from sections of fleshy root known as "thongs."... 

Dividing giobe artichokes These large perennials will be reinvigorated by division every three or four years. 

By contrast, nodule meristem development in indeterminate nodules, such as those of Medicago and Pisum, is initiated in the inner cortex adjacent to the endodermis (Dudley et al., 1987). The meristem of indeterminate nodules functions for months or even years in the case of some woody perennials (Dart, 1977). The meristem differentiates into a dome shape due to cell division in a single plane. Cell division followed by cell enlargement results in an elongate, cylindrical-shaped nodule (Fig. 5). As nodules grow, other meristematic areas often differentiate, resulting in the formation of a branched, corraloid-type nodule. 

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