Summary

John Lindley Edwards's Botanical Register, Appendix to the First Twenty-three Volumes…

Drummond says, that "the bulb is renewed every year in the centre of several layers of bark-like substance, one of which layers is added every year by the decay of the old bulb. If the young bulb is dissected at the time when the plant is in flower, the layer of fibrous substance, which afterwards becomes the covering, is easily perceptible; it terminates in a point, which the following season becomes a root, and another root is produced from the bottom of next year's flower-stalk. In planting these roots the fibrous substance should not be removed, or the plant will not thrive.
Source: Wikisource

John Lindley Edwards's Botanical Register, Appendix to the First Twenty-three Volumes…

It appears that many of the species, such as Thelymitra, Macdonaldia, Pterostylis, Diuris, Prasophyllum, &c. have roots like those of the English Orchis morio, (fig. 1) , and they will require the same kind of management.*
The mode of growth of others is quite different. The greater part of them have the roots extended to a considerable distance, that is, to the depth of several inches, underground, terminated by a bulb, and thickly clothed with numerous dry loose skins.
Source: Wikisource

John Lindley Edwards's Botanical Register, Appendix to the First Twenty-three Volumes…

All the time they appear aboveground the weather is seldom warmer than in England in the month of May." Such plants as Caladenia (fig. 3 & 3*) deviate a little from this manner of growth, their roots forming knots, analogous to those on the roots of Arrhenatherum avenaceum, and ought, Mr. Drummond thinks, to be considered rather as reservoirs of nourishment, to enable the plant to flower and perfect seeds, than as true bulbs or buds.
"Young plants may be produced by dividing the roots; but they spring from the joints between the swellings of the root.
Source: Wikisource

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