Tuberous roots

Some herbaceous perennial plants die back to a crown of buds each dormant season, and their roots are modified to store food. These specialized swollen roots are described as tuberous roots. They can be distinguished from modified stems by their structure and from root cuttings by their inability to produce adventitious buds on isolated roots and so grow a new plant.

There are two basic kinds of tuberous roots: those that develop annually, such as on dahlias, and those that are perennial and simply increase in size, such as on begonias.

Annual tuberous roots develop from lateral roots at the crown of the plant. During the growing season, certain of these develop as food stores, swelling up and producing a cluster of such roots. Each year the new shoot system develops at the expense of the food store in the tuberous roots, which eventually die and disintegrate.

Perennial tuberous roots are much simpler in their development. Usually the emerging radicle of the seedling begins to modify as a food storage organ, and this increases in size as and when food is available.

The division of tuberous roots is not a widely used technique as many plants with tuberous roots can be propagated more satisfactorily by stem, leaf and leaf-bud cuttings. Success depends on how well the roots are stored. Lift the plant at the end of the growing season. Clean the crowns and dust with a fungicide. Wrap each plant in thick newspaper and place in a frost-free environment, below 5°C/42°F.

Just before the growing season, divide the tuberous roots into portions, each with at least one crown bud, from which the new stem will develop. Protect all cut surfaces from rotting by dusting with a powder fungicide such as Thiram or Captan. Then place the divisions in a warm (21°C/70°F), dry, airy area for a couple of days so that the cut surfaces seal themselves quickly by developing a corky layer of tissue, to give added protection. Pot up the divisions in John Innes No. 1 compost if they are to be transplanted within a month or so; otherwise plant them in John Innes No. 2 compost. Label them; do not water. Place in a frost-free area. Set in the light once a shoot appears.

1 Lift a plant at the end of the growing season. Clean the crowns thoroughly.

2 Dust the entire crowns with a fungicidal powder. Lift on to some newspaper.

3 Wrap up the plant. Store in a frost-free place until the buds begin to swell.

PERENNIAL TUBEROUS ROOTS

PERENNIAL TUBEROUS ROOTS

Begonia Plant With Tuberous Roots
Plants such as begonias have only one tuberous root, which is perennial and extends sideways each year.

ANNUAL TUBEROUS ROOTS

ANNUAL TUBEROUS ROOTS

Some tuberous rooted plants such as dahlias produce annual storage roots that die and disintegrate after one season.

Fungicide Bulb Dust

4 Divide the swollen roots into portions, each with at least one crown bud.

5 Dust all cut surfaces with fungicide. Leave in a warm, dry, airy place.

6 Pot up the cuttings once the cut surfaces have formed a corky layer.

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Responses

  • alberto
    How do tuberous roots store their food?
    8 years ago
  • Petros
    How is food stored in tuberous root?
    7 years ago

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