Asexual Reproductionvegetative Reproduction

Man has capitalized on the natural tendency of plants to reproduce asexually in order to propagate them vegetatively. We outline here only the general techniques for the commonly used vegetative reproduction procedures to avoid needless repetition. Specific requirements, such as ideal temperatures, have been described in the chapter devoted to each genus.

Asexual or vegetative propagation in carnivorous plants can be organized according to the organ of the plant utilized.

Stem

Rhizome break-up: Large rhizomes are cut into sections about Vz in. (1.3 cm) long. If roots are present, care should be taken to not damage them. Dust the rhizome ends with a fungicide, then place the rhizome sections in damp growing medium in a horizontal position so that the top of each section is about k in. (0.6 cm.) below the soil surface. Keep them damp in a high humidity and well-lighted environment, but not in direct sunlight, until new growth develops.

We have found that living sphagnum moss gives the best results and is a deterrent to decay. The rhizome sections can be placed in the growing medium in a plastic bag which when sealed results in a self-contained unit that usually will not require any additional care until the plants are ready to be transplanted. Genera that can be propagated by rhizome break-up are Sarracenia and Cephalotus.

Rhizome proliferation: Remove all the leaves from a rhizome. Cut off about A in. (2 cm) from the growing tip of the rhizome. Place the remaining portion of the rhizome horizontally in the damp medium so that about Vz of it is above the medium, after dusting the cut surface with fungicide. (Photo 9-1) Dust the cut end of the removed terminal piece with a fungicide and plant it, cut end in the medium, up to about Vz of its length. In several weeks the planted terminal tip cutting will develop into a plant and several buds should start to develop into plants on the half buried rhizome.

After the new plantlets have developed roots they can be cut apart into separate plants. If the rhizome is small, rather than trying to take a tip cutting, simply cut off the growing tip with a knife or your fingernail. Once the undeveloped bud (growing tip) is removed you should have reached the rhizome which is whitish in color and somewhat woody. The debudded rhizome should be planted as outlined above. The rhizomes of species such as Sarracenia purpurea and S. psittacina tend to grow in a vertical direction and are usually very short. Since the rhizomes are so short, it is difficult to take a tip cutting. In this case remove the terminal bud as outlined previously for small rhizomes. Then plant the rhizome vertically so that about % of it is above the soil level. Sarracenia plants can be propagated by rhizome proliferation.

Stem Cuttings

Since the procedure for taking stem cuttings is different for each of the 3 groups of plants that reproduce easily by stem cuttings, each group will be dealt with separately.

Nepenthes

Cuttings consisting of 1-4 nodes, regions of the stem where leaves are attached, are removed from the plant. We have found that cuttings taken any time of the year will root successfully. About V2-/3 of each leaf on the cutting is removed and discarded. (Fig. 3-13) The lower end of the cutting is dusted with a hormone such as Rootone, which usually contains a fungicide, to promote rooting. All cut surfaces of a cutting should be treated with a fungicide or powered sulfur to inhibit or delay decay.

The cutting is inserted in a pot containing the medium. Living or dead sphagnum moss seems to give the best and the most consistent results. By placing the cutting in a pot it will not have to be transplanted for at least a year or two, at which time the cutting should have a well developed root system. The cutting is inserted into the medium so that 1-2 nodes are above the growing medium. If a 1-node cutting, the node should be just slightly below the soil level with the leaves extending above the soil.

The pot containing the cutting is placed in a plastic bag which is sealed to maintain high humidity around the cutting. The entire set-up is kept in a well-lighted area but out of direct sunlight. Optimum temperatures are between 70-85° F (21-29° C).

The cuttings should be kept moist at all times, but not waterlogged. It is better to have them a bit on the dry side rather than too wet, as excessive moisture promotes decay. Cuttings will root in a few months, but usually take 8-12 months to become well established plants with vigorous growth of new leaves and traps.

The remaining portion of the plant from which the cuttings were taken, often called the mother plant, will develop new growth from the undeveloped buds in the remaining leaf axils. The buds are normally prevented from growing by hormones produced in the terminal end of the stem which, when removed, eliminates the source of the hormone. As each lateral bud grows it will provide you with more stem tissue for more cuttings. Detailed information on propagating Nepenthes is found in the chapter on this genus.

Drosera

To propagate Sundews from stem cuttings, remove the top 2-3 in. (5-8 cm.) of the plant, including the leaves. Dust the cut surfaces with fungicide. Insert the cutting in a pot of sphagnum moss (living or dead) or sphagnum peat moss so that about 3/4 of it is below soil level. Place the cutting in bright but not direct light and high humidity. Roots should form in 3-8 weeks.

We have found that this works with all the Drosera spp. having elongated stems.

Some Drosera spp. can be propagated asexually by decapitation. This means the plant is cut off at or just below soil level. The base of the cut off top is then placed firmly on the planting medium surface if it is a rosette type. (Fig. 9-3) If an elongated stem type about V2 of the stem should be inserted into the medium. The cutting should be handled just like other Drosera cuttings. In a few weeks they will root and continue to grow,

In addition, the roots which are left in the soil will now produce another plant. This technique can be repeated when another plant has grown from the roots. We have on« batch of roots which had been decapitated continuously for 12 years. Species which we have propagated this way are Drosera binata var. binata, D. binata var. dichotomn, I) capensis, D. hamiltonii, D. adelae, and D. schizandra.

Aldrovanda and Aquatic Utricularia

Stem cuttings of Aldrovanda and aquatic Utricularia are taken by cutting the plant into sections about 3 in. (8 cm) long. The sections are then returned to the water. Each plant section will develop into a new plant in a few weeks.

Leaves

Leaf cuttings are prepared from leaves which are removed from plants and then arc layed flat on or inserted in the medium and in some cases floated on water. After removing the leaves from the plants, treat them with a fungicide, particularly at the point where they were attached to the mother plant. Best results are usually obtained with mature, older leaves which contain more stored food. The medium must be kepi damp and the humidity high. Placing the leaves in sealed plastic bags simplifies care.

Buds appear on the leaves in 2-8 weeks depending on the species and environmental conditions. Leaves of some species of Pinguicula and Drosera, Sarracenia, Cephalotus, and Darlingtonia can be used.

Roots

Roots of species such as Drosera binata var. binata, D. binata var. dichotoma, D. adelae, D. hamiltonii, D. capensis, D. schizandra, D. spathulata, and Byblis gigantea can be induced to produce new plants. The thicker roots give better results. Fifty percent or less of the roots can be removed. Cut the roots into 2 in. (5 cm) lengths or they can be left whole. The pieces are placed on damp medium preferably sphagnum moss, and placed in a humid, bright area, but not in direct sunlight. If they are placed in a sealed plastic bag, maintenance will be minimal. New plants should be visible in 2-10 weeks.

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