Node culture

What are nodes ?

Plants build "sleeping" buds to make sure that it can survive if the apical bud dies (eaten by a pest, ...). As long as the apical bud is growing it produces a growth regulator (hormon) which suppresses the growth of the other buds on the stem. If the apical bud dies, the growth regulator is missing and the "sleeping" buds start to grow.

Where can you find sleeping buds ?

Nodes can be found e.g.:

• on the stalks of Phalaenopsis, Doritis and Phaius
• on bulbs of Dendrobium
• on bulbs of Cattleya ...

• Node culture in soil
• Preparing the nodes
• We have tried the following technique with Phaius tankervilleae and it works very good. One of our course participants successfully propagated his Phalaenopsis in peat. You can have a look at a photo of his young Phalaenopsis and his procedure when you click on the button below.
• Top of Form
• Bottom of Form
  • Suitable are nodes, which you cut with 3 cm below and above of the eye on the flower stalk. It is very important to us a very sharp knife because otherwise the tissue will be hurt to much. Next you have to remove the bract covering the node carefully.
  • Place the nodes in soil:
  • Place the prepared node in soil horizontal, the node should be on the highest point.
  • Moisten it well and close the box with plastic foil like the picture below shows.
  • Further care:
  • Place the box with the nodes on a bright warm place and prevent direct sun. Check them every 3-4 days if they are moisten enough.
  • fresh nodes
  • 4 weeks later
  • further 4 weeks later
  • further 2 weeks later

in vitro node culture

Preparing the nodes

The advantage of this technique is that the new plants are clones of their parents and look like they do. We have used this technique to propagate: Phalaenopsis, Doritis pulcherima, Phaius tankervilleae and Chiloschista lunifera.
Suitable are nodes, which you cut diagonal with 1 cm below and above of the eye on the flower stalk. It is very important to us a very sharp knife because otherwise the tissue will be hurt to much.

Phalaenopsis flower stalk with bract

Next you have to remove the bract covering the node carefully.

Phalaenopsis flower stalk (node) without bract

Which media should you use ?

To initiate the growth of the "sleeping eye" we have to use media which includes cytocinins (phytohormon). We use Sigma´s P6793 (Phytotechlab P793).

Preparing the flasking area:

You can use the same equipment we discribed under Seed sowing.

Flasking the nodes:

Dip the trimed nodes for a few seconds in 70% ethanol. After that put the nodes for 30 minutes in 0,5% hydrogen peroxide (H₂O₂). Next put them for 15 minutes in 3% H₂O₂. When the 15 minutes elapsed, place the sterilized nodes (in the test tube) on the grill which is lying in the steam (sterile area). Now, pick up a flask and open it in the steam. The cap should be placed on the ethanol soaked kitchen paper. Take your forceps and pass the flame of your candle to sterilize it. Transfer the forceps to the sterile area (steam) and catch one node which is swimming in the hydrogen peroxide solution and stick it with the end at the bottom of the node into the media.
Next, dip the forceps into the boilding water to remove all rests of media and transfer the forceps into the bottle with 70% ethanol. Close the flask (in the steam) and placed it somewhere on you desk for labeling. With the next flask you can process in the same way.

Hint: To make your sterilization solution more effective, add a drop of dish washing solution to your hydrogen peroxide.

Further care:

The place where you culture your nodes should be bright and warm (about 20 °C). Prevent direct sun because it will become to hot inside the flasks if they are standing in direct sun.

growing Chiloschista lunifera bud

Because of the size and the structure of the nodes the contamination rate is higher than using asymb. seed germination. So, it´s very important to check them in the first week every day if there are any contaminations. If you find some fungi or bacteria you can try to sterilize them once again.
Many nodes exudate phenolic compounds into media which make the media black. This phenolic exudations will kill your nodes if you don´t replate them to new media. Many nodes stop exudating phenolic compounds after 3 or 4 replatings.

phenolic exudations

As soon as the node has got 2 or 3 leaves you should replate it to media without hormones (e.g. Sigma P6668) to initiate root development.

What can I do if I want more than one plant ?

If you want to produce more than one clone you should cut the top 1/3 of the node. This will cause the node to put out up to a about dozen shoots instead of one.

Biology of orchid seed germination

Orchid seeds are very small (like dust) and do not contain any food reserves which feed the embryo in his first steps of life like other plants do (e.g. apple, beans). Because of this fact, orchids produce a high number of seeds (up to 1 millon in each capsule).

mature Phaius tankervilleae capsule

In nature the embryos swell a little bit but they will not form a seedling unless they are infected by a symbiotic fungus (mycorrhizal fungus) which supplies them with sugar and nutrients. As soon as the symbiosis is established each embryo becomes a little "ball" which is called protocorm. These protocorms turn green after a while and the first leaf and roots appear. From this stage the seedlings can live without the symbiotic fungus because the photosynthesis is active.

We have germinated seeds of Epidendrum radicans which build green protocorms after 2 weeks. Cyrtopodium punctatum protocorm took for the same stage more than 2 months.

Symbiotic germination in the pot of the parents

This is a very old technique which was used before in vitro culture was discovered. Here we use the symbiotic fungus which is growing on/in the roots of the adult orchid (which produce the capsule). The seeds are sown very close to the roots and are kept moist to start germination.
The number of seedlings is limited because many protocorms and seedlings get killed by pests and aggressive fungi.

Symbiotic germination (in vitro)

At this technique we have to isolate the symbiotic fungus from a root of the orchid where the capsule was produce. The fungus has to be established on a nutrient-poor media (e.g. oat meal agar). Next we have to sterilize the orchid seeds and saw them on the media which contains the isloated fungus. The seeds will germinate and produce seedlings if the isolated fungus is compatible with the seeds. If not, no germination will take place.
With this methode it is possible to rise much more plants from the same quantity of seeds as we can do with "Symbiotic germination in the pot of the parents".

Asymbiotic germination (in vitro)

To avoid the high effort, which is needed to isolate and test the fungus, we can "simply" ignore the fungus and add all necessary nutrients (which are provided by the fungus) to the media. The only thing we have to do is to cook the media and saw the seeds under sterile conditions on this media. For more details please read asymbiotic seed germination.

How can I get some seeds ?

Before you can start sowing seeds you have to solve the problem that seeds normally can not be bought in shops. So you have to pollinate your own plants. To pollinate an orchid the plant should be strong and healthy.
To start building a capsule you have to transfer the pollinia of one flower to the stigma of an other plant. If you have got only one plant or only one flower you can transfer the pollinia to it´s own stigma. Some orchids do not allow self pollination so we have to try if it acepts it´s own pollinia or not.

Here are some examples of flowers where you can see where the stigma and the pollinia are.

Diocentrum
Phalaenopsis
Burrageara
Oncidium
Paphiopedilum

Our pollination technique

We use wooden toothpicks to transfer pollinia. The best time to pollinate your orchid is when the flower has finished opening. Move the end of the toothpick into the flower an pull out the pollinia. Sometimes the pollinia does not stick on the tootpick. In this case you should use a forceps to pull them out. In the next step remove the anther cap and place the pollinia on the stigma, as close as possible to the entry of the stigma channel, of the other flower. Last but not least write down the pollination date and the name of the secound plant.

Basic rules to label the pollinated flowers

With some examples we want to show you the common way to label seed capsules and plants.

Harvesting capsules

The seeds inside the capsule have finished their development about 3/4 of the time the capsule needs from pollinia transfer till releasing the mature seeds. If you want to sow green capsules (in vitro) you can harvest them after this time. It´s very important that the green capsule has no holes or places where fungi could reach the seeds otherwise they are not free of contaminations (fungi, bacteria, ...).

For sowing dry seeds just wait till the capsule starts to open (dehisces) and then harvest it.

A very large list of seed-capsule ages is available at BARRY'S ORCHID PAGE.

You can order orchid seeds at ...

The Orchid Seedbank Project
Exotic Plants

Packing seeds

When you harvest a mature capsules you´ll have a high number of seeds available. Normally you do not need all of them. If you ever have tried to get some orchidseeds from other growers, you know how difficult it can be and how glad people are when they get some new seeds. In the internet you can find some groups where growers share their seeds.

Preparing the seeds

Before you start packing your dry seeds for shipping you should remove all contaminations (parts of the capsule, pollen tubes, ...). The best tool to do this is a forceps.

Packing the seeds

The paper in the pictures below is 10 cm wide and 10 cm high.

Germination on bark

Backgroundstory to this idea

A few months ago we read Anton Hefkas book "Cattleyen und Laelien" where he explains how he germinated about 100 years ago (1900) thousands of Cattleyas and Laelias at the botanical garden Schönbrunn. This was the procedure he used: "Put some crocks in a clay pot till they reach one third of the pots volume. Next, put sphagnum moss on the crocks till the pot is filled for two thirds. Last but not least fill fresh spruce saw dust pulp in the pot and disperse the seeds on the surface of the spruce pulp. Place the pot in a bright but not sunny area in your greenhouse and water them every day."
We tried to reproduce this methode but we were not able to germinate seeds this way. After this failed experiment we put some seeds of Pleione spec. and Epidendrum radicans on a piece of bark and they germinated very good. Within a few months we had very healthy seedlings. Because of the successful symbiotic germination we tried to reproduce it with different seeds but we were not able to repeat a successful germination. The seeds become protocorms but the neccessary fungus is not always present and so the protocorms die after a while.

The technique we used for our successful germination on a bark:

Before we can start to sow the seeds we have to collect some fresh barks from a local forest. After that we cut the bark into small pieces (about 5 x 5 cm) and put them for one hour in rain water. Next we dispersed the seeds on the moist barks and placed them in a modified plastic bottle as you can see on the picture below.

Further care:

Place the bottle (containing the barks) on a bright but not sunny area and water the barks as soon as the bark start to become dry. It is important to let the bark dry out a little bit before watering them again. We water them every morning.

Epidendrum radicans protocorms

Pleione seedlings

Seed sowing service

If you do not want to do all the flasking work we can offer you to send the seeds to us and we will sow them for you.

The seed donor will get 10 seedlings for free when the following conditions are fulfilled.

In all other cases seed sowing will be processed as followed.

For bigger orders please contact us for an individual offer.