This is an article I wrote for the Polish Kaktusy i Inna (Cacti and Others) way back in 2005.       und Deutsch

                    The Beginning
40 years ago, my grandmother had a few cacti. I have no idea which ones, but as far as I can recall, they looked like Arthrocereus, Cleistocactus, Epiphyllum, Schlumbergera, Selenicereus and Mammillaria.

They stood among other plants in the living room windows all summer, and all of them flowered. In the cold winters, the stove had no chance keeping the windows frost-free at night, and the cacti were placed in the basement, under a sheet of black plastic, and without  receiving any water for five month. I was five, and fascinated!

During the summers, we tried to pollinate them, with some succeed, and I got small cuttings as well. From time to time, I also got small cuttings from my parents friends, and my collection grew. It stood in a 60x40 centimetres window, facing south. I had two problems: In summer they grew too much, and in winter I had a hard time not to water too much. A habit I havenít been able to quit yet!

My parents and I started travelling, mainly the Middle East and the Mediterranean, and new cacti and succulents appeared. At itís peak, I had 63 different cacti and succulents in that little window.

Then cacti started to be popular in Denmark, and suddenly you could get new ones, not only at the flower shop, but also at the supermarket and even in the small stores in the gasoline stations. When you only have a 60x40 centimetres window, that isnít fun!

I got rid of the cacti, and started with a few strange succulents and epiphytes. In 1980, I got a small seedling of Beaucarnea recurvata; my first caudiciform. Then I discovered animals. Small amphibians, reptiles and insects. At the peek of this hobby, I had 170 different species. Made terrariums with the right plants, creating a natural habitat. Now, I brought back animals from my tours.

I left home, and suddenly, time was limited. No time for breading insects for feeding or maintaining the terrariums. If I canít make it perfect, I wonít do it. Keeping animals demands full attention.

I got rid of the animals, and started with plants again. Strange plants, mainly succulents, but all kind of weird growing would do. Most of the plants were collected on trips to Southern Europe and the Mediterranean. I brought back 115 different species from Tenerife. I had a large apartment with a lot of big windows, but unfortunately, I couldnít enjoy the view outside. I used 15 litters of water each day, and the condensation ran down the windowsill.

I moved, and had to get rid of some of the largest plants. My biggest problem was, just like with the cacti that my plants always get too big, and I do not like pruning them excessively. For some years, I worked a lot, and didnít have time for the plants. I bought a house, and the few remaining plants grew to enormous sizes. In 1990, I found a Dioscorea elephantipes, my second caudiciform. In 1998, I found a Adenium obesum in Thailand .

I moved again. Only two windows, each one meter. Cut back on the large plants, but kept the three caudiciforms. Two were slow growing, and the third was easy to prune back, when it was dormant.


Caudiciform Collection
I realised that these strange plants with swollen stems or roots were extremely rare in cultivation, and decided to get some more. With help from my girlfriend Rikke Jensen, I had 10 different in 2001. Some of them I bought on a trip to The Netherlands. They were Adenium obesum, Bowiea volubilis, Dioscorea elephantipes, Ipomoea batatas, Jatropha podagrica, two different types of Kedrostis africana, Beaucarnea recurvata, Turbina hulubii and Sinningia leucotricha.

I did not know anyone else who had plants like this. It was surely all the species I could find. Then I discovered the large collection in then Copenhagen Botanical Garden. The Chef-gardener; Jorgen Damgaard, had been collecting these plants for 30 years. He had worked in foreign botanical gardens, i.e. South Africa, and had build a great collection in Copenhagen. He was a great help for me in understanding both the care and the taxonomy, but I still hadnít a clear definition of, what I would be collecting.

In 2002, Rikke and I planned on going to Australia for half a year. I wanted to be able to show my plants there, and my good friend Jesper Pedersen build my first web-site. It has since gone from one page with ten photos to more than 1500 pages, more than 5000 plant photos and more than 2000 photos from other collections and habitats.

I brought back some plants from Australia, and learned the name "caudiciform". That gave me the first clear feeling of, what I actually was collecting. The collection exploded, and I chose to take an education as greenhouse gardener at Botanical Garden In Copenhagen. First half a year in South Africa in a nursery dealing with indigenous plants.

Before  I left, I donated my entire collection to Copenhagen Botanical Garden, and started a new, based on taxonomy in South Africa. Had that for a few years during my education, and cut it back to five huge caudiciforms, just before I finished. I started to collect only digitally, and even though I only have these five caudiciforms, I still have the interest!


My definition is: Caudiciforms are an unscientific grouping of plants, across divisions, orders and families. A common denominator is the perennial swollen caudex / bulb / stem / rhizome / pachycaul or similar.

I have members of the century-, yam-, dogbane-, milkweed-, madder-, morning glory-, cactus-, purslane-, kapok-tree-, cacao-, primrose-, primula-, cucumber-, passion-flower-, mulberry-, moonseed-, spurge-, grape- and other families. Everything from giant trees to small herbs.

For most of the species, the caudex is a water-reservoir for a dry period. Some of them have a hollow caudex, in which ants live. In return for this home, they protect it from other insects.

Some of the plants lose their branches and vines, when they dry out, leaving only the caudex and the bigger roots. This reduces evaporation. Others will (in nature) grow larger and larger, and only flower after many years.

Some of my plants are dioecious, which means that there are different male- and female plants. Others are monoecious; both male- and female flowers on the same plant. Unfortunately, that doesn't necessary mean they can self-pollinate. Luckily, it is possible to make cuttings of many of them. But, the cuttings don't necessarily form a caudex.

Some caudices lay deep down in the ground, protected from extreme weather conditions and animals.  Some of these don't stand to be exposed, which makes them less interesting to me. Others are partly exposed, and finally there are those which are fully exposed. This last can be a result of their habitat: Bare rocks with small cracks, leaving no room for a caudex.

Some of the caudiciforms are used as a crop around  the world, for instance yam. Others are highly poisonous, as a natural result of living in hostile environments, where every leaf is valuable for both animals and plants.


Acquiring the plants became easier. Jorgen Dangaard grow and sold plants in the little shop in the Botanical Garden, and a lady started a cacti-shop in Copenhagen. I got internet access, and found the FatPlant Newsgroup and other individuals.

Suddenly, I was buried in plants. I build in two glass windowsills in each window, had the pots in two and three rows. I had to restrict my self somehow. Others make their limitations by concentrating on one or few families. The Cucurbitaceae, Euphorbiaceae and Asclepiadaceae families are those with most members. I think the Asclepiadaceae show the greatest variation within one family. Some collectors restrict themselves to trees (pachycauls) but I like the variation, and decided to collect only one or two members of each family. That way, I would have some limitations.

I did a lot of research, and have found more than 100 families. There might be more, and some of these might be questioned. I do not claim to have the sole answer, it is up to the professional taxonomists and your personal liking.


Cacti with a caudex

There are several cacti, which more or less form a caudex. To name a few: Yavia cryptocarpa from Argentina is the most subterrestrial, and there is Ariocarpus kotschoubeyanus from the northern Mexico. Their extreme rough conditions force them to live almost underground. When the rains come, they swell, and peek up to reach for the sun. When drought starts, they simply dry down under the surface, and get covered with a protecting layer of dust. Their life is only maintained in the swollen root, the caudex.

In Mexico, we also find Peniocereus rose and Peniocereus viperinus, which grow in the heights. In winters, it can easily freeze, and the thin branches will die. Life is sustained in the caudex. The same goes for the Argentinean Pterocactus tuberosus. In Southern America , where the climate  is warmer, Pereskia diaz-romeroana forms swollen roots, simply to maintain water for the dryer summers.


Maintaining the collection
I think that most plants I have lost, died from over watering. I simply canít help it, watering all the time. Iím a compulsive waterer. Every day I promise my self: Tomorrow you shall not water more than the thirsty few. Every day.

In the beginning, it was humid. We are two persons and 130 plants in 20 square meters room. The windows face the central square, and noise prevents us for having the windows open for more than a short moment. I am sure I lost quite a few plants because of the 100% humidity. Everything else grew: the wall-paper, shoes and overcoats that hadnít been used for a week..

Then I bought a air-dryer. Picking three to six litres out of the air every day, keeping the humidity down on 50%. Good for the wall-paper, but now some of the other plants were dying. Those from the moist jungles, ant-plants and epiphytes canít stand the dryness.

I do not like to admit it, but it seems rather unlikely I can maintain all plants in the same small living room. But I try! Those who suffer in the dry air have their own little greenhouse. It is not optimal, but it works up to some degree. It seems like I can succeed with a humidity around 70%

Another factor, which I would like to be able to control better, is the light. My windows are facing west, and most of the plants are fare from getting enough sun. This gives long slim plants, not what Iím looking for. Artificial light might be useful, but not in my small living room.

The third factor, which seems to be a problem to me, is the pots. Because of my lack of limitation, the windows are packed. Where other collectors of plants re-pots to larger pots, I always re-pots to smaller ones. Most of the plants looks like bonsai, after a few years. This makes them vulnerable to drought and overwatering.

The fourth factor, which makes it a bit difficult, is insects and other pests. From time to time, I get green or black lice, but they are pretty easy to control. A few times I have got mealy bugs - or shield lice. It has only been the new plants, and a needle and some patience solved that.

Red spider mites is a completely different story: they seems to thrive in my dry air. I can control them, but they always seem to return on other plants. They seems to prefer the plants from cooler climates, which they can kill within a week. I give the plant a shower and use poison every week during the summer. I do not like to use poison, but I hate seeing small midges killing my plants!


How to maintain the plants
Every plant has its own needs, and I will not be able to get into that in one article. Generally, caudiciforms are desert plants. In the wild, they will get a month of rain, almost drowning, then drought for the rest of the year. They need a very well drained soil, lots of sun and a lot of fertilizer when in growth.

In the wild, they might only grow for a couple of months a year, but if  the water, the temperature and the sun remains, they might grow all year. Some will need to be dormant . Most of them donít stand frost or water during that period.  

For some people around the world, tap-water isnít good. It can be slightly salty. Others, like me, live in an areas with ďhardĒ water Ė water with lots of minerals. Not good for our plants either!

 I can get clean water from work: We have a diverse osmosis device, which takes 13 kg dry stuff out of 1000 L. Unfortunately, it costs around 5.000 US£, and only gives 60% of the water for use. Works fine for my plants, but recently, I have been using the water from my air-dryer. My room was too damp, always close to 100%. Paid around 200 US$ for it, and now I have 2-7 L. of clean water every day. I do not live in a area with air-conditioners, but Iím pretty sure you will get some clean water from that as well. I know it wonít be enough for large collections,  but Iím sure it will be of some benefit for the smaller, private collections.


Books on caudiciforms
There are only a few books on caudiciforms. Gordon Rowley has made some, and Philippe de Vosjoli another one. Generally, it is hard to find books. As I mentioned before, the caudiciforms come from so many families and countries, and books tend to deal with few families or areas. Books are extremely expensive in Denmark, and the libraries donít seem to be able to help much.


Caudiciforms on The Web
When I started surfing the web a few years ago, there were only a few sites with caudiciforms. More and more are coming, and I try to contribute as much as I can. First I made pages with my own plants. Then I tried to get hold on the families, making some taxonomy with only the caudiciform members. Then, I  tried to get hold on all the genera with caudiciform members., and recently, I have swept all sources for the remaining species.

My site might seem a bit confusing, or with a nice word overwhelming. There are more than 1000 pages with one plant each. Then there are pages with all the members of one family, pages with all the caudiciforms from one part of the world, pages with taxonomy, others with dormancy and water/sun needs. Photos from other collections and habitats. I have done a lot of travelling, and there are quite a few slide-shows, mainly with cacti, from Argentina and Mexico and slides with South Africa, Namibia and Bonaire .

It is generally made as a Google reference book, far too big to be read from one end to the other. There are more than 1500 pages total. Have a look at 

There are getting more and more sites on caudiciforms, but most information can be found at nursery pages, sometimes one or two plants in between many other plants. When I looked in 2002, there were eight! There are links on my site to those nurseries I find the most interesting.


Friends on The Web
As I wrote before, the internet access increased my contact with other collectors. For example the FatPlant Group, and also Maarten van Thiel, who has contacts everywhere, and knows all of plants and of web design. He has been the largest source of ideas when I made the design of my site. Further more, he can grow nearly anything from seed, an ability I surely donít have. Wojciech Zychowski, who can find anything on the internet, and is a great help getting plants out of the US . Many more have contributed, not only to my collection but also to my knowledge. Without the web and the people attached to it, I would still have only ten plants, which I desperately tried to keep alive.


I find caudiciforms fascinating in more then one way. The are weird, kind of ugly and at the same time beautiful. Most of them come from a very hostile environment, to which they have adopted. Even though they are from such different families, living in different parts of the world, they have solved the problem with the dry period of the year in the same way. They are generally quite easy to cut back, and will actually get more beautiful doing so. I my small house, with lack of light, but warm in winter, it is nice to be able to cut them back, and place them in a dark corner. Finally, a quest. Many of these plants are extremely hard to find. When you finally recover it, it will follow you (and you follow it) for many years.


This is how the site started. My good friend Jesper Pedersen transferred the data from my Psion Revo to a single page, and added the photos. It was in 2001, and in Danish.
My main reason for making all this, is simple: I do not have any memory at all. I do have to write all down, and why not share this knowledge? In September 2004 the number of pages reach 500, September 2006 it passed 1000, April 2009 it passed 1500 and new ones are still coming on - although I have a hard time finding new ones!.

              Bihrmanns Planter      Ver. 1.0  Hvis du har rettelser eller kommentarer.     

Adenium obesum Apocynaceae Afrika Mix Max Max 0,5m5m Pink* Se/Cut Bangkok '98
Bowiea volubilis Liliaceae S Afrika Peat Max Max 0,1m?m Whi/Gre* Se/Root KÝbenhavn '00
Dioscorea elephantipes M+F? Dioscoreaceae S Afrika Peat Max Max 1,0m5m Yellow Seed Roskilde '90
Ipomoea batatas Convolvulaceae S Afrika Mix Max Med   Pink*   KÝbenhavn '00
Jatropha podagrica Euphorbiaceae C Amerika Peat Med Med 0,2m1,5m Red* Seed Roskilde '90
Kedrostis africana (round) Cucurbitaceae Afrika Mix Max Med   Yellow Se/Cut Amsterdam '00
Kedrostis africana (serrate) Cucurbitaceae Afrika Mix Max Med   Yellow* Se/Cut Amsterdam '00
Nolina recurvata (Beaucarnea) Agavaceae Sō Mexico No Max Max 1,5m8,0m   Seed Roskilde '80
Turbina hulubii (Ipomoea) Convolvulaceae S Afrika Grit Max Max   Pink*   KÝbenhavn '00
Zinningia leucotricha Gesneriaceae Brazilien Mix Med Max 0,3m?m Orange* Se/Cut KÝbenhavn '00