Trichocereus Blog: Trichocereus Macrogonus

Trichocereus Macrogonus – Echinopsis Macrogona

cereus macrogonus SD. Cact. Hort. Dyck.Cult.

Current name: Echinopsis Macrogona.

The fact that the plant now known as Trichocereus Macrogonus was described BEFORE what we know as Trichocereus Peruvianus might actually lead to the abolition of the name Trichocereus Peruvianus, if the people in charge of taxonomy declare them synonymous because the older name has priority. However, many people cling on the name Trichocereus Peruvianus because it is very traditional. So it´s unclear which name will stick. Most up-to-date books include both species.

Synonyms: Cereus Macrogona, Echinopsis Macrogona, Trichocereus Macrogona, Trichocereus Glaucus, Echinopsis Glaucus, Echinopsis Glauca, Trichocereus Glauca, some types of Trichocereus Peruvianus

Trichocereus macrogonus in the Huntington Botanical Garden by Richard Hipp

Origin: Unkown. Possibly Bolivia but the species could never be found in Bolivia again. Originally, it was assumed that the plant came from Brasil and Borg wrote that the plant came from bolivia or argentinia but that could not be verified. Rauh found a trichocereus in 1954 (collection number K68-1954) that may have been the wild trichocereus macrogonus. That plant was found around the Mantaro Area in the middle of Peru.

This is the plant in question, and judging by its looks, it could actually be the originally described Trichocereus Macrogonus. Back then, the plant was described as Cereus macrogonus (Salm-Dyk) and I know a very similar plant that was distributed by Karel Knize.

And this pic is from Backeberg´s description and shows a plant that is very common in European collections!

Echinopsis Macrogona or Trichocereus Macrogonus is a columnar cactus that is very close to Trichocereus Peruvianus or Echinopsis Peruviana. Echinopsis Macrogona is most likely synonymous with a certain, long-spined type of Peruvianus. The typical epidermis of Trichocereus Macrogonus has a frosty, blue color. Trichocereus Macrogonus grows columnar and can get up to 3 meters tall and 3-5 centimeters in diameter. Some very large species can even reach a higher diameter. It has 6-9 radial thorns and 1-3 middle thorns that are up to 10 centimeters long.

Spines: The spines are dark brown, black or gray in color. New spine growth can also be yellow. The problem is that there are countless types that are called “Trichocereus Macrogonus”. Some definitely belong in the Trichocereus Cuzcoensis complex while some others are a very frosty type of Trichocereus Peruvianus from Matucana.

Areoles: About 2 centimeters apart from each other and 5-10 mm in diameter. Brown-felted.

Flowers: White, near the top and up to 18 centimeters long. Trichocereus Macrogonus is a night flowering species.

Fruit: Round fruit, shiny segmented fruit, black or dark brown in color.

Trichocereus Macrogonus is self sterile what means that you need two different species´to get seed.

Culture: The culture of Trichocereus Macrogonus is very easy. Basically, it has exactly the same requirements as Trichocereus Pachanoi (San Pedro Cactus) or Trichocereus Peruvianus (Peruvian Torch). It is a very hardy plant that forgives a lot and as long as you treat it like a cactus instead of a swamp plant, it will pay you back with healthy growth every year. The cactus only needs water during the hot, growing seasons. That means that in summer, you can water it every week or even days as long you allow the soil to dry up between waterings. You can improve the drainage of your soil by adding purely mineral substrates like pumice, clay substrates like Seramis or simply sand. However, you should add a very small part commercial cactus soil because you want the substrate to be able to store nutrients and purely mineral substrates like sand tend to wash out nutrients very easily. Trichocereus Macrogonus likes a place with half-shade that gets a fair amount of sunlight every day. However, you should make sure not to burn the hell out of it. Especially when the plants are coming from your winter storage and are not adapted to the strong sunlight yet.

Winter & Frost: Trichocereus Macrogonus is a very hardy cactus that can take short night frosts down to -9° Celsius as long as the general health of the plant is ok. However, it requires a minimum average temperature of 10° celsius. That means it can take short frosts down to 15.8° Fahrenheit as maximum frost temperature. The average minimum temperature in Fahrenheit is 50° Fahrenheit.

Winter storage & Winter Protection: Trichocereus Macrogonus likes a bright spot with lots of fresh air during the wintertime. If you have the luck to live in a country with very little frost, like Australia or the hotter parts of the USA, you wont have the problem of winter storage because you can grow your plants outside but most people in other parts of the world are not able do that. So yeah, it´s best to store cacti in a very bright room with fresh air supply to prevent mold. The minimum temperature should be around 9° celsius/50° Fahrenheit. For this type of winter storage, the plants need to be kept dry, without any waterings in between October and April. If you have a greenhouse, you can start taking out the plants by May, but be careful about late night frosts because some south american species that take frost very well. For Trichocereus Macrogonus, this should not be a problem though.

Germination of Trichocereus Macrogonus: The seeds of Trichocereus Macrogonus are like most other Echinopsis & Trichocereus seeds. They need light to germinate and should be sprinkled on top of the soil. They require a minimum germination temperature between 25° and 30° celsius and seedlings need to be watched carefully to prevent heat damage, because though temps up to 30° celsius increase germination rates, everything above can kill the young seedlings in an instant. Watch out for mold or fungus gnats. However, Trichocereus Macrogonus seedlings are actually tough.

Where to get seed: There are many seed suppliers that sell seed of Trichocereus Macrogonus. However, be cautious because there one or two south american wholesalers that sell over aged seed. Please not that there are some extraordinarily good Seed distributors from South America so there is no general rule of thumb. That´s how life is and I would recommend you to test the seed you are offered before you buy a substantial amount of it. I have seen people tank hundreds of dollars for seed that produced one or two seedlings.

Seed Viability, Trichocereus Macrogonus: The seed is viable for many years. This is something that most Trichocereus have in common and the seed is probably viable for at least 5-10 years, though you get the best results within the first year.

Varieties offered as Trichocereus Macrogonus: KK923 Trichocereus Macrogonus (Cieneguillas, Bolivia), KK1422 (Villa Abecia, Bolivia), KK2151 (Ayacucho, Peru), KK2175 Apurimac Pachachaca (Bolivia), KK2176 Ayacucho, Tr. Macrogonus H1306 from the Huntington Botanical Garden, Trichocereus cv. Neon Palm, Trichocereus sp. Luther Burbank, Trichocereus SS01, Trichocereus cv. Oklahoma, and many more. List will be updated. If you know some more, let me know. But the fact that you could as well list all of those as Trichocereus Peruvianus makes this kinda pointless. Both types are synonymous and I just added this page because I dont want to leave it out.

This here is what grows out of Köhres Trichocereus Macrogonus Seed: