Pollination system and hybridisation of Tabernanthe iboga: successful crossing of two forms with different fruit morphology.
Tabernanthe iboga (family Apocynaceae) is native to Western Africa; Angola, Cabinda, Cameroon, Central African Republic,…
Psychotria viridis (Chacruna) is an amazing South American rainforest shrub traditionally used in the Ayahuasca brew. I have been growing this species for almost 20 years and have propagated thousands of plants, both by seeds and also vegetative means (leaf cuttings, tip cuttings). I am constantly learning about its requirements for growth and find that it is a highly adaptable species tolerant of many conditions. I hope to provide a good (I do say ultimate so I’ll try hard) guide for those wishing to grow their own.
Psychotria viridis is a member of the Rubiaceae family, which includes medicinal and economically important plants like Coffee (Coffea spp.), Cat’s Claw (Uncaria spp.), Quinine (Cinchona spp.) and Kratom (Mitragyna spp.). The Psychotria genus contains 1582 species (at last count) and is one of the biggest flowering plant genera. P. viridis was firstly described in 1779 by Ruiz and Pavón. The specific name viridis comes from the latin word for green (I guess it has a beautiful and vibrant green colour). It is represented by shrubs and grows naturally in flat and humid forest areas from the northern region of Central America to Central South America. It is most commonly found in the Amazon region of Peru and northern Bolivia (Psychotria viridis: Chemical constituents from leaves and biological properties. Dé. Soares. 2016)
‘Amazonian soil is naturally acidic, as most basic compounds have been washed away by leaching. The average pH of the Amazon rainforest is in the range of 4.17 – 4.94.’ Negreiros, G. H. de; Nepstad, D. C. Mapping deeply rooting forests of Brazilian Amazonia with GIS.1994.
Psychotria viridis likes a well drained soil or potting medium, doing well in most loam soils. I initially dismissed the importance of soil pH in growing Psychotria viridis but have recently found that they do struggle and show signs of burning/deficiency in soils with pH around 7. Using coco peat as a base for my potting mix, I now incorporate some sulphur powder to lower the pH (it turns into sulphuric acid over time), as coco peat is a relatively neutral medium (around pH6-6.8). Like the Amazonian soils, aim around pH5-5.5 which will still give you good availability of all nutrients.
My soil blend for Psychotria viridis and hybrids:
Psychotria viridis loves regular watering. Once that soil dries out, they are fast to tell you that they need a drink, by wilting quite quickly. It denies their hardiness however, as they respond very quickly to a good drink, even as drinks become farer apart, like in Australia, where rainfall events can be months apart, unlike in the Amazon. So make sure they receive a regular weekly drink at the least and that the water drains away and doesn’t pool.
Chacruna will do best in a part shade position, as well as being generally taller and a healthier greener colour. Plants placed in a full sun position will have more yellowish/lighter green coloured leaves as well as having smaller leaves. I think the ideal shade percentage is 30-50% if you are growing under cover. They are tolerant and deep shade can be preferable to a full sun position in Australia.
Fertilise every 2-3 months or more regularly if needed and they are growing well. Most products work just fine. I have been using a homemade biochar fertiliser recently which has been greening my plants up remarkably. Foliar feeding works very well and you can incorporate seaweed as well as fertilisers. Dynamic lifter type products can be great to help green Psychotria up quickly, plus it stimulates biological activity in the soil.
I have also found what I believe is a reaction of Psychotria viridis to biuret in fertilisers, and have accordingly switched to fertilisers suited to Citrus plants, as they also have an intolerance to biuret. See below.
In the past, urea manufacturing processes sometimes resulted in fertilizers with elevated biuret concentrations. In high concentrations, biuret interferes with internal N metabolism and hinders protein formation in plants. Biuret is degraded by many soil microorganisms, but the rate is relatively slow. Modern urea manufacturing typically results in biuret concentrations less than 1.0 to 1.3%, which does not pose problems for most uses. There are some plant species that appear to be especially sensitive to biuret, so “low-biuret” urea should be used for foliar application in these situations. (http://managingnutrients.blogspot.com/2013/01/biuret-in-urea-fertilizers.html)
Pests of Psychotria viridis in cultivation include mealy bugs, aphids and scale (farmed by ants), spider mites, broad mites, tip grubs, stem borers and various caterpillars. All these (except for ants which I find the hardest to get rid of and which are generally the main problem) can be easily controlled with relatively harmless compounds like wettable sulphur, natrasoap or pyrethrum. One of the best tools I find is oil based products. Chacruna is highly tolerant of oil based sprays like White Oil or preferably a natural eco oil. 5-10ml per L is tolerated well several times a year. They come up with a brilliant sheen, typically like when you spray indoor foliage plants, they seem to love it.
Propagation of Psychotria viridis can be achieved several ways. Seeds are best harvested when fully ripe, cleaned and sown fresh; germination in this case will take 2-5 months. Older seed can take 4-9 months. The seeds have an immature embryo which needs time to mature. I have discovered that soaking freshly harvested seeds of Psychotria viridis and hybrids in gibberelic acid (GA3) decrease the time until emergence considerably as opposed to untreated seeds, with concentrations of 500-1000ppm GA3. Vegetative propagation involves several methods. Softwood tip cuttings strike relatively easily. Hormone gel or powder reduces the time taken to form roots. Leaf cuttings are an easy and fun technique and we have a blog post on it here https://herbalistics.com.au/takeaway-tek-psychotria-leaves-easy-propagation-method/.
Notes on my Psychotria hybrids: I have been successful in breeding two interspecific hybrids between Psychotria carthagenensis and Psychotria viridis, which I have named Nexus and DW02 (DW is my initials and is simply a way I can keep track of hybrids). I initially produced the Nexus hybrid in 2007 and assumed it was going to be a one off, so I actually gave a name to the hybrid, not realising over the next 13 years that I would have 120+ (and counting) new seed grown hybrids and breeding lines of Psychotria carthagenensis x Psychotria viridis. Nexus is therefore DW01. DW03-DW60 are generally backcrosses (though not all) between Nexus and P. viridis ‘Shipibo’ or ‘UDV’. Hybrids DW61-DW120+ are crosses between the DW series or open pollinated seedlings from these. This is a long term project!
An idea to breed the two separate but closely related species together (called an interspecific cross) came about via an obscure reference in a research paper (now lost to me) that the two were able to be hybridised. Since the flowers of P. viridis were so extremely small and hard to emasculate (remove anthers), I had better success using P. carthagenensis as the female (pistillate) parent and P. viridis as the staminate (male) parent. My initial breeding aim was to increase the cold tolerance and geographical range over which P. viridis (as an ayahuasca additive) could be grown, since P. carthagenensis was a much hardier species. This has been proven as Nexus is now successfully grown in many locations along the east coast of Australia and indeed around the world, in areas where P. viridis may have been very slow or struggled.
I’ve found it extremely rewarding to breed these plants, even though each new seed grown plant can take 1-2 years from seed before it is ready to evaluate and propagate. I feel as though they are my children and I learn to recognise them as only a parent can. Each has its own unique personality and appearance. Some are more vigorous than others, leaf shape varies widely, as does height and habit. The chemical constituents also vary and we have recently funded (2023-2024) a research project with NICM at Western Sydney University, focussed on legally analysing and identifying superior alkaloid producing cultivars. These plants will be available in 2024-2025.
Well that’s it, I hope this guide will help you to look after your Chacruna plants and make them as healthy as possible!