Parajubaea torallyi is a handsome hardy palm from South America. However, it is rarely cultivated by gardeners outside its natural habitat, Bolivia, due to its large seeds (which means high shipping costs).
Native to Bolivia, it grows in the dry and dusty, inter-Andean valleys in an altitude of 2700–3400 m above the sea. Therefore, this palm is the highest elevation palm species to occur anywhere in the world. The temperature rarely rises above 20 °C and night frosts are not rare in this altitude. The temperature often falls to as low as –7 °C during winter months (July and August) and the annual rainfall is only a mere 550 mm.
Its tolerance to drought, heat, cold, frost, and other adverse conditions, and its ability to maintain a great appearance, causes some to say that this legendary palm not only has enormous potential as an ornamental, but that it could become one of the most desirable landscaping palms for warm temperate and subtropical areas In areas were frost may occur it requires winter protection or keeping in frost free environment. It is reported that in Europe it is frost up to a temperature of –3°C. The lowest temperature which this palm has survived in cultivation was –8 ° C. These plants lost all their leaves, but survived and in springtime, new leaves appeared!
In Bolivia, this palm grows up to 14 m tall with a trunk 25–35 cm in diameter. Palms which are 100 years and older, grow to over 30 m tall with a trunk diameter of 50 cm. A nice crown has round about 20 leaves and some of them are up to 5 meter long! Plants grown outside Bolivia are however smaller.
There are two distinct populations in the natural habitat that differ mainly in fruit size and have recently been described as two distinct varieties, the small-fruited P. torallyi var. microcarpa and the large-fruited P. torallyi var. torallyi. Whilst not significantly different in appearance, var. microcarpa does not reach quite the dimensions of its large-fruited cousin, but in terms of adaptability and robustness, it falls nothing short of it. The seeds have an unfair reputation of being unreliable to germinate. Although germination can be somewhat erratic, the seeds will eventually sprout quite easily when sown under proper conditions, i.e. on the surface of seedbeds, buried only halfway, and kept slightly moist. With proper care, in a cool to mild subtropical climate and a sunny place, seedlings will quickly develop into tall, robust-trunked palms with large, shuttlecock-like crowns of finely pinnate, leathery leaves.
Parajubaea torallyi is a popular ornamental plant and it is often grown in parks and on sidewalks. In Ecuador and Southern Colombia, the Parajubaea cocoides is often grown where the altitude is 2500 to 3000 meter – this is a slow growing palm with less frost tolerance. As it is quite similar to the Parajubaea torallyi and as its natural habitat is not known, it is accepted that it is a cultivar of the Parajubaea torallyi.
The smallest of this palm species is the Parajubaea sunkha which has been described in 1996. It only grows 8 meters tall and occurs in the Andean valleys in the region of Vallegrande, in the district Santa Cruz in Bolivia where the altitude is 1700–2200 m. It has always been incorrectly identified as Parajubaea torallyi until recent taxonomical research was done and it was renamed to Parajubaea sunkha.
Palms of the genus Parajubaea are easy cultivated palms. The best growing method is by using seeds. However, you need to be very patient as seeds sprout very slowly and unevenly in the wild, and it takes about one and a half years to do so. Some seeds start to germinate within a month, but others takes a year or even two years to start sprouting. As it is a subtropical palm species, it is better to keep them in a lower temperature, as in a higher temperature (unlike in the case of other palm species) which may have a negative influence on the germination process. High temperature indicates dry periods, which is not fit for germination.
Before sowing, seeds should be put in water with a temperature of about 20 °C for around 5 to 7 days. Seeds of the big-seed variety should be kept in water for around two weeks. The water should be changed every day. Seeds could also be scarified to allow for better germination.
The soaking of the seeds in the water will conclude the dormant period and will inaugurate the rainy season, which is the most suitable season for germination. Dormancy protect seeds not to start sprouting during the dry season in Bolivia (the winter in June to October)
After soaking, the seeds should be sown into a pot or plastic bag – take care that just half of the seed is covered with soil and keep them at a temperature of 10 to 20 °C.
A positive influence on good germination is the difference between day (high) and night (low) temperatures. Once the seeds are sown, they should not be watered too much as too much water may destroy young plants. The main difference between the cultivation of Parajubaea and other palm species is the lower temperature it requires as well as less water.
After sowing, seeds should be checked every three to four weeks and sprouting seeds should be kept in individual pots. Some palm growers give the following advice regarding seeds that do not sprout within six months: Stop watering the seeds and let the soil dry out for few months. Take the seeds out of the soil, put them back into water for around a week and then sown them again.
These seeds should start sprouting within the next half a year. If some of the seeds still do not sprout, repeat the process and all remaining seeds will sprout after the next rain season.
The germination rate of Parajubaea seeds is almost 100%, you just need to be patient enough, and allow a dry season for those lazy seeds!
Once you have a young palm, it is hardy, but keep in mind not to water it too much. A young palm prefers a moderate environment (in their natural habitat they grow under the shade of the adult palms), however older plants requires a sunny position.
Genus Parajubaea is one of the most endangered South American palms. The main reason for this being the destruction of natural habitats, spreading of the agriculture lands, wood mining and overgrazing by cattle. These palms occur in a very small area, which make the treatment much more serious and has the risk of extinction. Due to the large seeds of these plants, their spreading ability is also limited. The most important animal helping these palms to spread to new areas is the Spectacled Bear (Tremarctos ornatus), however these animals are also threatened by human activities.
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