Parajubaea - Palms with Altitude
An in-depth look at all the species in this exiting
genus, slowly becoming more widely available.
by Imtiaz McDoom-Gafoor, London, UK
Chamaerops No.33 Winter 1998/99, published online 26-09-1999
Left: Parajubaea torallyi var. microcarpa, near
Potosi, Bolivia, at about 3200m.
Right: Parajubaea sunkha, near Vallegrande, Bolivia, at about 2500m.
There are three species of this beautiful, high altitude
palm from South America growing in the mountain ranges of the Andes
in Ecuador, Bolivia and Colombia. They are Parajubaea cocoides,
Parajubaea torallyi and Parajubaea sunkha . Although rarely grown
outside their natural habitat, they offer the possibility of growing
another pinnate leaf palm in the milder parts of western and southern
Europe which are not subject to temperature extremes.
P. cocoides is grown in Colombia and Ecuador between
2500 and 3000 m. elevation. It is only known from cultivated sources
and is possibly a cultivated form of P. torallyi. The cool Andean
climate sees little seasonal variation in temperature throughout
the year with day temperatures barely into the low 20's c., and
frosts occur at night. In Britain it has been grown to a 3 ft seedling
which succumbed to -5c (24f) in a London garden. However, it has
survived -8c (18f) in both Italy and northern California but was
completely defoliated so perhaps its lowest endurance is somewhere
between these two levels.
P. torallyi is widespread in Bolivia growing between
2700 and 3400 m. elevation. It is considered the hardiest of the
three species as it originates in a climate with more distinct seasonal
variation in temperate than Ecuador and also grows at a higher elevation.
The climate regularly sees lows of -7c (20f) in the Bolivian Andes
during the July and August winter months. Growing in sandstone mountains
at the unbelievable altitude of up to 3400 m makes this the highest
elevation palm in the world! It is possibly faster growing than
cocoides but is still rarely grown outside of South America.
Some similarities are found between cocoides and torallyi
such as habit. They both have smooth and tall stems, long petioles
and regularly arranged leaflets. There are also two forms within
the torallyi species - P. torallyi var. torallyi and P. torallyi
var. microcarpa, which differ in both fruit size and the shape of
the endocarp. They are restricted to steep inter-Andean valleys
where they grow amongst spiny vegetation between 2700 and 3400 m.
elevation. Here they are separated by several mountain ranges and
influenced by distinctive climatic conditions. A third species was
described as recently as 1996 - Parajubaea sunkha. "Sunkha"
refers to the abundance of fibres the palm produces which the local
people use for many purposes such as making rope and baskets. It
grows in dry valleys in semi-deciduous forests also in Bolivia at
the lowest elevation of the three species, 1700 up to 2200 m elevation.
It is unlikely to be in cultivation anywhere outside its natural
habitat and very little is known about it.
The potential of Parajubaea - particularly P. torallyi
- in a cool temperate climate such as mild coastal areas of Britain
and Ireland influenced by the Gulf Stream, northern Spain or parts
of western France lies in two areas. Firstly, its appearance gives
this palm an elegant, tropical look. The feather leaves are graceful,
wispy and arching, shiny green above, greyish white beneath, on
a tall, very slim trunk resembling Cocos nucifera, the coconut palm,
to which it is related. It is also related to Jubaea chilensis from
Chile which is reflected in its name - Parajubaea . More importantly,
it has a degree of frost tolerance, especially the Bolivian species,
which have a more leathery texture, perhaps an adaptation to its
The two biggest problems are firstly getting hold
of seeds and secondly germinating them. Cocoides seeds have been
available before and appear regularly in seed catalogues but torallyi
is much more difficult to obtain although the Seed Service does
offer them occasionally. The next problem is germinating them -
they have a low germination rate. It can take anything from six
months to several years.
The seeds of torallyi are extremely large and heavy
- bigger in size than an extra large walnut shell with three distinct
ridges. P. torallyi microcarpa, has much smaller, smoother seeds
with only faint ridges. The hard outer shell - the endocarp - contains
the endosperm from which the seedling germinates. It is important
to leave the whole seed, if fresh, in a warm, dry place for at least
two months before even attempting germination. This allows the endosperm
to loosen from its tough, outer shell and aids germination. The
seeds can be soaked in a weak fungicide for two days and then placed
just below the soil surface in a loose, open mixture, kept moist
in a warm place. It is also possible to break the endocarp with
a hammer or file down the extremely hard, wrinkly shell, making
several wedges in it to allow moisture to enter it to aid germination.
However, be warned that the hammer method may damage the endosperm
if the blow is too hard as I discovered myself with several crushed
seeds flying everywhere, which I promptly ate! The endosperm looks
and tastes like the flesh of a miniature coconut with a sweet, pleasant
taste and it is indeed often found for sale in the open markets
My P. torallyi seeds took about a year to germinate.
They are currently growing in a mixture of pure horticultural sand,
bark chippings and perlite in containers measuring six inches diameter
by sixteen inches depth - that's not a typing error, the containers
really are that deep. This is because once the seeds germinate they
send out a strong, penetrating taproot that goes directly downwards
before top growth commences. It is important that the seedlings
have a deep root run and as such specialised container sizes are
almost impossible to obtain, I'd visit a hardware store and buy
some plastic drainpipes. These are then cut to the length required,
with a bottom made up with drainage holes and filled with an extremely
free draining but moisture retentive mixture.
Apart from its unsuitability for container culture
due to its need for an unimpeded root run, the single root system
does not regenerate if damaged so it should never be transplanted
once planted out. However, this has to be weighed against its vulnerability
as a seedling in a cold climate and therefore a three or four foot
plant might be a good size to plant out, with winter protection
should prolonged freezes threaten.
Another limiting factor to successful cultivation
outside its natural habitat is excessive summer heat, and especially
hot or humid nights - day temperatures of 32c (90f) would be too
high. This palm is not adapted to tropical or sub-tropical climates
where it will rot and decline rapidly. The key is cool night temperatures,
which is crucial to strong, vigorous growth. It should be grown
in fertile, well-drained soil in full sun from an early age but
must be carefully acclimatised.
Once it germinates that's most of the battle won.
It grows remarkably fast and is easy to look after - not prone to
any pests - the seedling fronds are tough and leathery. Since germinating
each of my P. torralyii seedlings has produced three, lanceolate
leaflets. One robust seedling measured 2 ft long but only 2 ins
wide after only 12 months growth. Growth stopped indoors in late
October with decreasing light levels but they start showing signs
of growing again by early February. Its origins in a cool climate
is evident by its willingness to grow during the nights and in the
cold spring when temperatures are low. It is a pleasant change to
see a palm growing fast when others like Sabal or Syagrus only really
start growing when it is very hot.
Growth occurs rapidly after about three years, especially
if planted out and freed from the restrictions of pot culture. Cocoides
flowers and fruits after only twelve years in such diverse countries
as New Zealand and Italy, underlying its adaptability to Mediterranean
type climates. I've seen both cocoides and torallyi growing indoors
as young plants in the temperate house at Kew Gardens. They looked
identical although labelled differently. In general terms it is
possible to identify which species your seeds are by examining the
ridges on them. Both sunkha and cocoides have less obvious ridges
on the endocarp. Torallyi var. torallyi seeds have three prominent
ridges while var. microcarpa has three inconspicuous ridges.
A small Parajubaea is also planted outdoors at Kew
in the Duke's garden although it is very difficult to see in summer,
as there is a big, leafy tree in the way. It is easier to see in
winter as the tree is deciduous. It survived last winter's mild
temperatures without damage, helped by an extremely protected position
between two brick walls.
Parajubaea may never be available commercially in
Europe. The lack of seed, coupled with its erratic and lengthy germination,
and its dislike for pot culture, makes it an unsuitable choice for
nurseries demanding fast moving product lines. Purchasing seeds
will probably remain the best way to gain access to such a tropical
looking palm. It is another of those new, experimental palms from
high altitude mountain ranges of the world like Caryota 'himalaya'
and Ceroxylon - not yet assessed in colder climates but all requiring
similar growing conditions, that can endure moderate frost, can
thrive in cool summers and are highly ornamental.
08-12-19 - 20:30GMT
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