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genus Copiapoa is endemic to Chile and is found in the arid
north of the country between the latitudes of 22°S and 31°S. Rain
in this region is a rare phenomenon and sporadic, falling mostly
every 5 to 7 years in a weather pattern known as "El Niño". Most
Copiapoa species inhabit coastal regions where the plants
gain most of their moisture from the ‘camanchaca’, the local name
given to the mist which rolls in off the Pacific Ocean.
Copiapoa is a very successful genus in this harsh environment
and is often the dominant plant within the flora of the region.
They are well adapted to the arid conditions; being able to retain
moisture during the long periods of drought. Some species have an
extreme waxy coating on the epidermis to reduce water loss
further, others have evolved a geophytic lifestyle with most of
the plant at .....
[P...]
..... and below ground level. Copiapoa is a genus which is
very distinct within the cactus family but for which it has been
difficult to pin down a classification at the species level. One
problem is in the similarities of the flowers, fruits and seeds.
This leaves us largely dependent on vegetative characteristics to
determine relationships but these are less reliable and often
affected by the extreme environmental conditions under which the
plants live.
One species which is well known and common in
cultivation is Copiapoa humilis. It is one of the small
growing soft bodied species which survives the aridity in habitat
by possessing a large tap root in which it stores moisture. Unlike
many Copiapoa species it grows rapidly from seed and at 3
or 4 years of age it can begin flowering. Hence its popularity in
the greenhouse. However the scope of this species is not well
known and this article aims to document and illustrate the various
subspecies which are now recognized.
Figure 2 The habitat of Copiapoa humilis
subsp. humilis;
hills above Paposo, with camanchaca mists rolling in off the
sea
What we now call Copiapoa humilis was
originally described by Dr. Rudolph Philippi in 1860 as
Echinocactus humilis. The description is not particularly good
and lacks illustrations. The plant was unfamiliar to the authors
Britton and Rose some 60 years later while writing their four
volume "The Cactaceae", so they did not include it in their new
genus Copiapoa (The Cactaceae, 1922), although they
suspected it belonged there. However Philippi recorded the type
location accurately as Paposo, a small fishing village in the
province of Antofagasta. Nearly 100 years after its first
description Paul Hutchison, whilst visiting Chile, returned to the
type locality and collected material. He then published a much
improved description and made the combination in Copiapoa.
The explorations of Friedrich Ritter in the
1950s and 60s did much to extend our knowledge of the genus
Copiapoa and many new species and populations were found by
him. He tended to favour the rank of species for every new
population, whereas more recently the consensus has been to use
the rank of subspecies to group together closely related taxa. The
present concept of C. humilis includes a number of Ritter’s
species reduced to the level of subspecies. The distribution of
Copiapoa humilis is very interesting as it occurs in small
disjointed populations over a wide area. Our knowledge is most
probably incomplete and intermediate populations may be found
which may complicate matters. However until that time I consider
the separate populations are worthy of naming at the rank of
subspecies, which in some cases has already been done elsewhere. I
presently accept 7 subspecies, one of which is described here for
the first time, and one which is still in need of a formal
description. Finally two taxa which have been considered as
varieties of C. humilis by various authors are referred
elsewhere.
