Mammillaria
scheinvariana
submerged
Bill Weightman recounts a visit to see Mammillaria
scheinvariana in habitat, before the entire site
disappeared under the water of a man-made dam.
Photography by the author.
20 Forest Way, St Mary Cray, Orpington, Kent, BR5 2AQ, UK
The Series Stylothele of the genus Mammillaria
contains a number of species that could hardly be
called the most spectacular of cacti but they are of
considerable interest to the Mammillaria specialist.
Several extra names have been created over the years
for species in this Series which have only minor differences
from their fellows and the taxonomic confusion
so caused raises many problems for the non-specialist.
“Fitz” and Betty Fitz Maurice of San Luis Potosi,
Mexico have studied this group of plants over many
years and their work has resolved many of these problems.
Any serious student is strongly advised to consult
their writings which have been published mainly
in the US Society’s journal but also in Arbeitskreises
für Mammillarienfreunde (AfM), the German Mammillaria
Society’s journal, and the journal of The
Mammillaria Society (GB).
But some of these species have calls to fame other than
their physical appearance and Mammillaria scheinvariana
is one of them. The construction of the Zimapan dam
in eastern Queretaro involved building the dam wall
across a narrow but very deep gorge and flooding the
valley system for miles upstream. Some parts of these
valleys had sheer precipitous sides, the scaling of
which would have daunted any but a skilled rock
climber, so what grew on them was quite unknown.
Over the ensuing years, as the water slowly rose, these
cliffs could be explored by using a boat. So it was that
M. scheinvariana was discovered by Rafael
Ortega and described and published by
Ortega and Glass in 1997. Therefore this
plant becomes, as far as I am aware, the
only cactus discovered by boat! Ortega
named it for Dra. Leia Scheinvar who had
co-operated with him in identifying plants
found during the operation.
I was fortunate in being able to take part
in one of these boating explorations in
1995. At this time the level of the water
was well on the way to reaching its maximum
height, having about a further
twenty metres to rise. The complicated
arrangements to make the trip had been
undertaken by Sr. Manuel Rivas, a gentleman
living in the nearby town of
Tequisquiapan. These arrangements
seemed to have involved dealing with just
about every official in the state! Our party
consisted of Manuel Rivas, “Fitz” Fitz
Maurice, Charles Glass, Derek Bowdery,
an official “guide”, the boatman and
myself. The authorities insisted that their
official guide came along with us and he
spent the day apparently quite bemused
by our activities. We were rather a large
party for a rather small boat and I tried to
forget the hundred metres or so of water
beneath us as we chugged slowly along
the margins of the lake.
M. scheinvariana had already been discovered
at this time but had not yet been described. This was due to some uncertainty as to the
identity of the plant. Some of the populations included
plants with hooked central spines while others did
not. It was eventually concluded that the plants with
the hooked spines were naturally occurring hybrids
with M. crinita which grows in the same area. “Fitz”
Fitz Maurice accepts the individuality of the new plant
but considers it a subspecies of M. crinita. It is a small
plant, about 5cm diameter and 2–3.5cm high and
forming small irregular clumps. The numerous radial
spines are hairlike giving the plant a shaggy appearance.
Central spines are not usually present but, if so,
are 9–16 mm long and straight, never hooked. (See
references below for a fuller description.) At first
glance the plant has quite a strong resemblance to
M. bocasana but a closer inspection revealing the
absence of hooked centrals is conclusive.
Now that the level of the water in the lake has reached
its maximum height, all the known sites for the plant
are submerged and, unless further populations are discovered,
it must be considered extinct in the wild.
Since this state of affairs was anticipated well in
advance, plants were collected and taken to the
CANTE Botanical Garden and propagated. In the following
year or so I saw many young plants in their
propagating facility. However, as is well known, it was
not possible to export these plants. With the demise of
the CANTE organisation the present whereabouts or even existence of these plants is unknown. A few
specimens are to be found in a couple of research collections
in Mexico and I have heard that plants have
recently been offered commercially in Europe. Its
continued existence in habitat depends on replanting
conserved plants in a suitable environment in another
canyon or, in the unlikely event of the present dam
ceasing to function, restoring it to its original site.
With such slender possibilities the future is bleak
indeed.
REFERENCES:
ORTEGA-VARELA, R. & GLASS, C. (1997) Guia para la Identificacion
de Cactaceas Amenazadas de Mexico. (Identification Guide to the
Threatened Cacti of Mexico). CANTE, A.C., Guanajuato, Mexico.
PILBEAM, J. (1999) Mammillaria The Cactus File Handbook No. 6.
p.260. Cirio Publishing, Southampton, UK.
FITZ MAURICE, W.A. & B. (1998) Cact. Succ. J. (US) 70(2): 88-94.
www.bcss.org.uk/scheinvariana.pdf