Horti Selbyani: Pursuing a Purple Passion-Caucaea: A Perspective from Greenhouse and Field

2006·1 MB·

by  Zelenko, Harry

Selbyana 27(1): 88-92. 2006.
HORTI SELBYANI
PURSUING A PURPLE P ASSION-CAUCAEA: A PERSPECTIVE FROM
GREENHOUSE AND FIELD
HARRY ZELENKO
P.O. Box 17-22-20043, Cumbaya, Quito, Ecuador. Email: [email protected]
When considering Caucaea olivaceum (for Trade in Endangered Species of Wild Fauna and
merly known as Oncidium cucullatum), the Flora) permit. My application was refused by the
question arises, are there the many species sug CITES officer in Ecuador, but I will appeal the
gested by John Stacy (1975) and echoed by Eric decision. Oddly, cut flowers can be taken across
Christenson (2000), or do only a few species international borders without a problem.
exist with many geographic varieties? If you DNA sequence analysis by Norris Williams,
think I know either as fact, I do not, but I tend Mark Whitten, and Mark W. Chase (2001) has
toward a few species. demonstrated that Caucaea does not differ ge
Based on the 15 years I have spent collecting, netically from other species in the Cucullatum
growing, studying, and illustrating Caucaea section of Oncidium. Since Caucaea is the older
plants and their flowers from many areas of Co genus name, it has priority.
lombia, Ecuador, and Peru, I am familiar with Although Lindley described and named On
Caucaea olivaceum plants and their remarkably cidium cucullatum in 1838, an older name for
beautiful flowers in all hues of purple-a color this species, Oncidium olivaceum, was published
beloved since my childhood. These diverse col by Kunth in 1816 for a plant collected by Hum
ors suggest to me that the plants might very well boldt and Bonpland.
be a singular species with varieties. As a grower, I suspect that the genus is lim
Not being a taxonomist, I am bothered by the ited to no more than the seven species listed be
number of named species based on minor dif low. It is possible that more species will be dis
ferences. I have been informed that the lip callus covered and described in the future, and it is also
is not a definitive feature in defining a species possible (even probable) that with molecular
(M.W. Chase pers. comm.). Although the callus studies, we might learn that some of the plants
can be different in Caucaea olivaceum flowers that are today called species will turn out to be
in Colombia and Ecuador, and the color, size, geographic varieties.
and form can vary from plant to plant in differ • Caucaea radiata (Lindl.) Mansfield is a rather
ent locations, they share undeniably similar small plant with diminutive white and brown
characteristics (FIGURE 1). flowers. Found in Colombia at 2400 m, it is
DNA analysis may provide the answer. Since a cool-growing epiphyte that blooms in spring
the laboratory equipment needed for DNA anal and early summer.
ysis of Caucaea is available at the 10drell Lab • Caucaea olivaceum (Kunth) N.H. Williams &
oratory, Royal Botanic Gardens, Kew, I placed M.W.Chase, synonym C. cucullata (Lindl.)
14 different Caucaea specimens (flowers or leaf N.H.Williams & M.W.Chase, is a widespread
parts) in sealed bottles with silica gel and ap group of populations that occur primarily in
plied for a CITES (Convention on International Colombia and Ecuador. Having had so many
88
HORTI SELBYA NI 89
FIGURE 1. Paintings of Caucaea flowers by Harry Zelenka from Orchids: The Pictorial Encyclopedia of
Oncidium (Zelenka et al. 1997).
specimens in cultivation from different loca in Colombia." He gave species status to On
tions over the years, and despite their differ cidium olivaceum var. gigantium but then
ences in color, pattern, size, fonn, and callus, qualified it, stating that when more informa
it is my opinion that, for the most part, they tion becomes available "It may prove to be a
are simply varieties. In his monograph, Stacy distinct species." On the basis of callus dif
(1975) listed Oncidium olivaceum as a syno ferences and flower part measurements, he
nym to O. cucullatum subvar. olivaceum has given species status to Oncidium kenne
based on a slight dimensional difference of dyi, O. cucullatum var. dolabratum, O. cucul
the callus, noting that he had "not seen any latum var. macrochilum, and O. rhodostictum.
material of this species outside the Cauca area At the time that Stacy visited Ecuador and
90 SELBYANA Volume 27(1) 2006
FIGURE 2. A large flower drawn to the size it was found in the field. When the plant was brought into
cultivation, a smaller flower opened on a secondary inflorescence on the same spike. This flower, about half the
size of the original flower, is sometimes called "Oncidium kennedyi."
Colombia to research his 1975 monograph, very also occurs in Venezuela. Caucaea mimetica
few roads existed, compared with today. New has a different shape and callus from those of
roads now provide access to previously unex C. olivaceum. Again, defining the difference
plored areas, and new populations of Caucaea by callus alone may not be valid. Flowers of
have been and are, even now, being discovered. C. mimetica, however, seem to differ in shape
Cultural conditions vary from valley to valley from C. olivaceum. The callus structure ap
and mountain to mountain; and when a popula pears to be similar to C. sanguinolenta. We
tion is isolated over many generations, details of know with other orchids that flower shape can
the flowers can vary from population to popu vary from population to population within a
lation. With the lip callus not a definitive ele singular species, and thus the question arises
ment in determining a species, we all know that about C. mimetica as well. DNA analysis
flowers can vary in dimension from plant to might meld them into one species, or else de
plant and even on the same inflorescence (FIG fine the difference between them.
URE 2). e Caucaea nubigena (Lind!.) N.H.Williams &
• Caucaea sanguinolenta (Lind!.) N.H.Williams M.W.Chase is primarily from Ecuador. It has
& M.W.Chase is a species from Colombia and widespread populations and has been given a
perhaps Ecuador with colors that range from number of different species names. All of the
white with pale pink spotting on the lip to a populations I have observed, however, seem
deep rose/magenta with purplish spotting. The to me to be a single species, though they are
method of inflorescence of these plants differs extremely variable in color and shape, not un
from that of Caucaea olivaceum in that the like C. phalaenopsis. Stacy gives measure
flowers emerge from an undeveloped new ments of flower components, yet, as noted
growth, while C. olivaceum flowers emerge above, every grower knows that dimensions
from a mature pseudobulb. Stacy, however, of flowers and their petals and lips can vary
had a limited view of populations in the field within any species of orchid. I therefore sug
and had not grown either plant. Although their gest that what Stacy calls C. alticola, C. tar
calluses vary, it remains to be seen if the two quiense, C. aequinoctiale, C. erosilabium, and
are different genetically. C. chimborazoense should be treated as syn
• Caucaea mimetica (Stacy) N.H.Williams & onyms of C. nubigena-geographic varieties
M.W.Chase is a species from Colombia that again.
HORTI SELBYA NI 91
• Caucaea phalaenopsis (Linden & Rchb. f.) florescence; and when plants are moved to a new
N.H.Williams & M.W.Chase from Peru and environment, emerging flowers may also change
southern Ecuador is an extremely variable in size because cultivated plants obviously do
species, exhibiting variation in shape, lip size, not receive the same conditions that nature pro
color, and pattern from flower to flower. This vides. Some of the Caucaea plants I currently
species includes unusual and distinctive color am growing from high elevations produce small
forms, including some with chartreuse sepals er flowers when moved into our greenhouse. Ul
and petals, pink lips, and no spotted pattern. tra-violet deprivation caused by the plastic roof
Most of the flowers I have seen, however, ing may be the reason, even though the plants
have purple and/or magenta spotting on the get better general care in cultivation than in the
tepals and lip. Just because flowers from dif field. We have moved some of the plants out-of
ferent areas (or different trees) have different doors and are waiting to see whether the flowers
markings, and no two are exactly alike, we will be larger, as they were when these Caucaea
cannot put species names on the hundreds plants were collected.
(perhaps thousands) of color and pattern var The question remains; how does one define a
iations. In his monograph, Stacy (1975) notes species? If flowers in a popUlation have varied
in the botanical key to species that Oncidium colors, shapes, patterns, callus sizes, and fra
dayanum and O. spathulatum differ from O. grances, and if the inflorescences vary, what
phalaenopsis with suggested differences in then is the definable difference? Christenson
their calluses. With other taxonomists holding (2000) has quoted much of Stacy's monograph
that the callus is not a defining characteristic with little original taxonomy and states that Cau
in itself insofar as distinguishing a species, I caea are all small plants. I am growing Caucaea
doubt Stacy's contention. With other growers olivaceum plants with pseudobulbs measuring
in Ecuador, I believe that what Stacy listed as nearly 5 inches in height with leaves nearly a
O. dayanum and O. spathulatum are simply foot in length.
synonyms of C. phalaenopsis. Stacy has in According to Christenson, the callus, along
cluded O. tripterygium in his lexicon of spe with the number of leaves to the pseudobulb, the
cies, although he admits only seeing a single dimensions of the lip, the color schemes of the
pressed flower "in a rather poor state of pres flower, and the overall measurements of the flo
ervation, " again claiming the callus differs ral segments are the elements. Not being a tax
from O. phalaenopsis. onomist, it is difficult for me to refute his list of
• Caucaea andigena (Lindl.) N.H.Williams & criteria; but having spent time in the field and
M.W.Chase is a small yellow-flowered species grown so many Caucaea plants, among my fa
from southern Ecuador. Stacy notes seeing vorites in Oncidium (because of their purple col
only one flower on a type sheet in addition to or), I have seen almost all of Christenson's cri
John Day's painting. He failed to note that this teria vary from flower to flower and plant to
is the only Caucaea having almost all yellow plant, even within the same population. For in
flowers with a touch of lavender. He did note, stance, I have grown a C. olivaceum with flow
however, that the callus is similar to that of ers that had a "double" callus. Despite this ab
C. sanguinolenta. This may be a color variety erration, this flower was identical to others col
and not a separate species. According to Dod lected from the same population at the same
son, Caucaea sanguinolenta, although known time in all other aspects. I don't think such an
from Colombia, is also found near Cuenca, aberration makes a new species any more than
Ecuador. a person born with six fingers is no longer Homo
sapiens.
Stacy described separate species partly based I am, to say the least, confused by the existing
on the type of inflorescence . . . a plant with a taxonomy on Caucaea and think DNA sequenc
straight raceme became one species, a zigzag ra ing will provide answers to some (even most) of
ceme another, and branched still another. I find the current questions. With the addition of field
this rather difficult to believe, because, in my observation, we may learn more about this beau
greenhouse, I have had a large plant of Caucaea tiful group of orchids rather than having to rely
olivaceum with all three of these forms of inflo on the guesswork and intuition of armchair tax
rescence. This is what triggered my questioning onomists.
the number of different species that have been
described in the past. Also, within a single pop
CULTIVATING/RESCUING CAUCAEA
ulation of C. olivaceum found near Machachi,
Ecuador, all three forms of inflorescence occur. A move from New York City to Cumbaya, a
We know that in cultivation, and in the field, suburb of Quito, Ecuador, located at 2300 m,
a flower can vary in size, even on the same in- provided advantages for the growing of or-
92 SELBYANA Volume 27(1) 2006
chids-no more heating and no more air con trees that housed orchids become depleted and
ditioning (Sorry, Con Ed). The night tempera even disappear over a period of a few years (or
tures here in Cumbaya, where we grow many less), because of slash-and-burn agriculture.
Caucaea plants, average 50oP; and the day tem When we see this happening, we rescue as many
peratures usually peak in the low 80s, sometimes plants as we can carry. This has happened with
higher; and, of course, lower when the day is one large population of Caucaea olivaceum that
gray. This area of Ecuador really has only two we are now CUltivating. When trees are cut to
seasons-wet and dry. The Quito area is rather make space for a potato field or to feed a few
dry, so I water almost every sunny day. Other cows on secondary growth for a limited period
wise, an automated fogging system compensates of time, thousands of orchids (even millions) can
for dryness by emitting clouds of humidity ev be destroyed. I believe it is time to get govern
ery few minutes during the day. Humidity, of ment involved in convincing poor farmers that
course, rises naturally at night. The greenhouse, they may be able to earn more money by means
designed for high-elevation plants, remains open of eco-tourism by leaving orchid-laden trees
with "walls" of nylon netting stretched on rather than by chopping them down to clear
frames around the perimeter to keep out insects short-lived cropland.
and provide natural temperature and air circu
lation.
ACKNOWLEDGMENTS
The roofing material is a special double-wall
plastic called Sun Stop, claimed by the manu I thank Eduardo Sanchez and Alexander Hirtz
facturer to block ca. 40% of the heat and light for their assistance and Calaway Dodson, Ed
of the sun (which is extremely strong here on uardo Sanchez, Hirtz, Stig Dalstrom, and Mark
the Equator). Additional shading is provided for W Chase for their insights, comments, and ed
Caucaea olivaceum plants, because in their nat iting.
ural habitat, they were shaded by the leaves of
their host trees. We grow them in pots or baskets
LITERATURE CITED
or on cork slabs or logs with sphagnum around
the roots. Many varieties of Caucaea nubigena
Christenson, E.A. 2000. Hooded oncidiums. Orchids
and C. phalaenopsis also are in cultivation. I try (Arner. Orchid Soc.) 69(10): 952-960.
to replicate natural conditions for them, based Stacy, J.E. 1975. Studies of the genus Oncidium. Har
on my field observations. My wife Rosemarie vard Bot. Mus. Leafl. 24(7): 133-191.
and I must be doing something right, because Williams, N.H., M.W. Chase, and W.M. Whitten. 2001.
the plants are growing well, and some remain in Phylogenetic positions of Miltoniopsis, Caucaea,
flower for months at a time. a new genus, Cyrtochiloides, and Oncidium phy
matochilum (Orchidaceae: Oncidiinae) based on
Some people have questioned us about col
nuclear and plastid DNA data. Lindleyana 16:
lecting plants from the field. Formerly, we took
272-285.
only one or two specimens, leaving the popu
Zelenko, R., B.D. Zelenko, and M.W. Chase. 1997.
lation to continue in nature; however, we have The Pictorial Encyclopedia of Oncidium, ZAl
seen more than one forest here in Ecuador with Publications, New York City.