CSA-Journal-2016-04

years. During this time they are fully heterotrophic
and live from the mycorrhizal
fungus. Recently the term mycoparasitism
appears in the literature for this situation,
which is more commonly known as mycotrophy
and was in the past wrongly defined
as saprophytism. The exploitation of the
fungus through the orchid works so well
that sometimes the switch to autotrophy,
i.e. the development of green leaves above
ground, is fully omitted by certain species.
Previously ZIEGENSPECK (1936) mentioned
that neoteny is occurring in leafless
terrestrial orchids, i.e. their morphology remains
at an early juvenile stage, the mycorrhizome,
but they form flowers and reproduce
sexually. BURGEFF (1932) gave an
early broad overview of those orchids that
are fully mycotrophic and those, that are
in-between, i.e. orchids that form extensive
mycorrhizomes without long roots but also
green leafed stems above ground.
After this digression into the dry field
of physio-morphological orchidology let us
come back to the cymbidiums. Here we find
a broad range of germination and development
phenomena. As hinted earlier on,
the large-flowered subtropical to tropical
species (e.g. sections Cyperorchis and Floribundum)
usually develop no mycorrhizomes
or briefly show just very short ones
that quickly grow roots and leaves. Only
when the protocorms or short mycorrhizomes
of these species are kept constantly
in the dark they will grow into large mycorrhizomes
over time. All species of section
Jensoa, however, of which the germination
is known, always developed rather longlasting
mycorrhizomes, whether kept in
light or in the dark. One very rare species
in cultivation, Cym. macrorhizon LINDLEY,
1833, (Figure 6) is obligate mycotrophic
and retains an elongated mycorrhizome
for its entire life, never developing leafed
shoots. It has a wide distribution from Pakistan
in the west to Japan in the east and
lives underground in temperate to warm-
Fig. 6 Cym. macrorhizon cultivated in Japan.
Photo by K. Karasawa
temperate or subtropical forests. Only during
flowering and fructification is its presence
noticeable. This species has flowers
very similar to the wide-leafed Cym. lancifolium
HOOKER, 1823. It is interesting
to note that there are intermediate forms
with mycorrhizomes and leaves in varying
degrees, these are Cym. caulescens RIDLEY,
1915, and Cym. rhizomatosum Z.J. LIU et
S.C. CHEN, 2002, the latter likely a synonym
of the former. Cym. lancifolium also
shows a wide range of leaf development but
lacks a mycorrhizome in the adult stage,
as I can observe in plants we cultivate at
Hengduan Biotech (Figures 7 and 8).
Cym. goeringii and its close relative
Cym. tortisepalum FUKUYAMA, 1934, (often
treated as a synonym of the former but
clearly a distinct species) were sown by me
several times since 2002, and other species
like Cym. faberi and Cym. ensifolium as well.
The mycorrhizomes proliferate vigorously
(Figure 9) and can be easily separated into
many pieces, thus providing an easy means
21