Chen Sing-Chi
J Syst Evol. 1979, 17(1): 1-6.
Diplandrorchis is a very curious new orchid genus, containing only one species D.
sinica S. C. Chen, found in Huan-ren County of Liaoning Province in northeastern
China. It, as the genus name implies, has two fertile stamens, borne on the upper
part of the column near the terminal stigma. One of them is opposite to the dorsal
sepal, while the other to the median petal (lip). Thus, they represent two median
stamens of both inner and outer whorls. This is quite unique in the whole family,
including the diandrous group, in which the two stamens are opposite to the lateral
petals and thus represent the lateral ones of the inner whorl.
The flower is erect, with its pale greenish or whitish perianth nearly regular.
Two lateral sepals are more or less oblique, showing some difference from the dorsal
one, but the three petals, which are thinner and narrower, are very similar to each
other. Neither rostellum nor any other appendages are found in its column, but a
terminal stigma and two erect stamens. The pollinia are naked and granular, which,
in almost all flowers examined, have naturally fallen out of their cells on to the stigma.
Apparently, it is self-fertilised, as found in Tangtsinia and some other primitive
orchids.
Besides, this interesting orchid is a dwarf saprophyte, with its habit very similar
to that of Neottia, another saprophytic genus assigned to the subtribe Neottiinae. The
fact that the saprophytic orchids are largely found in the primitive subtribes, such as
the Neottiinae, Limodorinae, Vanillinae and Pogoniinae, is worthy of special attention.
Theoretically, the saprophytic plants must have developed from green-leaved plants. In
the Orchidaceae, however, what ancestor are the most primitive saprophytes derived
from ? This is indeed an interesting question closely related to the origin of the
Orchidaceae.
From the facts mentioned above, the present genus is a very primitive or relic
one and of great phylogenetic interest. It is placed here as the most primitive member
in the subtribe Neottiinae, although it is sharply distinct from the remaining generaof this subtribe. It may deserve a separate subtribe, but further study is needed.
