It is known from eight specimens, all found in China.

Its population is known only from a single, discovered specimen.

It is known only from a single specimen, a male.

Although known since 1887, it has only been described from male specimens.

It is known from eight specimens, with the most recent collected in 1980.

The species was described in 1895 from a single female specimen.

It is known from only a single specimen, collected in the 1950s.

All but one of the described species are known from fewer than 10 specimens.

In general, the family is considered rare, with close to 95% of the species known to have been described from single specimens.

Tissue culture can often help to produce many plants from just a few specimens.