22
A THREE-SPURRED FORM OF THE LARGER
BUTTERFLY ORCHIS (Habenaria chlorantha Bab.
var. tricalcarata Helmsley)
By G. LISTER.
THE Club's herbarium at the Essex Museum contains
several fine typical examples of the Larger Butterfly
Orchis, collected in various places. Amongst them, on a sheet
marked "ex-herb. Wm. Moore," is a remarkable variety, col-
lected in May 1893, in Braintree Green Wood. Instead of
the usual long lax spike of large white flowers, this specimen
has a dense spike of about fifteen rather small greenish-white
flowers, all of which differ in construction from that of the normal
form.
The typical Larger Butterfly Orchis has a broad upper sepal,
two long spreading lateral sepals, two narrow petals ascending
on either side of the upper sepal, while the third petal forms a
long greenish-white lip with a slender tubular spur, containing
honey and twice as long as the lip. In Mr. Moore's specimen,
the upper sepal and two lateral petals are alike and narrowly
triangular; the lateral sepals resemble the lip in all respects,
except that they are shorter; each is provided with a long
honey-bearing spur; the single stamen appears to have had
Well-developed pollinea with sticky discs, diverging even more
than usual from each other, as they lie above and outside the
openings into the three spurs. The stigma does not seem to
have been functional; no trace of ovules was found; more-
over, the ovary has not the usual twist, so that the spurs
of the flower are directed more or less upward, instead of down-
ward.
This strange variety appears to be very uncommon. A similar
specimen, found near Sherborne, Dorset, in June 1906, was
described and figured by W. B. Hemsley in the Journal of the
Linnean Society, Bot., 38, p. 6, pl. 1, as a new variety, Platanthera
chlorantha Custor var. tricalcarata. In the same volume, Mr.
Hemsley described another three-spurred form of the Butterfly
Orchis, found near Bath about the year 1902; but the flowers
in this have the lateral petals, not the lateral sepals, provided
with long spurs (op. cit., p. 391, figs. 1, 2.).