Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/136

convex in front and concave behind, with its sharp summit slightly hollowed out on each side; it arches over the stigmatic surface (fig. 18, A, r, s). Internally,

Fig. 18.

Listera ovata, or Tway-blade. (Partly copied from Hooker.)

col.	summit of column.
a.	anther.
p.	pollen.
r.	rostellum.
s.	stigma.
l.	labellum.
n.	nectar-secreting furrow.

A.Flower viewed laterally, with all the sepals and petals, except the labellum, removed.

B.Ditto, with the pollinia removed, and with the rostellum bent down after the ejection of the viscid matter.