s stigmatic all over, inside and out, with a transverse
band of short glandular hairs at its base outside, while the lower more
prominent lip is smooth and glabrous, or with a tuft of rigid hairs.
Perhaps this lower lip and the upper band of hairs are all that
correspond to the indusium of other genera; and the so-called upper lip,
outside of which impregnation may well take place, as observed by Mr.
Darwin, must be regarded as the true stigma."

Darwin's interest in the Goodeniaceae was due to the mechanism being
apparently fitted for self-fertilisation. In 1871 a writer signing
himself F.W.B. made a communication to the "Gardeners' Chronicle"
(590/6. 1871, page 1103.), in which he expresses himself as "agreeably
surprised" to find Leschenaultia adapted for self-fertilisation, or at
least for self-pollinisation. This led Darwin to publish a short note in
the same journal, in which he describes the penetration of pollen-tubes
into the viscid surface on the outside of the indusium. (590/7. 1871,
page 1166. He had previously written in the "Journal of Horticulture and
Cottage Gardener," May 28th, 1861, page 151:--"Leschenaultia formosa has
apparently the most effective contrivance to prevent the stigma of one
flower ever receiving a grain of pollen from another flower; for the
pollen is shed in the early bud, and is there shut up round the stigma
within a cup or indusium. But some observations led me to suspect that
nevertheless insect agency here comes into play; for I found by holding
a camel-hair pencil parallel to the pistil, and moving it as if it were
a bee going to suck the nectar, the straggling hairs of the brush opened
the lip of the indusium, entered it, stirred up the pollen, and brought
out some grains. I did this to five flowers, and marked them. These
five flowers all set pods; whereas only two other pods set on the whole
plant, though covered with innumerable flowers...I wrote to Mr. James
Drummond, at Swan River in Australia,...and he soon wrote to me that he
had seen a bee cleverly opening the indusium and extracting pollen.")
He also describes how a brush, pushed into the flower in imitation of
an insect, presses "against the slightly projecting lower lip of the
indusium, opens it, and some of the hairs enter and become smeared
with pollen." The yield of pollen is therefore differently arranged in
Leschenaultia; for in the more typical genera it depends on the growth
of the style inside the indusium. Del