NOTES ON THE FLOWERS OF ADENANDRA 
39 
glands, viz. staminal as well as staminodal, shows that the secretion does not 
contain any sugar, but that it is a kind of balsam, similar in its nature to the 
viscid coating of the flowers of some heaths, e.g. Erica blenna, E. regia, E. 
physodes (white sticky heath of Table Mountain), etc., and the viscid secretion 
of the glands on the leaves of Roridula denlata 1 . But while in these cases the 
viscid fluid affords protection against creeping insects it has quite a different 
function in the flowers of Adenandra. The flowers are strongly protandrous. 
When the bud opens the staminodes connive towards the centre of the flower 
and their glands are viscid, while the stamens stand erect outside of the 
staminodes, their anthers being still closed and the apical glands erect and 
dry (Fig. A, 2). Then one stamen after another, with an interval of a day or 
two, moves its anther towards the centre, the anther-cells split open, the 
apical gland reclines on the back of the anther and becomes viscid, w'hile the 
pollen is finally deposited on the top of the curved style, the stigma being at 
this stage undeveloped and pressed against the ovary (Figs. A, 4 and 7). 
When all the anthers have discharged their pollen, the secretion of viscid 
balsam ceases, staminodes and anthers shrivel up, the style begins to stretch 
itself until it is erect, and the stigma, large and fully developed, stands 
upright in the centre of the flower (Fig. A, 8). In Adenandra uniflora each 
flower requires several days or a week to complete this development, and it is 
obvious that the viscid fluid can serve only one purpose, viz. to act as an 
adhesive by means of which the pollen is firmly attached to the mouth-parts 
of the visiting insects while they force their head in between the stamens and 
staminodes in order to reach the honey in the base of the flower, thus com- 
pelling the visitor to carry the pollen to an older flower where the stigma is 
in its receptive stage. 
The elaborate structure of the flower and the complicated movements 
during its anthesis are consequently the means of securing the cross-pollina- 
tion of the flowers. 
As far as our observations go, all species of Adenandra are constructed 
on more or less the same plan, although some less elaborately than others. 
The number of insects actually observed by us on the flowers of various species 
is, however, very small — an experience recurring in numerous other groups. 
It is extraordinary that on bright sunny days one may be among patches of 
Adenandra uniflora with perhaps hundreds of its brilliantly white flowers 
and not see a single insect visiting them. However, we have observed two 
kinds of flies with long proboscis (Pangonia) and two beetles, vrz. Anysonyx 
Ursus and another one, and on one occasion also a bee, although such short 
tongued insects could not reach the nectar at the base of the flow r cr but w ould 
only gather the pollen. 
1 R. Marloth, Trans. Roy. Soc. S.A. 1910, p. 59. 
