222 Sargent.—Fragments of the Flozver Biology 
beaks into the thistle-like heads of D. floribunda , R. Br., and D. carduacea , 
Lindl. 
Entomophilous Flowers 
now claim some attention. Though Lepidoptera are numerous here, I do 
not yet know for certain even one species of plant chiefly pollinated by 
either butterfly or moth: indeed I have observed extremely few visits 
of these insects to any flowers. On the rare occasions when I have seen 
a butterfly visit a flower it has seemed useless as a pollinator. The flower 
of Stackhousia Brunonis y Benth., seems to be specially adapted for moths. 
The corolla is a longish tube, and at night it exhales a most delightful, 
Narcissus-like perfume (Mr. C. R. P. Andrews first called my attention to 
this fact). The flower is yellow or tawny in colour, and does not seem 
particularly visible at night. 
Indigenous Hymenoptera visit many flowers ; but only in one case 
have I definitely connected one with a flower as official pollinator. The 
Orchid Caladenia Barbarossae , Reichb., is visited by a large black wasp, 
whose name I have not yet ascertained. The labellum of this Orchid is so ar¬ 
ranged that when the wasp alights on the lamina it swings forwards towards 
the centre of the flower. This movement brings the wasp’s back forcibly 
into contact with the stigma, whose secretion renders a circular patch of 
the wasp’s back sticky. When the insect seeks to leave the flower, one 
edge of the sticky patch comes in contact with one or more of the disc-like 
pollinia peeping from the anther just above the stigma. Even momentary 
contact serves to attach the edge, and the whole disc is withdrawn from 
the anther as the wasp’s egress continues. When withdrawal is complete 
the pollinium falls upon and exactly fits the sticky patch on the wasp’s 
back. Obviously the next flower visited will receive upon its stigma 
a liberal supply of pollen. A full account of my observations will be 
found in ‘Journal W. A. Nat. Hist. Soc.’, No. iv (Nov. 1907). At that 
time I had not determined what is the attraction of the flower. Sub¬ 
sequent investigation has, I think, revealed it. The central labellar 
appendage, which the wasp seizes with its mandibles, seems to be a true 
gland, secreting nectar so slowly that crystallization takes place practically 
simultaneously. In one instance I found the crystals aggregated into 
tiny globular masses much resembling raspberries as I viewed them against 
the purple skin of the gland. The crystals appear to be sucrose. An 
amorphous sticky substance (glucose ?) is also present. My investigations 
are at present very far from complete; but I have reason to believe that 
the peg-like calli of all species of Caladenia and allied genera secrete 
similarly. I have never yet found them gnawed by insects (excepting 
cases where a large portion of the labellum has been damaged—evidently 
not by a pollinator): I believe they are simply ‘ licked ’. The genus 
Drakaea is highly interesting. 
