Rostellum

The scolex of the organism is globular in shape and features a prominent projection known as a rostellum that is lined with a double row of hooks.

The splitting of the rostellum, curiously enough, never happens without insect aid; but if a bristle or needle be passed over it ever so lightly, a stream of sticky, milky fluid exudes, hardens, and the boat-shaped disk, with pollen masses attached, may be withdrawn on the bristle just as the bee removes them with her tongue. ❋ Neltje Blanchan (1891)

As nectar is already secreted for her in its receptacle, she thrusts her tongue through the channel provided to guide it aright, and by the slight contact with the furrowed rostellum, it splits, and releases a boat-shaped disk standing vertically on its stern in the passage. ❋ Neltje Blanchan (1891)

When the proboscis has reached the end of the spur, its basal portion depresses the little hinged rostellum that covers the saddle-shaped sticky glands to which the pollen masses (pollinia) are attached. ❋ Alfred Russel Wallace (1868)

It is to discover whether rostellum yet retains some of its primordial function of being penetrated by pollen-tubes. ❋ Charles Darwin (1845)

So in other cases, but I have not completely traced (only seen) that going to the rostellum. ❋ Charles Darwin (1845)

I did think it possible or probable that perfect fertilisation might have been effected through rostellum. ❋ Charles Darwin (1845)

By the way, Cephalanthera has single pollen-grains, but this seems to be a case of degradation, for the rostellum is utterly aborted. ❋ Charles Darwin (1845)

In Gymnadenia tridentata, according to Asa Gray, the anther opens in the bud, and the pollen being somewhat coherent falls on the stigma and on the rostellum which latter is penetrated by the pollen-tubes. ❋ Charles Darwin (1845)

Read Asa Gray in 2nd Review of my Orchis book on pollen of Gymnadenia penetrating rostellum. ❋ Charles Darwin (1845)

You can hardly imagine what an interesting morning's work you have given me, as the rostellum exhibited a quite new modification of structure. ❋ Charles Darwin (1845)

If you could prove what I only conjectured (from state of utriculi in rostellum and in stigma of Catasetum and Acropera) that the utriculi somehow induce, or are correlated with, penetration of pollen-tubes you will make an important physiological discovery. ❋ Charles Darwin (1845)

Asa Gray's observations on the rostellum of Gymnadenia are very imperfect, yet worth looking at. ❋ Charles Darwin (1845)

I want to know whether anything beats in modification the rostellum of Catasetum. ❋ Charles Darwin (1845)

I will say nothing about the rostellum, stigmatic utriculi, fertility of Acropera and Catasetum, for I am completely bewildered: it will rest with you to settle these points by your excellent observations and experiments. ❋ Charles Darwin (1845)

You know the membranous cup or clinandrum, in many orchids, behind the stigma and rostellum: it is formed of a membrane which unites the filament of the normal dorsal anther with the edges of the pistil. ❋ Charles Darwin (1845)

For the chance of your liking to look at what I have found: take a recently opened flower, drag gently up the stigmatic surface almost any object (the side of a hooked needle), and you will find the cap of the hemispherical rostellum comes off with a touch, and being viscid on under-surface, clings to needle, and as pollen-masses are already attached to the back of rostellum, the needle drags out much pollen. ❋ Charles Darwin (1845)