The pollinaria may be removed from the flower with a needle and by design is meant to be removed whole and transported to another flower. The wave crest is a slit that runs along the surface of each pollinia . It is from this slit that the pollen tubes emerge. This resin-like organ is not grown but is secreted by glands just before the buds mature and usually hardens completely shortly after the flowers open. If an insect becomes caught by this slit it will lift the retinaculum , which are attached to two pollinia and thus carry off an entire pollinarium .
Guide rails .
A small hollow tube with a slit running its legnth would be an easy description for this structure. The guide rails often fill up with nectar, which may expedite the growth of pollen tubes. The stigma in Hoya is pentagon shaped when viewed from above and may be reddish or green. The only parts meant to be receptive are the five small spots that are at the end of the guide rails though the entire surface may be receptive. When cut the stigma does not ooze sap, unlike other parts of the plant.