Hyacinthus: an Insect Pollinated Species

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The common garden hyacinth (Hyacinthus orientalis) serves as a good example of an insect pollinated species.  Fig. a shows the familiar flower spike carrying 50 or so individual florets.  The stamens are hidden well inside the florets (Fig. b) but dissection (Fig. c) shows that the filaments are ribbon shaped, shorter than the anthers (Fig. d) and partly fused to the inner surface of the perianth.

Each floret produces lots of nectar (there are several droplets clearly visible in Fig. d) and of course a strong scent, both of which attract insects.  Although there aren't many anthers, they each carry a heavy load of pollen, and they are strategically placed in a ring, projecting out towards the centre of the tube, just above the stigma.  This means that any insect which takes the trouble to push its way past them (and lots do) will get a generous dusting to carry along to the next plant.  But it will also have to climb over the stigma which will also get well coated with any pollen the insect is carrying.

In short, the entire floret has evolved to be an efficient mechanism for transferring pollen from anther to insect, and from insect to stigma.  With its short tube and filaments, relatively few, but strategically placed anthers and copious amounts of nectar, its structure makes a marked contrast to the wind pollinated flower of Zygocactus truncatus.


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