Sex and death. Two things that come once in a lifetime. But at least after death you're not nauseous. (W. Allen, 1973)

Picture source: Noah Elhardt; subject - Agave deserti; location - Anza Borrego State Park

Annual and biennial plant species die after they have flowered and set seed - they are monocarpic or semelparous.

Perennials commonly flower over and over (they are polycarpic or iteroparous); but there are some long-lived monocarpic species - certain bamboos, for example.

Amongst the most spectacular of suicidal perennials is Agave, the century plant.  The picture above shows what happens when Agave flowers (despite its name, the plant usually lives for no longer than about thirty years).

Another conspicuous monocarp is the Madagascar pine Tahina spectabilis (pictured on the right).  The press release from Kew Gardens about this newly-described species was picked up by the BBC and even got a spot on the Today Programme, a rare achievement for a plant senescence story.

Is there some kind of fundamental biological connection between big-bang reproductive death in the plant kingdom and semelparity in animals?  This remains one of the unanswered questions of gerontology.

Of course the parallels between plants and animals in the matter of suicidal reproduction need to be drawn with caution. Take bees, for example.

Upon her brief virgin flight, the queen will mate repeatedly with hundreds or thousands of drone bees.

During copulation, the drone bee inserts his endophallus and ejaculates his semen. The endophallus is ripped off during this process and remains inside the queen.

The next drone removes the remains before copulating with the queen and soon experiences the same fate - a quick death after the bursting of his lower abdomen. This is the only role of the drones in the bee colony.

Bees are frequently the agents of pollination; but it's difficult to relate this tale of genital mutilation to the impersonal and (usually) remote relationship of parents in plant reproduction...