" Me Aussie mate John Catlan says he knows how Neoregelia concentrica and other neoregelias get concentric lines. His idea seems logical but perhaps others can prove him wrong or try to! Remember that Bromeliads are monocotyledons and therefore grow from the base. I quote from the Queensland, Australia, Gold Coast 'Bromlink' Nov/Dec 1998. "" The concentric markings which are a characteristic of this species are intensified under our climatic conditions. These markings are caused by the evaporation of moisture from the miniscus(top of the liquid) of the water in the cup. This evaporation causes a sudden drop in temperature on the leaf surface along the miniscus which destroys the ability of the cells to produce chlorophyll. This allows melanine markings to be displayed on the leaf surface (from the pigment carotenoids within the leaf). The spots on the leaf surface are caused by the evaporation from a drop of water with the result, a spot on the leaf surface. Hot dry weather will give you the best marking especially if the plants are growing in their maximum light conditions.
Sometimes pups come out at an angle where the water in the cup gives the miniscus an oval shape, the concentric rings under these conditions will be oval. Often two leaves will be very close together in the cup. The water pressure between the leaves will cause the miniscus to rise up. Under these conditions the markings will still follow the miniscus.
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