The plant is characterised by long-lasting flower heads. Flowers of Mesembryanthemum protect their gametes from night-time dews or frosts but open in sunlight. There is an obvious evolutionary advantage to doing this; where sun, dew, frost, wind or predators are likely to damage exposed reproductive organs, closing may be advantageous during times when flowers are unlikely to attract pollinators.
This post is part of the Nature Footsteps Floral Macros meme.
and also part of the Ruby Tuesday meme.