I’m using a small succulent Echeveria to show the rosette structure of this plant – I can’t get high enough to photograph the taller plants from above, especially since a lot of them are prickly.
Succulents have fleshy leaves and store their water within the leaf itself. This Sempervivum succulent is commonly called ‘Hens and Chicks’ for its habit of making small offshoots of itself to the side.
Aloes are another succulent with a rosette structure. This small Aloe called ‘Sea Urchin’ is showing off its red flowers.
Watercolour sketch of the Partridge Breast (Aloe variegata) seen in Arizona.
Both Yucca and Agave plants belong to the family of Agavaceae, and grow in a ‘rosette’ form. 
The rosette structure from the side on a young Yucca plant.
I was often confused about the differences between a Bromeliad and a Yucca, mostly because they both have the rosette structure and less fleshy leaves than the yucca. But the majority of Bromeliads are not succulents and therefore do not store their water in their leaves but in the centre of the plant.
More of Nancy Merrill’s Photo a Week Challenge: Structure in Nature.
Batz Gallery 
Wonderful post and images. Such interesting information about each plant, too. Thanks for joining the challenge!