A family of cactus grow in my grand-mother’s front garden. She told me Pepere planted them, so they must be at least 15 years old, but they don’t look it. The tallest no higher than half a foot. From some angles, they look like marching people. Small, purplish baby cacti shoot off from the tops. Looking closer, neat rows of prickles parade up and down. What a mathematical plant. And Memere says they bloom beautifully for one day only of the year.