# Mathematical Digest

### Short Summaries of Articles about Mathematics

in the Popular Press

"Fibonacci's flowers," by Amar J.S. Klar, *Nature,* 6 June 2002.

How does the pattern of leaf, petal, sepal, and spiral growth in plants conform to the numbers in Fibonacci's famous sequence (in which each number is the sum of the previous two)? The author examines "phyllotaxis"---the phenomenon of right and left spiral formations on sunflower heads and pine cones, for instance---and suggests that asymmetric cell division offers a possible explanation. Klar proposes that researchers look at the stem-cell model and mutants with altered development patterns to examine how asymmetric patterns of cell division may generate Fibonacci patterns in plants.

*--- Annette Emerson*