11. Each areole has up to 26 radial spines which are red, pink, or white in color. 12. Each areole has some wool and several slightly curved yellowish to white spines up to half a centimeter long. 13. There are many spines on each areole , the central ones up to 4.4 centimeters in length. 14. There are up to 21 bristle-like radial spines on each areole and one to three hooked central spines. 15. A typical areole may have one or a few long, sharp central spines, which serve as the primary defense. 16. Beneath them are often numerous ( 10 or more ) smaller, radial spines produced around the edge of the areole . 17. The outer perianth segments are linear, green, and tipped by an areole like those of the tube and ovary. 18. The development of the areole seems to have been an important element in the adaptation of cacti to niches in desert ecology. 19. Each areole commonly has 1-7 roundish to angular apothecia that are . 1-1.3 mm in diameter. 20. There is a single straight central spine to each areole , long, and five to seven more slender radial spines, long.
