Flax have been domesticated just once from the wild species "Linum bienne", called pale flax. Several other species in the genus "Linum" are similar in appearance to "L. usitatissimum", cultivated flax, including some that have similar blue flowers, and others with white, yellow, or red flowers. Some of these are perennial plants, unlike "L. usitatissimum", which is an annual plant. Cultivated flax plants grow to tall, with slender stems. The leaves are glaucous green, slender lanceolate, 20–40 mm long, and 3 mm broad. The flowers are pure pale blue, 15–25 mm in diameter, with five petals. The fruit is a round,
The Colours of Animals Protection. Chapter 7 Variable Protective Resemblance in Vertebrata, Etc. Chapter 8 Variable Protective Resemblance In Insects. Chapter 9 Protective Resemblances in Lepidoptera (continued). Chapter 10 Warning Colours. Chapter 11 Warning Colours (continued). Chapter 12 Protective Mimicry. Chapter 13 Protective and Aggressive Mimicry. Chapter 14 The Combination of Many Methods of Defence. Chapter 15 Colours Produced by Courtship. Chapter 16 Other Theories of Sexual Colouring. Chapter 17 Summary And Classification. The co-discoverer of natural selection Alfred Russel Wallace, reviewing Poulton in "Nature", was interested by Poulton's observations on thin films producing iridescence: "In some cases dried insects lose some of their