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 come into play". To make the point, Wallace lists "the cones, cowries, olives, harps, volutes, pectens, and innumerable other molluscan shells; while many of the sea-anemones, and considerable numbers of the caterpillars with warning colours, are equally beautiful." And that was not all. Wallace continued: "Still more doubtful and more opposed to reasonable probability is the statement that 'our standards of beauty are largely derived from the contemplation of the numerous examples around us, which... have been created by the æsthetic preferences of the insect world'--alluding... to the colours and structures of flowers as being due to the need of