Linum lewisii Linum lewisii Linum lewisii ("Linum perenne" var. "lewisii") (Lewis flax, blue flax or prairie flax) is a perennial plant in the family Linaceae, native to western North America from Alaska south to Baja California, and from the Pacific Coast east to the Mississippi River (USDA Plant Profile: "Linum lewisii"). It grows on ridges and dry slopes, from sea level in the north up to in the Sierra Nevada. It is a slender herbaceous plant growing to 80 cm tall, with spirally arranged narrow lanceolate leaves 1–2 cm long. The flowers are pale blue or lavender to white, often veined in
The Different Forms of Flowers on Plants of the Same Species reflections indicate the economy of nature through a process of gradual modification of plants, their structures being modified and degraded for the purpose of the large scale production of seed which is necessary and advantageous for survival. Darwin states (p. 227): "Cleistogamic flowers ... are admirably fitted to yield a copious supply of seed at a wonderfully small cost to the plant." Francis Darwin indicated that the work on heterostylism had given his father extreme pleasure, especially as it had been one of the most puzzling bits of work he ever carried out. Darwin thought that hardly anyone had seen