Digitalis from purple to pink, white, and yellow. The best-known species is the common foxglove, "Digitalis purpurea". This biennial plant is often grown as an ornamental plant due to its vivid flowers which range in colour from various purple tints through pink, light grey, and purely white. The flowers can also possess various marks and spottings. The first year of growth produces only the stem with its long, basal leaves. During the second year of the plant's life, a long, leafy stem from 50 to 255 centimetres tall grows atop the roots of healthy plants. Other garden-worthy species include "D. ferruginea",
Plant physiology plants produce a vast array of chemical compounds with unique properties which they use to cope with their environment. Pigments are used by plants to absorb or detect light, and are extracted by humans for use in dyes. Other plant products may be used for the manufacture of commercially important rubber or biofuel. Perhaps the most celebrated compounds from plants are those with pharmacological activity, such as salicylic acid from which aspirin is made, morphine, and digoxin. Drug companies spend billions of dollars each year researching plant compounds for potential medicinal benefits. Plants require some nutrients, such as carbon and