Q.Make a list of algae and fungi that have commercial value as source of food, chemicals, medicines and fodder.

Economic botany is simply the study of how plants are useful to people — the foods, fuels, medicines and industrial materials we draw from them. It is an everyday idea: think of how much of your day, from the sugar in your tea to the wood in your furniture, traces back to some plant. In the plant kingdom, almost every group turns out to earn its keep in this way, and listing those uses is a good habit because it makes an abstract group of organisms suddenly concrete and memorable.

Running through the major groups, the practical value shows up again and again:

• Algae are surprisingly important. Through photosynthesis they carry out at least half of all carbon dioxide fixation on Earth and raise the oxygen dissolved in water, and they are prime primary producers feeding aquatic food cycles. Many are eaten directly — about seventy species of marine algae, including kinds of Porphyra, Laminaria and Sargassum, are used as human food. Brown algae yield algin and red algae give carrageen, both water-holding hydrocolloids used commercially. Agar, from Gelidium and Gracilaria, is used to grow microbes in the laboratory and in making ice creams and jellies, while the protein-rich single-celled Chlorella serves as a food supplement, even for space travellers.
• Bryophytes have little direct economic value, yet Sphagnum moss yields peat, long burnt as fuel and, because it holds water so well, used as packing material for shipping living plants. Some mosses are food for animals, and mosses with lichens are pioneer colonisers that break down bare rock and, growing as dense mats, cushion raindrops and check soil erosion.
• Pteridophytes are used medicinally, act as soil-binders that hold the soil together, and are grown as ornamental plants. …