Floral Splendour and Shortage of Nutrients - Soil: Reflections on the Basis of our Existence - page 43

Phosphorus provider. When Carex and other sedges can grow amazingly intricate root hairs
when exposed to phosphorus deficiency. These produce organic acids that lower the soil pH to
release the elusive phosphorus. The root hairs only grow in extremely phosphorus-poor soils and
are absent in nutrient-rich farmland. But if we could breed sedge varieties to grow root hairs even
in nutrient-rich conditions, we could perhaps access the phosphorus that lies trapped in farmland
from decades of fertiliser use, thereby tapping a valuable resource at a time when global phos-
phorus reserves are running low
meadow flowers germinate and bloom. This is because many flowers have thick
roots that need mycorrhizal fungi to absorb phosphorus. If the fungi are absent,
the flowers are outcompeted by grasses, which have more delicate root systems
better able to absorb phosphorus unaided.
Mycorrhizal fungi are not alone in affecting plant life. Other fungi can infect
plant roots and even kill the host. Rare plant species are often especially sensitive
to such fungi, their very rarity being the result of having to colonise new areas to
mitigate against fungal attacks. Commoner species have generally evolved more
effective defence mechanisms. Some rarer species manage to retain a foothold by