Strigolactones are known to stimulate the germination of arbuscular mycorrhiza spores. Therefore, germination can take place only by means of infection with a root fungus (mycorrhiza). Plants can increase phosphorus uptake by a mutualism with mycorrhiza. Other important soil organisms include nematodes, mycorrhiza and bacteria. Fungi feed on plants but can also provide essential nutriment to saplings (Mycorrhiza). The biology of mycorrhiza in the Ericaceae. These fungi form a mycorrhiza with nearby tree species. This type of mycorrhiza involves plants of the Ericaceae subfamily Arbutoideae. The roots of "Epacris impressa" are colonized by fungi forming ericoid mycorrhiza. For example, "T. inflatum" had a small but significant effect on inhibiting mycorrhiza formation. Due to this orchid mycorrhiza in general are considered at least partially mycoheterotrophic interactions. It is associated with arbuscular mycorrhiza that penetrate the cortical cells of the roots. The grass tree has a symbiosis relationship with Mycorrhiza deep in its root system. Symbiotic relationships between fungi and plant roots is referred to as a Mycorrhiza association. A mycorrhiza is a symbiotic association between a green plant and a fungus.