Classification and naming of plants - Principles of Horticulture - page 61

X Ground cover : low growing, usually evergreen
plants designed to completely cover the soil, e.g.
Hedera (ivy), Vinca (periwinkle), Epimedium .

Fungi

The kingdom Fungi is a very diverse group about which
much remains to be studied. It has been estimated
that there are 1.5 to 5 million species of which only
5% has been classified to date! Some fungi are single
celled (such as yeasts), but others are multicellular,
such as the moulds and the more familiar mushrooms
and toadstools (Figure 4.13). Most are made up of a
mycelium, which is a mass of thread-like filaments
(hyphae) which generally remains hidden from view.
The mushrooms we see at certain times of year are
the spore-producing part of the life cycle. Fungal cell
walls are made of chitin not cellulose as in plants.
Fungi obtain their food directly from other living
organisms (heterotrophic nutrition), sometimes
causing disease (see Chapter 19), or from dead
organic matter, so contributing to its beneficial
breakdown in the soil (see Chapters 3 and 13). They
achieve this by secreting digestive enzymes onto their
food source and absorbing the soluble products.
In horticulture, fungi (mushrooms) are also important
as a food crop. Mycorrhiza and lichens are examples
of a mutualistic relationship between fungi and other
organisms (Figure 4.14).
See 'Non-Plant Kingdoms' on the companion website.

(a)

4

(b)

(c)

Figure 4.14 Lichens - a combination of a fungus and
a cyanobacterium: (a) Xanthoria spp.; (b) Parmelia spp.;
(c) Usnea spp.

Figure 4.13 Shaggy ink cap, a fungus showing its
fruiting bodies