RBGE is the only botanic garden in the world that specialises in cryptogams (non-flowering plants). These plants include bryophytes (mosses, liverworts and hornworts), lichens, fungi, algae, and ferns and fern allies. Though cryptogams are often overlooked because they are less conspicuous than flowering plants, they are vitally important in many different ecosystems.
The Garden's outstanding bryophyte herbarium dates back to collections made in the 1790s by the Scottish ship's surgeon and explorer Archibald Menzies. Native bryophytes grow naturally throughout the four gardens, and there are several exotic species in the Glasshouses that probably came in with tender plants.
Lichens are part-fungus and part-alga. Most are long-lived and slow-growing, forming crusts or tufts on bare surfaces which may persist for centuries, yet increase by only a few millimetres a year. Many of Britain's 1700 species occur only in ancient woodlands. They are extremely sensitive to pollution, so they indicate air and water quality. They can be used to assess the conservation value of sites and to date ancient stonework.
Strictly speaking, fungi are neither plants nor animals. They include edible mushrooms, yeasts that allow us to make bread and alcoholic drinks, and harmful plant parasites such as rust fungi. Some form mycorrhizas - largely invisible strands - that sustain the life of woodlands by supplying nutrients to tree roots; others - saprotrophs - rot down dead material and recycle the simpler compounds. Mycologists at RBGE research many aspects of this large and complex group.
Algae are mainly aquatic plants such as seaweed and spirogyra (pond slime). They are enormously important: marine algae perform 50% of all photosynthesis, thereby influencing global climate and fish stocks. Research at RBGE concentrates on green algae and diatoms.
Ferns and fern allies
Ferns, horsetails and clubmosses dominated the Earth's vegetation for 200 million years before flowering plants developed. There are 15 000 species worldwide, of which RBGE has over 6000 herbarium specimens and 300 species in cultivation - including the world's largest collection of horsetails.
Many cryptogams have to be grown with the kinds of plants and conditions with which
they are naturally associated.
The Cryptogamic Garden at Edinburgh is the first of its kind to be constructed in a botanic garden. It was established in the early 1990s, at the western end of the Demonstration Garden, using young trees and clumps of woodland plants lifted, with the owners' permission, from local woodland habitats.
In this way the tree roots were well-supplied with naturally occurring mycorhizas - fungal threads which live in and around the roots. These aid the tree's uptake of scarce minerals, and in return they take in nutrients as well as sugars, which the tree makes through photosynthesis. This exchange is vital to the health of both the tree and the fungus.
Dawyck's Heron Wood Reserve and Cryptogamic Sanctuary was launched six years ago. This is an area of semi-natural woodland with beech, birch, pine and oak, as well as more open glades. The Sanctuary is left untouched, while the Reserve will have some essential maintenance work carried out on it from time to time. Cryptogams thrive in the resulting range of habitats, and these are monitored frequently. So far over 600 different non-lichenised fungi have been recorded, and many more are expected to be found there in years to come.
Benmore Botanic Garden has perfect growing conditions for many cryptogams. The humid atmosphere and the deep layer of litter on the woodland floor suit ferns and fungi, and lichens thrive on the surfaces of trees and rocks.
Logan boasts more than 130 lichens on rocks and bark as a result of its pure air quality. In addition, fungi also thrive here, including two species of subterranean stomach fungi (Gasteromycetes) including the Australian Hymenangium album in association with species of Eucalyptus. Large numbers of ferns and mosses have also colonised the garden, including the maidenhair spleenwort (Asplenium trichomanes).