Australian Plants Society Tasmania Inc.

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The Story of Gondwana.

Gondwanan Flora Families.

Proteaceae

The Proteaceae are a family of flowering plants mainly found in the Southern Hemisphere in Australia and South Africa. The family has about 83 genera with nearly 1,700 species. Well known genera include Australia’s Banksia, Dryandra, Grevillea, Hakea and Macadamia, South African Protea and South American Embothrium. Lomatia is common to both Australia and South America. The family name Proteaceae by Antoine L. de Jussieu in 1789 was based on the genus Protea which in 1767 Carl Linnaeus derived from the Greek god Proteus, a deity that was able to change between many forms. This is an appropriate image, seeing as the family is known for its astonishing variety and diversity of flowers and leaves.

The family are generally, rarely of more than 40m in height, and are usually of medium height or low or perennial shrubs, except for Stirlingia species that are herbs. Tasmania has 28 species from 12 genera, Agastachys (1E), Banksia (2), Bellendena (1E), Cenarrhenes (1E), Conospermum (1E), Grevillea (1), Hakea (6 + 2E), Isopogon (1), Lomatia (3E), Orites (4E), Persoonia (1 + 3E) and Telopea (1E); (E indicates endemic species, 18 in total).

Proteaceae flower parts occur in fours, but the four tepals (flower parts) are fused into a long narrow tube with a closed cup at the top and the filaments of the four stamens are fused to the tepals, in such a way that the anthers are enclosed within the cup. The pistil initially passes along the inside of the perianth (floral) tube, so the stigma, too, is enclosed within the cup. As the flower develops, the pistil grows rapidly. Since the stigma is trapped, the style must bend to elongate, and eventually it bends so far, it splits the perianth along one seam. The style continues to grow until anthesis, when the nectaries begin to produce nectar. At this time, the perianth splits into its component tepals, the cup splits apart, and the pistil is released to spring more or less upright. Birds, small marsupials and insects usually assist with pollination. In some cases there are a lot of flowers produced but only a few fruits develop. Fruits consist of cones of multiple follicles as on Banksias, single follicles as on Hakea, cones of many nuts as on Isopogons, clusters of small nuts as on Agastachys or fleshy drupes as on Persoonia plants. Some follicles, Banksias, contain two seeds with a woody divider between them, other follicles, Hakeas, lack the divider and yet other follicles, Lomatias, contain multiple seeds. However Lomatia tasmanica does not set fruit, it is sterile. Most, if not all, follicle seeds are winged (a very thin, light membrane) which aids wind dispersal away from the parent plant.

Many of the Proteaceae have specialised proteoid roots, masses of lateral roots and hairs forming a radial absorptive surface, produced in the leaf litter layer during seasonal growth and usually shrivelling at the end of the growth season. They are an adaption to growth in poor, phosphorous-deficient soils, greatly increasing the plants access to scarce water and nutrients by exuding carboxylates that mobilise previously unavailable phosphorus. They also increase the root’s absorption surface, but this is a minor feature, as it also increases competition for nutrients against its own root clusters. However, this adaptation leaves them highly vulnerable to dieback caused by the Phytophthora cinnamomi water mould and generally intolerant to fertilisation. Due to these specialised proteoid roots, the Proteaceae are one of the few flowering plant families that do not form symbiosis with arbuscular mycorrhizal fungi. They exude large amounts of organic acids (citric and malic acids) every 2-3 days in order to aid the mobilisation and absorption of phosphate. Many species are fire-adapted, meaning they have strategies for surviving fires that sweep through their habitat. Some are resprouters, and have a thick rootstock buried in the ground that shoots up new stems after a fire, and others are re seeders, meaning the adult plants are killed by the fire, but disperse their seeds which are stimulated by the smoke to take root and grow. The heat was previously thought to have stimulated growth, but the chemicals have now been shown to cause it.

(Based on an article on Proteaceae family in Wikipedia and information in Tasmania’s Natural Flora.)

Eucryphiaceae

The family Eucryphiaceae has been split off from a larger family, Cunoniaceae, and has one genus, Eucryphia with seven species, five of which are Australian and two are South American (Chile and Argentina). Tasmania has two species, Eucryphia lucida¸ Leatherwood, a tall, up to 12m, rain forest species which is famous for its strong flavoured honey, and Eucryphia milliganii, Dwarf Leatherwood, a bush or small tree to 3m with smaller leaves and flowers.
It is a montane species. Both Tasmanian species have four rounded petals, usually white on E. lucida but occasionally pink; always white on E. milliganii. The two South American species, Eucryphia cordifolia, Ulmo, and Eucryphia glutinosa, Nirrhe, are both large trees with four petalled, fragrant white flowers. E. cordifolia also produces flavoursome honey and it has been reported that E. lucida has been hybridised with E. cordifolia to produce greater quantities of honey. E. glutinosa is a deciduous tree with its glossy dark green leaves turning red in autumn. It is endemic to Chile, whereas E. cordifolia is found along the Andes Range in Chile and Argentina up to 700m asl. Eucryphia lucida and Eucryphia cordifolia are both threatened by logging and habitat loss.

(References include Tasmania’s natural Flora, Wikipedia and other minor sources)

Fagaceae

The Tasmanian Herbarium classifies the genus Nothofagus in the Fagaceae family and both Tasmanian species, Nothofagus cunninghamii and Nothofagus gunnii are classified accordingly. However, recently some botanists have reclassified all the world’s 43 Nothofagus species of Southern beeches into the family Nothofagaceae with four subgenera: Brassospora including species from New Guinea and New Caledonia, plus a number of now extinct Tasmanian and a New Zealand species;Fuscospora including
Nothofagus alessandri from Chile, Nothofagus gunnii from Tasmania and three species from New Zealand plus another extinct Tasmanian species; Lophozonia including Nothofagus alpina, N. glauca, N. macrocarpa and N. obliqua from Chile and Argentina, Nothofagus cunninghamii from Tasmania and Victoria, Nothofagus moorei from NSW and Qld, and Nothofagus mensiesii from New Zealand, plus more extinct Australian and NZ species; and, subgenera Nothofagus including the remaining species from Argentina and Chile, plus two more extinct Tasmanian species. One more extinct species either 3 or 15 million years old has been identified from Antarctica. This reclassification has not been accepted outside New Zealand. While Nothofagus cunninghamii is a large, evergreen tree with bronze/red new leaves, up to 40 – 50m high in rainforest, N. gunnii is a deciduous, woody, montane shrub or small tree, 0.2 -4m high. In Autumn, many Tasmania’s do a pilgrimage to the montane areas of the state to see the N. gunnii foliage changing colour from brilliant green to yellows, oranges and sometime bright red. N. gunnii is Tasmania’s only deciduous tree. The wood of N. cunninghamii, like many Nothofagus species wood makes beautiful timber and many pieces of furniture feature solid or veneer parts. Another Gondwanan feature of the Nothofagus species is the Cyttaria fungus that grow on the branches of some Nothofagus trees. Cyttaria darwinii grows on N. antarctica and N. pumilio, and occasionally on N. betuloides and N. dombeyi in Argentina, South America. Cyttaria gunnii, Myrtle orange, grows only on N. cunninghamii in Tasmania and Victoria, and Cyttaria septentrionalis grows on N. moorei in NSW and Qld. Cyttaria purdiei grows only on N. menziesii in New Zealand.

(References include the Nothofagus and Cyttaria articles in Wikipedia, Tasmania’s Natural Flora, and other minor sources)

Myrtaceae

The family Myrtaceae are the largest of the Gondwana families with about 132 genera and nearly 6,000 species. Recent classification of the family recognises two subfamily, Psiloxyloideae with 2 tribes, Psiloxyleae and Herteropyxideae, and subfamily Myrtoideae with 15 tribes including Australia’s Melaleucaeae, Backhousieae, Tristanieae, Syzygieae, Eucalypteae, Leptospermeae and Chamelaucieae. South America has Myrteae and Metrosidereae.

Some of the most famous Australian genera are Agonis, Angophora, Calytrix, Chamelaucium, Darwinia, Eucalyptus, Kunzea, Leptospermum, Melaleuca, Syzygium, Thryptomene, Tristania, and Verticordia.

Some of the South American genera are Accara, Blepharocalyx, Calcolpus, Calycorectes, Calyptranthes, Campanesia, Eugenia, Gomidesia, Hexachlamys, Marlierea,Mosiera, Myrceugenia, Myrcia, Myrciaria, Neomitranthes, Plinia, Siphoneugena, Ugni, and the most well known in Tasmania, Amomyrtus and Metrosideros.

Myrtaceae flowers usually have five sepals and petals and many stamens which are long and conspicuous. Some species like Leptospermum have single flowers, some like Eucalyptus have small clusters of flowers, and others like many Melaleuca have cylindrical spikes of multiple flowers. In Eucalypts, the petals and sepals are joined to form a cap over the bud Eucalyptus species are now grown worldwide for timber, making charcoal, pulp wood for paper and essential oils. Due to the lack of predatory animals and insects they grow more quickly in many overseas places than in Australia. Eucalypts vary in size from shrubs to large and in the right conditions very tall trees. Eucalyptus regnans, Giant Ash, which grows to over 100m h, is considered to be the tallest flowering plant in the world. In Tasmania, Eucalypts grow from the coast to montane areas of the state. In some of the southern and western montane areas, a rare species, Eucalyptus vernicosa, Varnished gum, grows to only 2.0m h. Leptospermum are also grown widely for essential oil and honey production.

(Information gleaned from Tasmania’s Natural Flora, Plant Families – Australian National Botanical Gardens – Education and other minor sources.)

Winteraceae

The Winteraceae family has over 60 species in five or more genera that grow mainly in the southern hemisphere from tropical to temperate climate regions. Australia has ten species in two genera, Bubbia, with two species from Queensland, and Tasmannia, with eight species, only one of which grows in Tasmania. Tasmannia lanceolata, Mountain pepper, grows from coast to subalpine areas in Tasmania and similar areas in Victoria and New South Wales, usually in wet sclerophyll habitats. It has become an important culinary species with its leaves and especially its fruit being used as a pepper substitute. Tasmannia lanceolata is notable for its glossy, dark green leaves on red stems and terminal clusters of yellow male and female flowers in spring to summer on separate plants. The berry fruit mature from green to red then black when ripe.

The most notable species in South America is Drimys winteri, Winter’s bark, which grows in the temperate rain forests of Chile and Argentina. Its fragrant, red bark is very attractive and has been used historically to prevent scurvy. It has jasmine-scented, creamy white clusters of flowers.

Other Winteraceae species are found in Malesia, Oceania, New Zealand and Madagascar. Pollen samples from the family, which is quite distinctive, has been found in fossils estimated to be 120 million years old. They also indicate that the family disappeared from Africa about 24 million years ago.

(References include Flora of Australia volume 2, Tasmania’s Natural Flora and Wikipedia)