Southwest Australian Vegetation
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Plant Formations in the Southwest Australian BioProvince Peter Martin Rhind Southwest Australian Jarrah Forest Unlike most of the World’s hardwood forests this type of forest is almost exclusively dominated by a single species the Jarrah (Eucalyptus marginata), which can form almost pure stands in certain areas especially where laterite soils predominate. The only other commonly associated trees are Eucalyptus calophylla (marri), E. patens (blacknut) and E. wandoo (wandoo). Commonly associated under storey species include the strange Casuarine fraserana and various banksias (Proteaceae) such as Banksia grandis, B. menziesii and B. attenuata. However, in addition there are various arborescent monocots such as the endemic Dasypogon hookeri, Kingia australis and Xanthorrhoea gracilis (Xanthorrhoeaceae). The most common liana is the endemic Kennedia coccinea (Fabaceae) and, in fact, both lianas and creepers are common features of these forests. The shrub layer, unlike the canopy, is also rich in species with many endemics. The most common of these is Stirlingia latifolia (Proteaceae), while other species include Acacia alata, Adenanthos barbigerus, Conospermum glumaceum, Dryandra praemorsa, Grevillea willsoni, Hakea lissocarpha, Isopogon sphaerocephalus (Proteaceae), Andersonia axilliflora, Astroloma ciliatum (Epacridaceae), Anigozanthos preissii (Haemodoraceae), Chorizema dicksonii, Daviesia cordata, Gastrolobium villosum (Fabaceae), Darwinia carnea, Hypocalymma robustum (Myrtaceae), Hemiandra linearis (Lamiaceae), Hibbertia hypericoides (Dilleniaceae), Lechenaultia biloba, Scaevola platyphylla (Goodenaceae), and Primelea rosea (Thymeleaceae). The ground layer is also richly endowed with endemics including various orchids such as Caladenia gemmata, Caladenia macrostylis, Caladenia sericea, Prasophyllum fimbria, Pterostylis barbata, Pterostylis recurva and Thelymitra crinita (Orchidaceae), while other ground dwelling, largely perennial herbs include Anigozanthos bicolor, Conostylis androstemma, Conostylis setigera (Haemodoraceae), Dampiera linearis (Goodeniaceae), the insectivorous Drosera microphylla and D. platystigma (Droseraceae), the ground hugging Dryandra nivea (Proteaceae), Goodenia fasciculate, Scaevola striata (Goodeniaceae), Kennedia stirlingii (Fabaceae), Orthrosanthus laxus, Patersonia xanthina (Iridaceae), Ptilotus manglesii (Amaranthaceae), Tetratheca viminea (Tremandraceae) and Trichocline spathulata (Asteraceae). A slightly sinister aspect of these forests is the many toxic species. These are particularly prevalent in the endemic genus Gastrolobium such as Gastrolobium calycinum (york road poison). Other highly toxic species include the endemic Isotoma hypocrateriformis (woodbridge poison) of the Lobelliaceae, various species of Oxylobium and the endemic cycad Macrozamia riedlei (Zamiaceae). These forests also provide habitat for the strange parasitic plant Pilostyles hamiltonii - Australia’s only representative of the family Rafflesiaceae. A better-known example is Rafflesia arnoldii, which has the World’s largest flower. In contrast Pilostyles has comparatively small flowers, just a few millimeters across, but like its larger relatives, spends most of its life cycle in the tissues of various host plants, which locally include various members of the genus Daviesia. Southwest Australian Karri Forest On the loams and sandy loams over granitic and gneissic rocks the forests are mainly dominated by the endemic Eucalyptus diversicolor (karri), which is credited with being one of the three tallest hardwoods in the World measuring up to 90 m. In fact, it dwarfs most of the associated tree, although one of these, Eucalyptus jacksonii, can reach heights of 70 m. Other trees include Agonis juniperina and Eucalypus guilfoylei, while smaller trees Copyright © 2010 Peter Martin Rhind growing far below the karri canopy include the endemic Agonis flexuosa (Myrtaceae). Altogether there may be three or four stories to these forests. A dense shrub layer is always present and commonly includes Trymalium spathulatum and the endemic Chorilaena quercifolia (Rutaceae). Other endemic shrubs include Acacia pentodenia (Fabaceae), Chorilaena quercifolia (Rutaceae), Hibbertia cuneiformis (Dilleniaceae), Leucopogon verticillatus (Fabaceae), and a number of very attractive species such as Boronia gracilipes, Crowea angustifolia (Rutaceae), Chorizema ilicifolium and Hovea elliptica (Fabaceae). Few members of the southern heath family Epacridaceae occur in these forests, but the endemic Leucopogon verticillatus may be found. Underneath the shrubs large quantities of litter, bark and leaves accumulate. Despite this a number of herbaceous plants occur including various endemic species such as Dampiera hederacea (Goodeniaceae), and at least five species of fern. Of these Pteridium esculentum (a native bracken) is the most common, and is the largest native species growing to heights of 2 m, while other include Adiantum aethiopicum and Lindsaea linearis. Southwest Australian Coastal Limestone Communities In the more exposed situations where salt spray is driven inland by winter storms, just a few small shrubs of Frankenia pauciflora mainly colonize this coastal limestone. Further inland this gives way to a heathland community of Dryandra, Hakea and Melaleuca, while in the more sheltered valleys trees such as Callitris preissii, Eucalyptus gomphocephala, Melaleuca lanceolata may occur. Endemic species found here include shrubs such as Diplolaena angustifolia (Rutaceae), Dryandra sessilis (Proteaceae), Melaleuca heugelii (Myrtaceae), and the creeper Kennedia coccinea (Fabaceae). Southwest Australian Coastal Sand Dune Communities In the mobile dunes exposed to salt-laden winds, the main species include various dune grasses such as Spinifex longifolius and S. hirsutus, together with a variety of cosmopolitan species like Cakile maritima. In the more stable zones further inland a form of low heath occurs composed of species such as Acanthocarpus preissii, and the endemic Acacia pullchella (Fabaceae), Calectasia cyanea (Xanthorrhoeaceae) and Hibbertia hypericoides (Dilleniaceae). Other endemics associated with dunes include the shrubs Diplolaena dampieri (Rutaceae) and Rhagodia radiata (Chenopodiaceae). Banksias (Proteaceae) are also a feature of the coastal dunes in the south, particularly between Hopetoun and Israelite Bay. Here showy species such as Banksia speciosa, B. nutans and the endemic B. baxteri and B coccinea occur. Deeper coastal sand provides habitat for members of the endemic genera Anigozanthos and Conostylis including Anigozanthos rufus and the attractive Conostylis bealiana, C. petrophiloides and C. vaginata. Southwest Australian Bush of Southern Sand Plains This region includes the undulating plains along the south coast from Pallinup River to Israelite Bay and extends inland to Lake Grace. Two of the more prominent shrubs of these southern bush lands are Hakea crassifolia and the endemic Lambertia inervis (Proteaceae). The latter represents a near endemic genus with all but one species endemic to the southwest. Another widespread endemic shrub found here is the unusual Franklandia fucifolia (Proteaceae), while other important shrubby species are the so-called bottlebrushes Beaufortia micrantha, B. orbifolia and B. schaueri, and the wax flowers Chamelaucium axillare and C. megalopetalum (Mrytaceae). Both genera are endemic to the southwest, with some 15 species of Chamelaucium. Among the endemic herbs are species of the endemic genus Anthotium (Goodeniaceae) including Anthotium humile and A. rubiflorum. Both have perennial rootstocks and rosetted linear leaves. Copyright © 2010 Peter Martin Rhind Southwest Australian Bush of Northern Sand Plains These sandy plains occur north of Perth between Moore River and Shark Bay. Like their southern counterpart two of the most prominent families are Proteaceae and Myrtaceae. In the former there are at least 20 species of Banksia including the endemic B. burdettii and many species of the endemic Dryandra such as D. nana, D. carlinoides, D. kippistiana, D. shuttleworthiana and D. speciosa. Most dryandras and banksias produce abundant nectar and although birds and insects are attracted to this, it seems that small marsupials are the main pollinators. Other conspicuous members of the Proteaceae include the grevilleas, such as the spectacular white plume grevellea (Grevillea leucopteris) and the endemic smokebush Conospermum stoechadis. Of the Myrtaceae, the intriguing genus Darwinia, with its great diversity of inflorescences, is well represented with some 30 species endemic to the southwest. Two of the more common of these are Darwinia neildiana and D. speciosa. Other indigenous members of this family include various species of the genus Calothamnus. All 25 species of this genus are endemic to the southwest but only about 10 occur on the northern sand plains including Calothamnus blepharospermus, C. homalophyllus and C. quadrifidus. Also present are many poisonous plants of the endemic genus Gastrolobium, such as Gastrolobium oxylobioides, which have caused problems for pastoralists since the early days of settlement. Flowers of many colours are seen in the family Goodeniaceae and even in the genus Lechenaultia with about 25 species, flowers may be blue, white, yellow, red, orange or green. One of the more common of these is the endemic blue lechenaultia (Lechenaultia biloba). In areas of deep sand are various members of the enigmatic, endemic genus Anigozanthos, including Anigozanthos manglesii