The Southern Volcanic Plain was created by volcanic activity that began 4.5 million years ago and continued until 10 000 years ago. On average, an eruption took place every 10 000 years and over 400 eruption points have been identified. Although there were some explosive eruptions that produced circular craters (maars), which now contain lakes and swamps, most were small volcanoes, active for a few years or decades. These deposited thin broad shields or long lava flows of basalt 2–10 m deep, creating broad plains, but other flows up to 100 m thick filled existing valleys. Native grasslands occur in areas where these flows have experienced long periods of weathering, producing heavy grey, red or black cracking clay soils, which are generally fertile but poorly drained. In contrast, the youngest relatively unweathered lava flows are known as stony rises and have thin soils and support woodland vegetation dominated by genera such as Banksia (Banksias), Acacia (Wattles) and Allocasuarina (She-oaks and Bull-oaks).
The dominant native grass of the Victorian Volcanic Plain grasslands is Themeda triandra (Kangaroo Grass) which is a summer growing tussock forming species. A range of winter growing grasses – including Rytidosperma spp. (Wallaby Grasses), Dichelachne spp. (Plume Grasses) and Austrostipa spp. (Spear Grasses) – occur as minor components in most grasslands, but increase in abundance where soils are shallow (soil moisture stress reduces Kangaroo Grass productivity) and where past heavy stock grazing has occurred. Poa labillardierei (Common Tussock-grass) occurs in wetter areas, such as drainage lines. A variety of perennial forbs occupy the spaces between grass tussocks. Intertussock species that occur throughout the range of the community include Eryngium ovinum (Blue Devil), Acaena echinata (Sheep’s Burr), Leptorhynchos squamatus (Scaly Buttons), Convolvulus angustissimus (Pink Bindweed) and Schoenus apogon (Common Bog-rush). In areas of higher rainfall to the west of the bioregion, other species that frequently occur include Microtis unifolia (Common Onion-orchid) and Drosera peltata (Pale Sundew). In lower rainfall areas, Chrysocephalum apiculatum (Common Everlasting) and Calocephalus citreus (Lemon Beauty-heads) become more prevalent.
Acaena echinata, Asperula scoparia, Atriplex semibaccata, Rytidosperma caespitosum, Rytidosperma duttonianum, Austrostipa bigeniculata, Austrostipa nodosa, Austrostipa scabra, Brachyscome basaltica, Calocephalus citreus, Calocephalus lacteus, Carex tereticaulis, Centrolepis aristata, Centrolepis strigosa, Euphorbia drummondii, Chrysocephalum apiculatum, Convolvulus angustissimus, Craspedia variabilis, Crassula helmsii, Dichelachne crinita, Dichondra repens, Distichlis distichophylla, Drosera peltata, Drosera whittakeri subsp. aberrans, Eleocharis acuta, Elymus scaber, Eryngium ovinum, Gonocarpus tetragynus, Goodenia pinnatifida, Haloragis heterophylla, Hemarthria uncinata, Hydrocotyle sibthorpioides, Juncus kraussii subsp. australiensis, Juncus planifolius, Lachnagrostis filiformis, Leptorhynchos squamatus, Lobelia pratioides, Maireana enchylaenoides, Microlaena stipoides, Microseris sp., Microtis unifolia, Oxalis perennans, Pimelea curviflora, Pimelea humilis, Plantago gaudichaudii, Poa labillardierei, Ptilotus macrocephalus, Rumex dumosus, Schoenus apogon, Senecio quadridentatus, Senecio tenuiflorus, Solenogyne dominii, Thelymitra pauciflora, Themeda triandra, Walwhalleya proluta
Eastern Grey Kangaroo, Fat-tailed Dunnart, Common Dunnart, Eastern Barred Bandicoot, White-striped Mastiff-bat, Striped Legless-lizard, Glossy Grass Skink, Southern Grass Skink, Bougainville's Skink, Cunningham's Skink, Tussock Skink, Common Blue-tongue Lizard, Tiger Snake, Eastern Brown Snake, Little Whip Snake, Marbled Gecko, Growling Grass Frog, Bibron’s Toadlet, Common Eastern Froglet, Eastern Sign-bearing Froglet, Southern Bullfrog, Southern Toadlet, Spotted Marsh Frog, Striped Marsh Frog, Peron's Tree Frog, Southern Brown Tree Frog, Eastern Banjo Frog, Stubble Quail, Red-chested Button-quail, Willie wagtail, Welcome Swallow, Australian Kestrel, Galah, Flame Robin, Black-shouldered Kite, Brown Falcon, Richards Pipit, Little Raven, Masked Lapwing, Magpie Lark, White-fronted Chat, Yellow-rumped Thornbill, Brown Songlark, Rufous Songlark, Golden-headed Cisticola, White-plumed Honeyeater, Brolga, Plains wanderer, Australian Bustard, White-faced Heron, Australian White Ibis, Straw-necked Ibis, Little Eagle, Sulphur-crested Cockatoo, Australian Magpie, Australasian Pipit, Horsfield's Bushlark, Common Greenfinch, Eurasian Skylark, House Sparrow, European Goldfinch, Common Starling, Common Myna, Crested Pigeon, Eastern Rosella, Grey Teal, Red-rumped Parrot, Long-billed Corella, Bush Stone-curlew, Wedge-tailed Eagle, Golden Sun Moth