What continent are the genuses Allocasuarina and Acacia mainly native to? 
mainly native to Australia
Title: Allocasuarina rupicola
Passage: Allocasuarina rupicola, commonly known as shrubby she-oak, is a species of the "Allocasuarina" genus native to Australia.
Title: Acacia
Passage: Acacia, commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae.  Initially it comprised a group of plant species native to Africa and Australia, with the first species "A. nilotica" described by Linnaeus.  Controversy erupted in the early 2000s when it became evident that the genus as it stood was not monophyletic, and that several divergent lineages needed to be placed in separate genera.  It turned out that one lineage comprising over 900 species mainly native to Australia was not closely related to the mainly African lineage that contained "A. nilotica"—the first and type species.  This meant that the Australian lineage (by far the most prolific in number of species) would need to be renamed.  Botanist Les Pedley named this group Racosperma, which was inconsistently adopted.  Australian botanists proposed that this would be more disruptive than setting a different type species ("A. penninervis") and allowing this large number of species to remain "Acacia", resulting in the two African lineages being renamed "Vachellia" and "Senegalia", and the two New World lineages renamed "Acaciella" and "Mariosousa".  This was officially adopted, but many botanists from Africa and elsewhere disagreed that this was necessary.
Title: Allocasuarina robusta
Passage: Allocasuarina robusta is a species of the "Allocasuarina" genus native to Australia.
Title: Allocasuarina rigida
Passage: Allocasuarina rigida is a species of the "Allocasuarina" genus native to Australia.
Title: Allocasuarina
Passage: Allocasuarina is a genus of trees in the flowering plant family Casuarinaceae.  They are endemic to Australia, occurring primarily in the south.  Like the closely related genus "Casuarina", they are commonly called sheoaks or she-oaks.
Title: Acacia deanei
Passage: Acacia deanei (Deane's wattle, green wattle; syn.  "Acacia paucijuga" Wakef.  [= "Acacia deanei" subsp.  "paucijuga"], "Racosperma deanei" (R.T.Baker) Pedley) is a tree native to Australia, which is used for controlling erosion on.  There are two subspecies: "Acacia deanei" subsp.  "deanei" and "Acacia deanei" subsp.  "paucijuga".
Title: Acacia confusa
Passage: Acacia confusa is a perennial tree native to South-East Asia.  Some common names for it are acacia petit feuille, small Philippine acacia, Formosa acacia (Taiwan acacia) and Formosan koa.  It grows to a height of 15m.  The tree has become very common in many tropical Pacific areas, including Hawaii, where the species is considered invasive.
Title: Acacia hispidula
Passage: Acacia hispidula, known colloquially as little harsh acacia, rough-leaved acacia or rough hairy wattle, is a species of "Acacia" native to eastern Australia.
Title: Allocasuarina monilifera
Passage: Allocasuarina monilifera, commonly known as necklace sheoak, is a shrub of the genus "Allocasuarina" native to Tasmania and Australia.
Title: Allocasuarina pusilla
Passage: Allocasuarina pusilla, commonly known as the heath oak-bush or the dwarf she-oak, is a species of "Allocasuarina" genera native to Australia.
Acacia Allocasuarina