Some plants are good to have around pets, others can harm your pets, but most are neither especially beneficial or harmless. It is important to know at least the harmful one and avoid them. Some pets can develop allergies also, in the same way that some people can.
PLANTS THAT MAY CONTROL MOVEMENT OF DOGS and CATS
Coleus caninus/canosus -scent tends to repel a relatively large proportion of dogs & cats.
Dense prickly hedges can be created using to deter movement of animals, using plants such as Lycium ferocissimum, Acacia tortilis, Oncoba spinosa, Chenomeles sp., Carissa sp.
Larger thorny plants (eg. Cretagus, Bougainvillea) can work for large animals like cattle, but will be unlikely to contain small dogs or cats.
PLANTS THAT MAY HARM DOGS
These include dense low bushy plants -attract rodents, bandicoots (in bush areas) etc which can carry ticks.
Wandering Jew (Tradescantia) is reported to be harmful to dogs.
PLANTS THAT HARM CATS
Avoid too many tall shade trees. Cats need sunny places to sun bathe. Toxic plants (see below) can be a problem; but catnip is a herb that will actually attract cats.
PLANTS THAT MAY NOT BE DESIRABLE IF YOU HAVE DOGS OR CATS
These may cause a rash if the plant contacts the animals skin:
Solanum species (eg tomato, potato, tobacco)
Plants that attract bees can result in your animals receiving stings (Clover flowers in an unmown lawn is a particular problem).
Plants that attract birds and small mammals (eg. Grevilleas & Callistemons) may make cats happy, but can result in native animals falling prey to cats.
The following plants that contain oxalic acid can cause mouth inflammation or staggering in extreme cases:
Plants that may occasionally be eaten, thereby causing varied, but sometimes serious affects include:
all lily related plants (eg Asparagus fern, Amaryllis, Daffodil)
Azalea and Rhododendron
Castor Oil Bean
Mock Orange (Choisya ternata).
Any plant that may have been sprayed with a chemical to control pests or diseases could be considered as harmful to your cat or dog. It is therefore best to select plants that do not need spraying.