Hi all -- Wanting to chime in on this topic...We get this question a lot. Most landscape plants are toxic to other living beings. But for the most part your children and pets will not be affected by them if a) you teach them not to eat seed pods and berries and b) the seed pods and berries are too high, beyond their reach. Eve's Necklace, for example, is a beautiful native tree (about the size of a Crape Myrtle but NATIVE to North Central Texas.) It earned its name in part because of the blackish seed pods that dangle off its limbs. The seed pods are toxic to humans if they are ingested. However, they are too difficult for children or pets to reach, and most adults I know aren't inclined to gnaw on their landscape plants.
Also, check the definition of 'toxicity' for each plant. It's a blanket term that encompasses every malady from skin rash, to upset stomach, etc. In other words, toxic doesn't always mean 'death.'
All this said, perhaps one of the deadliest plants for humans in the landscape industry is Oleander. They are colorful, drought-hardy and relatively maintenance free. They are EVERYWHERE. Many people line the perimeter of their pool with them and in Corpus Christi oleanders fill median areas. People constantly come in contact with this plant, but few are ever affected by it. If you trim it, just remember not to burn the limbs. Or use them for barbecue skewers! You would be affected by the toxins in either case...
Some people have allergic reactions to common landscape plants and should avoid planting them. Lantana causes skin rash for some folks, and although it's a terrific plant, they should veer away from using it in their landscape. You or I, fine. But anyone who discovers a reaction to Lantana should probably find a suitable replacement.
One final thought. Think you're allergic to Goldenrod (Solidago spp.)? Well, this is a common misunderstanding. Actually you are most likely allergic to Ragweed which blooms around the same time as Goldenrod and is often found growing alongside it. Goldenrod doesn't release allergens, and is truly an underused landscape plant. There are multiple species native all over the country, so find one that is native to your area and go with it. Great late summer, fall bloomer. Next time you sneeze, blame the Ragweed not the Goldenrod.