Q.What Is Growing On Thse Leaves. It Is From A Eucalyptus Tree And Has Infested Almost All Trees In Garden And Street.
Leaves are falling off trees in our garden and along most of the street. They have a hard seed like pods forming on leaf surfaces and eventually drop from branches. Location is in Eltham , Melbourne Australia.

Certified GKH Gardening Expert
This is likely a type of Gall wasp. You can control them with some maintenance. Here are some articles that will help:
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/azadirachtin-vs-neem-oil.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/homemade-soap-spray.htm