Re: What Plant is this, please? Looks like it could be a milkweed and pod, infected as Ron says. You'll see other pods in more of a teardrop shape, or splitting open and spreading their silky parasol seeds.
Re: What Plant is this, please? Vegetative parts generally like those of ash or walnut, structure of terminal buds doubtless indicative.
Re: What Plant is this, please? Pistacia terebinthus. The second pic shows a gall, caused by the gall aphid Baizongia pistaciae. Some info on the gall: http://knol.google.com/k/jean-jacqu...a-pistaciae-l-a-gall-inducer/2lu56ivsd9r6u/3# edit: typo