The trees you see here are akeake, dodonaea-viscosa. Slender, slightly stiff leaves on a trunk that looks a lot like kanuka/manuka. The flowers are pale green/yellow and their seed cases have wings. There is also a red leafed variety that is popular in garden shops.
Just a few decades ago Kaipupu Point was farm land. Now there are a wide variety of native trees on this Sanctuary. As well as akeake and kanuka; tawhai (beech), kamahi, whauwhaupaku (five finger), mingimingi, māhoe and kawakawa are just a few I readily recognised that come to mind easily.
By the way...
How to tell manuka from kanuka: Manuka has prickly leaves (you might be able to guess my mnemonic, but I can't repeat it here, there are children present). Kanuka leaves are soft. Manuka seed cases stay on the tree all year, old seed cases are the same colour as the bark. Kanuka drop their seed cases, so you don't see old seed cases on kanuka. Aside from that, both plants look identical.
Supporting the GeoKids program - my caches have treasure, makes them fun for kids to find!