Smoke bush (smoke tree, Cotinus coggygria, Anacardiaceae) is in the sumac family. It is called “smoky bush” because the long stalk-like structure supporting the seeds (most stalks are empty with a few seeds here and there), in yellow or pick color, gives a smoke like appearance when viewed afar.
I have seen bees visiting this plant in front another botanic garden but then I saw a large patch of it near the MSU bee biology building. Last year it was blooming June 2 and I took some photos with my cell phone and next day I went back and took more with my D700. This year they are blooming again now. Honey bees seem to love this plant. I assume it provides both nectar and pollen. Bees do not stay very long (1-2 seconds) per flower so I did not have super close photos (unlike the autumn olive ones, bees stay for longer than 3 seconds, so it was quite easy to get them).
This tree turns colors in the fall, yielding yellow or red leaves. Hence the Chinese name for it is 黄栌 (yellow haze).
1. Flowers only
2. A honey bee in flight.
3. This bee landed
4. Now we can see the pollen on the pollen baskets clearly.
5. A honey bee hanging upside down, clearly probing for nectar.
6. A very small bee, perhaps a halictid?
7. A damsel fly also on the flowers. Therefore, anytime you plant good nectar plants for honey bees, you will be also helping other insects, who also exploit flowers for pollen (many solitary bees) and nectar (e.g. damselflies or butterflies).