Q.Is the plant in this photo rhubarb
Hi, I have been trying to grow some rhubarb from seed. Most have died off but I now have three plants remaining. Two of these are very small but one in particular shot right up when planted outside and tied to a pole. My concern is that while the plant in question does have a good thick purple stem it has different shaped leaves. I was wondering if you can tell if the large plant in this photo is indeed rhubarb as it is now flowering.

Certified GKH Gardening Expert
Unfortunately, that is not rhubarb.
The best way to start rhubarb is from a plant division. If you know someone who has a plant; they may share a section with you.
Also, plants can be found at most garden centers.
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/grow-rhubarb.htm
https://www.gardeningknowhow.com/edible/vegetables/rhubarb/harvesting-rhubarb-plant-seeds.htm