I think you can plant rhubarb later in the season so long as it gets established before it gets cold in the winter. You might have to water it more in the summer though.
That looks like a picture of Swiss chard, you can eat the leaves and stem if it is.
Maybe this is again summer @lightsplasher i honestly say i have never seen that plant i will share this post let me many friends who are in steemit know about this plant @lightsplasher
Thank you so much for your friend @lightsplasher who has given me a very meaningful suggestion for me to be a science in the process of planting this rhubarb if I will plant in summer. Maybe you like my post this friend @lightsplasher. https://steemit.com/photography/@burhanuddin/the-most-beautiful-unique-insect-c458d6067e7ca