Ask the Expert: need the name of plant/patio type nurseryman in southeast Texas called this plant a cup plant but I don't believe this is correct. Plant height is around 16" mature, has a woody, branching habit, and bears white or yellow flowers resembling a small 1 1/2 inch primrose or potentilla flower. the leaves are dark green and are very similar to a penta. I was told it will propagate via harvested seed. Donna Reply: I think you are probably right it doesn't sound like cup plant (Silphium perfoliatum) which is shown to the right. I found a picture of cup plant on the Connecticut Botanical Society website. and its minimum height is 4ft. It could be a form of Nierembergia which is sometimes called cup flower. However, the white flowering ones don't grow that tall. Do you have a picture of the plant? I could probably make an identification from the picture. Share this:Click to print (Opens in new window)Click to email a link to a friend (Opens in [...]