Pie plant and Rhubarb plant

Pie plant noun - Long cultivated hybrid of Rheum palmatum; stems often cooked in pies or as sauce or preserves.

Rhubarb plant and pie plant are semantically related. In some cases you can use "Rhubarb plant" instead a noun phrase "Pie plant".

Rhubarb plant noun - Plants having long green or reddish acidic leafstalks growing in basal clumps; stems (and only the stems) are edible when cooked; leaves are poisonous.

Pie plant and rhubarb plant are semantically related. Sometimes you can replace phrase "Pie plant" with "Rhubarb plant", this phrases are similar.