Rheum rhabarbarum and Rhubarb plant

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

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

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.

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