Garden rhubarb and Rhubarb plant

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

Rhubarb plant and garden rhubarb are semantically related. In some cases you can use "Rhubarb plant" instead a noun phrase "Garden rhubarb".

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.

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