xruba -xub- gismu

x1 is a quantity of buckwheat/rhubarb/sorrel grass of species/strain x2.

See also spati.

In notes:

spati
x1 is a plant/herb/greenery of species/strain/cultivar x2.
pezyxruba
x1 is a quantity of sorrel of subspecies x2.
stanyxruba
x1 is a quantity of rhubarb of species/strain x2.