Ponderosa lemon
The ponderosa lemon originated in roughly 1887, and is believed to come from a chance seedling grown in Hagerstown, Maryland. It was later named and introduced to the nursery trade in 1900. Though often referred to as a cross between the lemon and citron, a recent genomic analysis showed it to solely contain pomelo ("Citrus maxima") and citron ("Citrus medica") DNA, perhaps being an F2 hybrid. Thus they cannot derive from true lemons, which have a mandarin orange component.
Chrysopogon zizanioides
Vetiver is most closely related to "Sorghum" but shares many morphological characteristics with other fragrant grasses, such as lemongrass ("Cymbopogon citratus"), citronella ("Cymbopogon nardus", "C. winterianus"), and palmarosa ("Cymbopogon martinii").