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.
Genoplesium citriodorum
The lemon scented midge orchid was first formally described in 1991 by David Jones and Mark Clements who gave it the name "Genoplesium citriodorum" and published the description in "Australian Orchid Research". In 2002, Jones and Clements changed the name to "Corunastylis citriodora". The specific epithet ("citriodorum") is derived from the Latin words "citrea" meaning "the citron-tree" and "odor" meaning "smell", referring to the strongly lemon-scented flowers.