Blood-drop-emlets

E. lutea blooms in the summer and grows to about 30 centimetres (12 in) in height. The flowers are yellow with irregular red blotches and the leaves are hairy, paired, and round. Because of its yellow petals, E. luteus is in the "yellow monkeyflower" group, unlike most members of the genus, which have red or pink petals. Some sources list Erythranthe lutea separately due to chromosomal variations. Barker, etal (2012) proposes a new taxonomy for Phrymaceae, leaving only 7 species in Mimulus, none in Mimulus lutea, and placing 111 in Erythranthe. Barker also offers 4 different options for how to implement this new taxonomy. The luteus group consists of Erythranthe luteus var. variegatus, E. naiandinus and E. cupreus.

Erythranthe lutea prefers to grow in wet habitats such as marshes and riverbanks. It is native to temperate South America, including Chile and western and southern Argentina. It has been naturalized in Britain, having been first cultivated there circa 1826.