Painting new pathways: Castilleja enters the genomic era

Castilleja (Orobanchaceae), commonly known as Indian paintbrush, is a genus of approximately 200 hemiparasitic species found primarily across the Americas. Long studied for its taxonomic complexity, vibrant floral displays, and ecological interactions with host plants, Castilleja has recently emerged as a versatile research system spanning parasitic biology, specialized metabolism, conservation genetics, and pharmacology. The availability of whole-genome sequencing is transforming the field, revealing expanded gene families involved in host recognition, enabling genomic species delimitation of cryptic taxa, and providing frameworks for mapping biosynthetic pathways of bioactive compounds, including iridoid glycosides and phenylethanoid glycosides. This review synthesizes advances across these disciplines and highlights how genomics serves as an integrative force connecting taxonomy, ecology, phytochemistry, and parasitic biology in this genus.