列当属（学名：Orobanche）是列当科草本的寄生植物，约有200多种，主要分布于北半球温带地区。

属于小型植株，约10厘米至60厘米高。完全不具叶绿素，而呈白色至深褐色，花为白色或蓝色唇形的花。虽然单花列当 (O. uniflora)的花为单生，大部份的种类由大约10至20朵花构成穗状花序。

列当的叶通当仅呈鳞片状、三角形。种子极小，黄褐色至褐色，随年纪而变深。通常于晚冬至隔年春末开花，植株未开花时常常在地表下不可见。

由于本属植物不具叶绿素，它们需借由其他植物获取营养。其种子在土壤中呈现休眠状态，其萌发常常是受到其宿主的根部所分泌的物质所引发 。其幼苗的形态类似根状，会吸附到附近的宿主根部，一旦吸附到其宿主上，便由宿主吸取水份及养份。

Orobanche (broomrape or broom-rape) is a genus of over 200 species of parasitic herbaceous plants in the family Orobanchaceae, mostly native to the temperate Northern Hemisphere. Some species formerly included in this genus are now referred to the genus Conopholis. The broomrape plant is small, from 10–60 cm tall depending on species. It is best recognized by its yellow- to straw-coloured stems completely lacking chlorophyll, bearing yellow, white, or blue snapdragon-like flowers. The flower shoots are scaly, with a dense terminal spike of between ten and twenty flowers in most species, although single in O. uniflora. The leaves are merely triangular scales. The seeds are minute, tan-to-brown, and blacken with age. These plants generally flower from late winter to late spring. When they are not flowering, no part of the plants is visible above the surface of the soil.