Broomrape

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Broomrape or Broom-rape (Orobanche) is a genus of about 150 species of parasitic herbaceous plants in the family Orobanchaceae, mostly native to the temperate Northern Hemisphere^[1]. 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 10-20 flowers in most species, though 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 these plants is visible above the surface of the soil.

As they have no chlorophyll, they are totally dependent on other plants for nutrients. Broomrape seeds remain dormant in the soil, often for many years, until stimulated to germinate by certain compounds produced by living plant roots ^[2]. Broomrape seedlings put out a root-like growth, which attaches to the roots of nearby hosts. Once attached to a host, the broomrape robs its host of water and nutrients.

Some species are only able to parasitise a single plant species, such as Ivy Broomrape Orobanche hederae, which is restricted to parasitising ivy; these species are often named after the plant they parasitise. Others can infect several genera, such as the Lesser Broomrape O. minor, on Trifolium and other related Fabaceae.

Branched broomrape Orobanche ramosa, native to central and southwestern Europe but widely naturalised elsewhere, is considered a major threat to crops in some areas. Plants that are parasitized are tomato, eggplant, potato, cabbage, coleus, bell pepper, sunflower, celery, and beans. In heavily infested areas, branched broomrape can cause total crop failure.

Species (not a complete list)

• Orobanche aegyptiaca Egyptian Broomrape
• Orobanche alba Thyme Broomrape
• Orobanche alsatica Alsace Broomrape
• Orobanche amethystea Eryngium Broomrape
• Orobanche arenaria Wormwood Broomrape
• Orobanche cernua Nodding Broomrape
• Orobanche caryophyllacea Bedstraw Broomrape
• Orobanche elatior Knapweed Broomrape
• Orobanche fasciculata Fascicled Broomrape
• Orobanche gracilis Slender Broomrape
• Orobanche grayana Gray's Broomrape
• Orobanche hederae Ivy Broomrape
• Orobanche loricata Oxtongue Broomrape
• Orobanche ludoviciana Desert Broomrape
• Orobanche lutea Medick Broomrape
• Orobanche maritima Carrot Broomrape
• Orobanche minor Lesser Broomrape
• Orobanche purpurea Yarrow Broomrape
• Orobanche ramosa Branched Broomrape
• Orobanche rapum-genistae Greater Broomrape
• Orobanche reticulata Thistle Broomrape
• Orobanche teucrii Germander Broomrape
• Orobanche uniflora Naked Broomrape

See also

• Parasitic plant

References