holoparasiittinen

Holoparasiittinen refers to a type of parasitic plant that obtains all of its necessary nutrients and water from a host plant. Unlike hemiparasitic plants, which can photosynthesize to some extent, holoparasitic plants lack chlorophyll and are unable to produce their own food. They possess specialized structures called haustoria, which are modified roots that penetrate the host's tissues, typically the xylem and phloem. Through these haustoria, the holoparasite absorbs water, minerals, and sugars directly from the host.

These plants are often characterized by their lack of green coloration, appearing instead in shades of yellow, brown, or red due to the absence of chlorophyll. Their morphology is frequently simplified, with reduced leaves or even the complete absence of them, as they do not need them for photosynthesis. Examples of holoparasitic plants include dodders (Cuscuta spp.), broomrapes (Orobanche spp.), and Rafflesia arnoldii, famous for its enormous flower.

The relationship between a holoparasite and its host is entirely exploitative. The host plant is significantly weakened by the drain of resources, often leading to reduced growth, stunted development, and increased susceptibility to diseases and environmental stress. In severe cases, the host plant can be killed. The life cycle of holoparasites often involves seeds that remain dormant in the soil until they detect the chemical signals from a suitable host. Upon germination, a seedling rapidly grows a searching hypha that seeks out a host to attach to with its haustoria.