Today’s photo features the yellow morph of Kopsiopsis strobilacea. This Pacific Northwest species is a member of the Orobanchaceae, or broomrape family.
Botany Photo of the Day has recently covered another parasite, the mycoheterotrophic Allotropa virgata. Like Allotropa virgata, the non-photosynthetic Kopsiopsis strobilacea relies on a host for its survival. Allotropa virgata, however, obtains its food from a fungus, whereas today’s species taps directly into flowering plants for its meal. Kopsiopsis strobilacea is termed a holoparasite (it cannot complete its life cycle without a host). It is also known as a root parasite, as it connects to the roots of its host. Kopsiopsis strobilacea parasitizes madrone trees (Arbutus spp.) and manzanita shrubs (Arctostaphylos spp.).
The common name for Kopsiopsis strobilacea is California ground-cone. Today’s photo of the yellow morph of the species provides a hint of its resemblance to a cone from a coniferous tree. The more common form of Kopsiopsis strobilacea is dark purple to brown, and looks even more like a conifer seed cone. A photo of a more typical California groundcone was featured on BPotD in 2008, and it gives a good indication of how well this species might blend into the Pacific Northwest forest floor. No matter how cone-like Kopsiopsis strobilacea looks, its flowers reveal that it is a member of the Angiosperms (the flowering plants). The four-lobed flowers stick out from the scale-like bracts in the spring.
The 2008 entry shows another key aspect of this species: its root-like haustorium. Unlike most flowering plants, Kopsiopsis strobilacea lacks roots. Instead, it has a haustorium, whose purpose it is to penetrate the roots of its host and to withdraw water and nutrients. In the book, Parasitic Orobanchaceae, Joel, Gressel, and Musselman explain that holoparasitic Orobanchaceae are able to germinate independently of a host. As seedlings mature, the haustorium develops at the tip of the radicle (the embryonic root). Next, the seedling develops an attachment organ–in most Orobanchaceae this consists of specialized root hairs (haustorial hairs) arranged around the penetration site. The haustorial hairs are covered by a glue-like secretion that cements the hairs to the host. During this time, intrusive cells form. Once the the attachment organ has completed its task, these cells penetrate the host root. Although some parasites penetrate their host by dissolving the host’s cell walls, Joel et. al. assert that this is not the case in Orobanchaceae. Kopsiopsis strobilacea enters its host by mechanically pushing its way between the host’s cells, aided by enzymes that degrade the host’s cell wall.