By Amy Sahud

Apr 13 2023

Upon first glance, this mounted specimen may seem nothing more than an unassuming woody shrub. But look closer and you will find another wonderful flowering body lurking beneath (and sprouting from) the surface. Zoom in on the woody stems to discover a small cluster of red flowers—these belong a parasitic plant bearing the scientific name Pilostyles haussknechtii.

Aptly nicknamed “stemsuckers,” plants in the genus Pilostyles are endoparasites that live inside of their hosts. Against all expectations one may have of a plant, these parasites have no stems, leaves, or roots. And with no chlorophyll, these plants can’t photosynthesize; they rely solely on the host plant for sugar, water, and other nutrients. Before flowering from the host plant’s stem, Pilostyles lives within the stem tissue as a system of connected cells, much like fungal mycelium. The entirety of the floral development occurs within the stem tissue and once developed, clusters of flowers burst from the tissue and bloom.

Pilostyles was once believed to belong to the family Rafflesiaceae, a family of parasitic plants that is the home of infamously large, rot-smelling flowers. Thanks to Filipowicz and Renner’s phylogenetic analyses through gene sequencing in 2010, these plants were determined to be in an entirely different order, meaning they are more closely related to begonias and squash than to those smelly parasitic plants.

We may often think of parasites as bacterial or fungal, but let it be known that flowers, too, can grow within other plants. Species like Pilostyles haussknechtii are an amazing window into the diversity, strangeness, and wonder of the plant world.

A Closer Look

More about: Seed plants

Herbarium specimens examined for this research were digitized as part of the “All Asia” Digitization Thematic Collections Network, funded by the US National Science Foundation (award # 2100755).