A plant without a body
In the vast savanna of the Brazilian Cerrado, a plant exists that has abandoned nearly every feature of plant life. Pilostyles blanchetii is an endoparasite, meaning it lives its entire life inside another organism. It has no roots, no stems, and no leaves. It does not photosynthesize and has no chlorophyll. For most of its life, its physical form is reduced to a network of cellular filaments resembling a fungal mycelium, weaving between the cells of its host plant. This vegetative body is made of strands of parenchyma cells that stay in close contact with the host's vascular system, from which it draws all water and nutrients.
Pilostyles blanchetii belongs to the family Apodanthaceae, a small group of about 10 species, all of which are extreme endoparasites. These plants are so specialized that they lack the shoot and root apical meristems that nearly all other plants use for growth. Instead, their cells form clusters and networks within the host's bark and cortex. Using advanced imaging techniques like micro-computed tomography, scientists have visualized this hidden network, showing how it forms extensive "islands" of parasitic tissue inside the host's branches. From these internal cell masses, specialized structures called sinkers, composed of modified vessel elements, connect directly to the host's xylem to extract resources.
The fleeting flower
The only time Pilostyles blanchetii becomes visible is when it reproduces. Tiny, reddish-brown flowers, measuring only 2 to 3 millimeters in diameter, erupt directly through the bark of the host plant. The flowers appear like small pimples on the stem before opening. They possess no true petals, only scale-like fleshy sepals. These flowers are unisexual, they are either male or female. Recent studies of P. blanchetii show that both male and female flowers can be linked by the same internal tissue network, the species may be monoecious, with a single plant producing both flower types.
The specific host plants for P. blanchetii in the Cerrado are legumes (family Fabaceae), particularly those of the genus Mimosa. The flowers develop completely inside the host tissue before they emerge, pushing their way through the periderm to the surface. Pollination remains something of a mystery, but small insects like beetles, ants, flies, and wasps are thought to be involved, attracted by nectar produced in the tiny flowers. After pollination, a female flower can produce over 100 seeds, each less than a millimeter long. The seeds themselves are remarkable, containing an embryo of just eight cells, the smallest known for any dicot plant. How these seeds disperse and find a new host remains unknown.