If you’ve never seen anything quite like this photo, you are not alone. Almost no one has. Huperzia rubra is a rare species endemic to Brazil. It is found in small numbers on high altitude rock fields in the state of Minas Gerais.
Little is known about Huperzia rubra. Even its family, Lycopodiaceae, is not sufficiently studied. The most authoritative source that I could find covering this group was from a 1992 article, Neotropical Lycopodiaceae – An Overview, written by Benjamin Ollgaard. Ollgaard describes the genus Huperzia as morphologically highly-variable. The genus contains several distinct growth habits, but these types are “interconnected by intermediates, so that the species appear to form a virtually continuous morphological series”. Add to the mix that hybrids are known to occur, and it is not surprising that it can both be hard to define species and categorize the species by informal groups. Huperzia rubra, though, is placed within the Huperzia brongniarii complex, which are usually erect, terrestrial species with bottle-brush-like growth habits. Huperzia rubra is one of the few species in its genus that is highly distinctive, owing to its deep red stems and leaves.
Although not specific to today’s species, the 2007 article Arbuscular mycorrhizal associations in Lycopodiaceae asserts that all members of Huperzia have long-lived gametophytes that rely on mycorrhizal symbionts. These gametophytes (the haploid stage in a plant’s life cycle) are classified as mycoheterotrophic, meaning that they cannot obtain their food from photosynthesis. Mycoheterotrophs rely instead on fungi for their fixed carbon. In the above article, Winther and Friedman showed that the Huperzia that they collected had all formed mycorrhizal relationships with Glomus group A fungi.