Husk

Something like this pushes up through leaf litter in the forests of East and Southeast Asia, and at a glance it could pass for a mushroom: a squat, cap-shaped head, no leaves, no green anywhere, no stem worth calling a stem. It has been mistaken for a fungus often enough that its own family's classification stayed muddled for a long time. It isn't one. Balanophora is a flowering plant — the genus name is Greek for “acorn-bearing,” after the shape of its flower cluster — that gave up photosynthesis entirely and steals everything it needs from a nearby tree's roots instead.

Above ground the two look close enough to fool a glance. Below ground they share nothing. A mushroom's cap sits on mycelium — fine threads that are the fungus's own body, spreading through the soil to feed itself, whether or not any tree is nearby. Balanophora has no such network of its own: what's under its cap is a tuber, fused directly onto a living root of its host tree, drawing water and nutrients the tree already made. It keeps no chlorophyll and no conventional root system at all — the whole plant is, structurally, a graft that flowers.

Neither of those two undergrounds is the usual way a fungus meets a root, though, and the toggle above said nothing about that until now — press it a second time and the left side swaps its free mycelium for a mycorrhizal fungus instead. Most fungi that do touch a living root don't fuse onto it the way Balanophora fuses onto its host; they trade with it. A mycorrhizal fungus wraps fine hyphae around a root, or, in the arbuscular kind drawn here, grows briefly inside the root's own cells, swapping phosphorus and other minerals the fungus is better at finding for sugar the plant makes by photosynthesis — both directions, ongoing, nobody fused to anybody. It's the majority arrangement among land plants, not a curiosity: a 2018 review counted roughly 72% of vascular plant species hosting the arbuscular kind alone, with several other mycorrhizal types covering still more ground. Balanophora's tuber, next to that, is close to a real fungus's opposite — permanent, one-directional, and not a fungus at all.

A phylogenomic study published in New Phytologist in November 2025 (Svetlikova, Su, Suetsugu & Husnik) sequenced seven Balanophora species across twelve populations in Taiwan and Japan and found that a shared ancestor abandoned photosynthesis roughly 100 million years ago, in the mid-Cretaceous — and that its plastid genome, the small stretch of DNA a plant keeps inside its chloroplasts, collapsed from something on the order of 200 genes down to about 20. The plastid itself didn't disappear. It just stopped doing photosynthesis and kept a handful of other jobs instead, which is part of why the study calls this “metabolic retention in reduced plastids” rather than plastid loss.

The same study found something stranger in how these plants make more of themselves. Most flowering plants need pollen to set seed; some island populations of Balanophora have given that up too, cloning themselves instead of ever being fertilized — never mixing genes with another plant, generation after generation. Losing sex outright looks like it happens more easily on islands, where a single seed that never needs to find a mate to start a new population has an obvious edge over one that does.

Honest gap: this room draws one generic Balanophora plant, not any single one of the seven species the study actually sequenced — the underground anatomy above is a simplified schematic, not measured from a real specimen, and no species is named here on purpose. Its own mycorrhizal drawing is narrower still: it shows one arbuscular fungus wrapping one root, not the several distinct mycorrhizal types (ecto-, ericoid, orchid) the 2018 review below actually counts, and the fungus's own species is invented rather than a stand-in for any real one, on purpose, same as the room's other underground drawing. The specific facts in the paragraphs above (no chlorophyll, a tuber fused to a host root, roughly 100 million years, roughly 200 genes down to about 20, some island populations reproducing only asexually, the ~72% arbuscular figure) are the cited studies' and Wikipedia's own claims, not this room's invention.

Sources: OIST's own writeup of Svetlikova, Su, Suetsugu & Husnik, “Phylogenomics clarifies Balanophora evolution, metabolic retention in reduced plastids, and the origins of obligate agamospermy,” New Phytologist, 2025 (paper); general biology, the fused-tuber attachment, and the genus name from Wikipedia's Balanophoraceae article; the mycorrhizal figures from Brundrett & Tedersoo, “Evolutionary history of mycorrhizal symbioses and global host plant diversity,” New Phytologist, 2018 (paper).