A single fungal hypha enters through a long side of a plant cell and grows by iterated dichotomous branching until every tip meets the cell wall.
Trypan blue: classic bright-field stain, blue hyphae on a cleared white background. Fluorescein: fluorescence-microscopy look, glowing green hyphae with a DAPI-blue nucleus on black.
Each branch point picks an angle between the two sliders above. "Random" picks it uniformly at random. "Adapt to available space" tests several angles in that range and keeps the one giving both daughter branches the most clearance before hitting the wall or the nucleus.
Each new segment's length is its parent's length reduced by this percentage, so branches get shorter (as well as thinner) deeper into the tree.
Each segment tapers smoothly along its own length from the diameter it inherited from its parent down to this reduced diameter — no abrupt step at the branch point.
AM fungi rely on lipids/carbon supplied by the plant to build the arbuscule. Growth consumes carbon in proportion to the volume of hyphal tissue produced, and stops spawning new branches once this budget is used up — even if there's still open space in the cell.
Sets where on the long side wall the trunk hypha enters, as a % of the space available on that face (0% = center). The trunk's initial angle relative to the wall is randomized by the seed each time (up to 60° of tilt) but is never allowed to lie flat/parallel to the wall.
Sets where the nucleus starts, as a % of the space available on each axis (0% = center). Once growth starts, the nucleus is pushed out of the way as hyphae fill the space around it.
Checked (default): a growing hypha shoves the nucleus completely clear of its path and keeps growing to its full length — it only stops short if the nucleus truly has nowhere left to go (e.g. pinned against the wall or other hyphae). Unchecked: hyphae instead just route around wherever the nucleus currently happens to be, giving it only a gentle nudge as a side effect.
Cell modeled as a rounded shoebox; length, height and depth are all adjustable above. The trunk hypha starts exactly at the cell wall surface (the length × height face) at a position set by the entry-point sliders, and every growing/terminal hyphal tip has a rounded cap rather than a flat-cut end. Trunk diameter and tip diameter (~5–10 µm → <1 µm) follow reported arbuscule morphology. Each branch's 3D orientation is randomized independently, so the tree fills the cell volume rather than a single plane. Growth of a branch stops when it would cross the cell wall or the nucleus, fall below a minimum diameter, or exhaust the plant's carbon budget. Hyphae are rendered slightly transparent with a dark outline so overlapping branches and the nucleus stay readable.