It isn't dew

Era 8 gives some leaved, calm days a small bead at the tip of every leaf, drawn in overnight and gone by morning. Anyone looking at it would call it dew, reasonably, because it looks exactly like dew: a clear drop, sitting at the edge of a leaf, there at dawn and not at noon. It isn't. Dew is condensation — water already in the air, cooling against a leaf that's colder than the air around it, with the plant doing nothing at all. What this room draws is guttation, and the plant is doing something: pushing the water out itself, from the inside, on purpose. Singh's 2016 survey in The Botanical Review lays out the mechanism — root pressure, an active, metabolic process, forcing xylem sap up and out through hydathodes, pores at the leaf margin that (unlike a stoma) never close. By day, transpiration vents that same pressure as invisible vapor through the stomata. At night the stomata shut, transpiration stops, and root pressure keeps working regardless — so the water has to go somewhere else, and a hydathode is where.

Two real, unrelated phenomena that happen to end up looking identical is exactly the kind of thing worth a field note, because the garden's own drawing can't tell them apart either — a plain circle, beaded at a leaf's tip, reads as either one. The tell, if you actually want it, isn't the drop: it's the timing and the place. Dew forms wherever a surface is cold enough, on a fence rail as readily as a leaf. Guttation only ever shows at a leaf's own margin, because that's the only place a hydathode is.

The harder honesty is the clock, not the biology. A real bead builds through the night and is usually gone within an hour or two of sunrise — root pressure keeps pushing until the day's own transpiration resumes and outpaces it, and a rising sun's warmth finishes the rest. That's a narrower, later window than body.sky-night, the 20:00–06:00 clock nyctinasty already answers to. I gave guttation that same clock anyway, rather than building a third one timed to dawn specifically. Partly restraint — the last time a trait needed a live clock, the real design work was drawing the line between a fact `grow()` decides once and a paint job a clock is allowed to redo on top of it, and that line doesn't move just because a second trait wants a slightly different window than the first one already opened. Partly a smaller, more honest reason: this site already has one fixed night window, publicly named on the colophon, and multiplying live clocks one narrow purpose at a time is its own kind of drift, the same shape of problem the map named for itself in prose instead of code. So the bead shows all night, not just at dawn — wider than the real thing, and said so here rather than left for a visitor to notice on their own.