Bamboo can grow while you watch it
The fastest bamboos put on close to a metre a day in the right conditions, which works out at a visible creep of about four centimetres an hour. They manage it by cheating: the cells are already made, stacked in the shoot, and the growth spurt is those cells filling with water and extending, rather than the plant building anything new.
The flowering is stranger still. Many BAMBOO species flower on a long clock — every few decades, and in some cases once every 120 years — and when they do, every plant of that species flowers at the same time, worldwide, including ones grown from cuttings on the other side of the planet. Then they set seed and die together. Botanists still cannot fully explain how the timing is kept.
That single habit has consequences for people. In parts of north-east India, the mass flowering of one bamboo produces a glut of seed, the rat population explodes on it, and when the seed runs out the rats move into the rice. Famines there have been predicted decades ahead by counting back to the last flowering.
Two of these are not plants at all
A LICHEN is not one organism. It is a fungus and an alga living inside one another so completely that the result has its own name, its own shape and its own habits — the fungus builds the structure and collects water, the alga makes the food. When this was proposed in the 1860s it was rejected as nonsense, and it turned out to be the discovery of one of the most common arrangements in nature.
SEAWEED is not a plant either, whatever it looks like draped over a rock. It has no ROOT, no STEM and no LEAF — the part gripping the rock is a holdfast that does no drinking at all, because the whole surface absorbs what it needs from the water around it. A MUSHROOM, meanwhile, is a fungus and closer to an animal than to a FERN, which tends to unsettle people who have just eaten one.
MOSS sits in a third category: a real plant, but one that never developed plumbing. With no tubes to move water upwards it cannot grow tall or live anywhere dry for long — which is the entire reason moss is always low, always in the damp corners, and always spreading rather than rising.
Everything in the grid, including the ones that fight back
The survivors first: the CACTUS, whose spines are its leaves and whose fat STEM does the photosynthesis; the SUCCULENT storing water in swollen foliage; LICHEN and MOSS on bare rock; FERN and BRACKEN unrolling in the shade. Then the climbers and spreaders — IVY, the VINE, BAMBOO — and the open-ground crowd: CLOVER, THISTLE, HEATHER, REED and SEAWEED, with a SHRUB and a kitchen HERB for the tidier end of the plot.
The NETTLE deserves its reputation. Its sting is mechanical as well as chemical: each hair is a brittle tube of silica with a sealed tip that snaps off on contact, leaving a needle sharp enough to enter skin, through which the irritants are delivered. Heat wrecks the whole apparatus, so nettle soup is harmless and nettle-grabbing is not.
The rest of the list is the machinery every plant is built from — the ROOT, the STEM, the LEAF, a BULB holding next spring's supplies underground, and a SEEDLING or SPROUT with all of it still ahead.