Hippuris vulgaris
An aquatic buffer that pools armour from its benched ruderals and pins its target, wilting the enemy active once mature — a widespread native with no invasive form.
Common mare's tail is a slim Aquatic that fights as a bench-fed buffer, drawing armour from the ruderals behind it while pinning down what it hits. It is native across East Asia, Europe, North America, South America and South Asia, where it plays a native buffer; no invasive form of this species exists, so it is only ever a defensive piece. Its attack is fair, and its very slow opening means it fights best over the long haul.
Its starter attack, Davy Jones, unlocks at level 1 for 2 Sun, dealing about 36 damage. The free once-per-battle ability, Eutrophic Pulse, arrives at level 25: A nutrient bloom fouls the water — the foe's whole bench sickens. The advanced attack, Floodmat, unlocks at level 40 for 6 Sun (43 damage) and pins the target in place as it strikes. Most of your mare's tail sit below level 40, where only the starter is unlocked. None of its moves carry an initiative rider. See Moves.
Common mare's tail keeps two always-on traits. Duff Stuff arrives on the level 10 riser: while it is your active its effective DEF rises by half the combined DEF of your still-standing benched ruderals — annual forbs, grasses, aquatics and bulbs — recomputed every turn, so the cushion shrinks as those allies faint, and the donors keep their own armour. It is a real, always-on defence, not a chance effect. Allelopathy arrives on the level 68 riser: it projects a wilt aura onto the enemy active, sapping the card it faces. See Abilities.
Common mare's tail is non-toxic: it holds no Toxin trait, so striking it costs an attacker nothing in contact recoil and it lays no poison. Its growth habit is terrestrial, so it is not eligible for a Moss Pole. As a native, defensive field gear — a Cloche, or a calcium or magnesium amendment for a little DEF — helps offset its thin armour. See statuses.
At level 40 common mare's tail reads 103 HP with ATK of 29, among the higher figures for a ruderal here. DEF is just 1, at the soft floor of the aquatic band, so it takes hits with almost no armour of its own and depends on the pooled Duff Stuff bonus instead. Its tempo is badly lopsided: turn 1 runs on a very low initiative (22) and every turn after on a high SPD (53), so it is badly out-paced off the mark but among the fastest cruisers here once a fight settles in. Retreat costs 11 Sun. As a native it gains a +15% HP cushion and, while benched, projects an HP overshield onto your active. See Stats.
Matured to level 100, common mare's tail swells to 190 HP and 54 ATK, but its DEF only reaches 1 — as a soft aquatic it buys bulk in health and almost none in armour, so it stays exposed to any real hitter and still leans on its bench for defence. Retreat rises to 21 Sun, and its tempo has sunk to about 1% of cap, so a mature mare's tail acts last against almost anything younger.
As an aquatic, common mare's tail sits in the Ruderal succession group. It hits Specialist plants — succulents, conifers, ferns and epiphytes — for ×1.5 while taking only ×0.667 from them; it is weak to Competitor plants — perennial herbs, shrubs and trees — which strike it for ×1.5 and shrug off its blows. Against other Ruderals and the off-wheel Weird group the matchup is neutral. See Weaknesses & Resistances.
Play common mare's tail as a native buffer built for the long fight: keep a bench of other ruderals behind it so Duff Stuff can prop up its armour, accept that it acts near-last on turn 1, and let its high cruising speed and pins wear a target down. Once mature, its wilt aura taxes whatever it faces. It is a fair support card, though its fragile armour caps how long it can hold. It is inedible, so any nutrient you feed it banks ×1.25 XP toward faster growth rather than coins. It plays as a very slow-opening but fast-cruising buffer that leans harder on its bulk as it levels, crossing over around level 25 — but it is always stronger at higher levels, so there is no reason to hold it back.
Leveling trades speed for power. A plant’s tempo (SPD + INI, the turn-order edge) fades as it grows, while its power (HP + ATK + DEF, net of the rising Sun cost to retreat) climbs. The crossover is the level where power overtakes tempo: below it the plant is a fast skirmisher, above it a heavyweight. Shown for each stance this plant can actually hold — native adds a HP cushion, invasive an attack edge, neutral neither — with the card at its crossover and fully grown at Lv 100.