(This Character was based on the story Cadmus Seed (Alarming Tales #1 September 1957 by Jack Kirby; available at Comic Book Plus here). I made a few changes since a few infantry divisions of these guys is a real game changer.)
They used a rare seed found in the Congo. It was nurtured with cuttings from the U.K.s Green Man and mysterious serums from the West Foundation and other more troubling materials. In the end they had a mobile plant that resembled humans and had limited intelligence. The project was more ambitious when it started. The Allies wanted divisions of the creatures. But they had few successes and the West Foundation was eventually deemed too risky to use further. In the end they had a single success and another half dozen near misses that they might train up. Ironically they called their best subject Cadmus.
The Cadmus Men
Cadmus and his brothers barely notice bullets (have you ever tried to shoot a tree?) A bullet one point of damage to them. therefore being caught in suppressive fire would do 0-3 points. Cadmus is -/+ AC due to his thick bark-like skin..
Cadmus' hands are the density of oak wood letting him do 1d6 damage in hand to hand combat.
In daylight Cadmus heals 1d6 damage per day and does not need to remain at rest. Cadmus requires half as much food as a normal human. These benefits vanish if Cadmus must spend his time indoors, underground or out of direct sunlight.
Defoliants and Fire
Weed killer and similar chemicals do 1 or 2d6 to Cadmus. Fire does normal damage and Cadmus must make an ST to fave a flamethrower or similar weapon.
Cadmus and his brothers are not verbal or deep thinkers. To make more than a monosyllabic reply requires an ST. Using a complex weapon or device (like a machine gun) in combat may require a saving throw (though rifles and pistols are fine until they need a reload.
Cadmus and his brothers use the XP, hit dice, BHB and ST of Grunts.